NU o .M6B,E RJ u 1l y, 2 0 0 8 5 ISSN: 1816-8957 Scientific Drilling ReportsononDeep Deep Earth Sampling and Reports Earth Sampling and Monitoring Monitoring Large Igneous Provinces and Environmental Impact 4 Sea-Level Changes and their Effects 19 Drilling from Antarctic Ice Shelf 29 First IODP Drilling with D/V Chikyu 38 Stress Estimates from Leak-Off Test 43 Riserless Mud Circulation 48 Impact Crater Mjølnir 55 Colorado Plateau Workshop 62 Published by the Integrated Ocean Drilling Program with the International Continental Scientific Drilling Program Editorial Preface Scientific Drilling ISSN Dear Reader: Scientiic drilling in Antarctica (p. 29) provided signiicant achievements within the International Polar Year (IPY). Coring from a loating ice shelf into the underlying seabed is—even with the assistance of penguins—not a trivial accomplishment. The data gained from this endeavor promise excellent records of past glaciations and sea-level changes that will complement ODP and IODP records from below the deep oceans. During her irst IODP drilling, the Japanese drillship Chikyu recently prepared for deep and riser-assisted drilling into the seismogenic zone offshore Japan (p. 38). In late 2008,, the totally remodeled and U.S.-sponsored .S.-sponsored S.-sponsored .-sponsored sponsored platform JOIDES Resolution will resume IODP operations following years of shipyard work. Her schedule (back page) includes another contribution to the IPY through drilling near Antarctica. ICDP will commence coring the unique archive of three million years of Arctic climate records from below the frozen Lake El´gygytgyn in northeastern Siberia. One poorly known effect of global warming is the response by the polar ice shields and related sea-level change. ANDRILL, IODP, and ICDP contributions to the IPY will help us better constrain the long-term effects of global warming on polar ice sheets and the effect on global sea level. Changes in sea level and its impact on sedimentary stratigraphy were extensively discussed at a joint academic– industry funded workshop (p. 19). Another report (p. 32) presents the irst continental European large-scale test bed for recycling of carbon dioxide into deep reservoirs in order to mitigate global warming. While mankind is largely considered the culprit of global warming, nature is responsible for the formation of Large Igneous Provinces (LIPs) that likely severely impacted the global environment in the geological past. A recent workshop (p. 4) addressed causes and effects of these enigmatic and geologically discrete events. Another meeting (p. 55) discussed the environmental effects of a large marine impact in the Barents Sea. Plans to core the Colorado Plateau in order to recover a continuous record of the early to mid-Mesozoic -Mesozoic Mesozoic Era not present within the ocean basins (plate tectonics stole it!) is presented on p. 62. A special issue of Scientific Drilling—Fault Zone Drilling—was published online in late 2007, providing a total of three issues of the journal in 2007. However, the he protracted drilling hiatus in IODP has temporarily reduced contributions of scientiic reports and caused a publication delay of this issue. Nevertheless, we hope our readers will appreciate the many diverse reports presented in this volume. A new development, an editorial board, is now providing peer-review of the major scientiic and technical articles in Scientific Drilling. In a inal note, wee regret to report that our managing editor Emanuel Soeding has departed IODP for new duties.. We wish him well and thank him for his help establishing Scientific Drilling. 1816-8957 (printed version) 1816-3459 (electronic version) Scientific Drilling is a semiannual journal published by the Integrated Ocean Drilling P rog ra m ( IODP ) w it h t he I nter nat iona l Cont inent a l S cient i f ic Dr il l i ng P rog ra m (ICDP). The editors welcome contributions on any aspect of scientiic drilling, including borehole instruments, obser vatories, and mon itor i ng ex per i ment s. T he jou r na l is produced and distributed by the Integrated Ocea n Dr il l i ng P rog ra m Ma nagement International (IODP-MI) for the IODP under the sponsorship of the U.S. National Science Fou ndat ion , t he M i n ist r y of E duc at ion , Culture, Spor ts, Science and Technolog y of Japan, and other participating countries. T h e j o u r n a l ’s c o n t e n t i s p a r t l y b a s e d upon research suppor ted under Contract OCE - 0 4 32224 f rom the Nat ional S cience Foundation. Electronic versions of this publication and in for mat ion for authors, ca n be found at ht t p://w w w.iodp.org/scient i f ic - dr illing/ and http://www.icdp-online.org/scientificdrilling/. Printed copies can be requested from the publication ofice. IODP is an international marine research drilling program dedicated to advancing scient i f ic underst a nding of t he Ea r t h by monitor i ng a nd sa mpl i ng subsea f l o o r e n v i r o n m e nt s . T h r o u g h m u l t i p l e drilling plat forms, IODP scientists explore the program’s pr incipal themes: the deep biosphere, environmental change, and solid earth cycles. ICDP is a multi-national program designed to promote and coordinate continental drilling projects with a variety of scientiic targets at drilling sites of global signiicance. Publication Ofice IODP-MI, CRIS Building-Room 05-101, Hokkaido University, N21W10 Kita-ku, Sapporo, 001-0021 Hokkaido, Japan. Tel: +81-11-738-1075 Fax: +81-11-738-3520 e-mail: journal@iodp-mi-sapporo.org url: www.iodp.org/scientiic-drilling/ Editorial Board Editor-in-Chief Hans Christian Larsen Editor Ulrich Harms Send comments to: journal@iodp-mi-sapporo.org Editorial Review Board Gilbert Camoin, Keir Becker, Hiroyuki Yamamoto, Naohiro Ohkouchi, Steve Hickman, Christian Koeberl, Julie Brigham-Grette, and Maarten DeWit Copy Editing Glen Hill, Obihiro, Japan. Layout, Production and Printing Mika Saido (IODP-MI), and SOHOKK AI, Co. Ltd., Sapporo, Japan. IODP-MI Washington, DC, U.S.A. Sapporo, Japan www.iodp.org Program Contact: Nancy Light nlight@iodp.org ICDP GeoForschungsZentrum Potsdam Potsdam, Germany www.icdp-online.org Program Contact: Ulrich Harms ulrich.harms@gfz-potsdam.de Hans Christian Larsen Editor-in-Chief Ulrich Harms Editor Front Cover: The ANDRILL drill rig in Southern McMurdo Sound, Antarctica. Mount Erebus, an active volcano is visible in the background right. Photo by Simon Nielsen. Left inset: Visitors (Emperor penguins) to the ANDRILL Program’s Southern McMurdo Sound Project site in late 2007. Photo by Cristina Millan. (See page 29)  Scientific Drilling, No. 6, July 2008 All igures and photographs courtesy of the IODP, unless otherwise speciied. Workshop Reports 4 Investigating Large Igneous Province Formation and Associated Paleoenvironmental Events: A White Paper for Scientific Drilling by Clive R. Neal, Millard F. Cofin, Nicholas T. Arndt, Robert A. Duncan, Olav Eldholm, Elisabetta Erba, Cinzia Farnetani, J. Godfrey Fitton, Stephanie P. Ingle, Nao Ohkouchi, Michael R. Rampino, Marc K. Reichow, Stephen Self, and Yoshiyuki Tatsumi 19 Drilling to Decipher Long-Term Sea-Level Changes and Effects — A Joint Consortium for Ocean Leadership, ICDP, IODP, DOSECC, and Chevron Workshop by Craig S. Fulthorpe, Kenneth G. Miller, André W. Droxler, Stephen P. Hesselbo, Gilbert F. Camoin, and Michelle A. Kominz Progress Reports 29 32 38 43 ANDRILL’s Success During the 4th International Polar Year The CO2SINK Boreholes for Geological Storage Testing The First D/V Chikyu IODP Operations: Successful Drilling and Coring During NanTroSEIZE Stage 1 Expeditions Estimation of Minimum Principal Stress from an Extended Leak-off Test Onboard the Chikyu Drilling Vessel and Suggestions for Future Test Procedures Workshop Reports 55 58 60 62 67 Technical Developments 48 52 Ultra-Deepwater Riserless Mud Circulation with Dual Gradient Drilling Magnetic Susceptibility as a Tool for Investigating Igneous Rocks—Experience from IODP Expedition 304 Marine Impacts and Environmental Consequences — Drilling of the Mjølnir Structure, the Barents Sea Drilling the North Anatolian Fault Scientiic Drilling of the Terrestrial Cretaceous Songliao Basin CPCP: Colorado Plateau Coring Project —100 Million Years of Early Mesozoic Climatic, Tectonic, and Biotic Evolution of an Epicontinental Basin Complex ICDP Workshop on Borehole Monitoring at the Nankai Subduction Zone: Building a Land-Ocean Borehole Network to Study the Seismogenic Zone News and Views 68 69 71 Upcoming Workshops News and Views Discussion Forum: Ocean Crust Drilling Schedules back cover IODP and ICDP Expedition Schedules Scientific Drilling, No. 6, July 2008  Workshop Reports Investigating Large Igneous Province Formation and Associated Paleoenvironmental Events: A White Paper for Scientific Drilling doi:10.04/iodp.sd.6.01.008 by Clive R. Neal, Millard F. Cofin, Nicholas T. Arndt, Robert A. Duncan, Olav Eldholm, Elisabetta Erba, Cinzia Farnetani, J. Godfrey Fitton, Stephanie P. Ingle, Nao Ohkouchi, Michael R. Rampino, Marc K. Reichow, Stephen Self, and Yoshiyuki Tatsumi Introduction 2006). To this end, a workshop on LIPs, sponsored by IODP Management International (IODP-MI) and the Consortium for Ocean Leadership, was held at the University of Ulster in Coleraine, Northern Ireland, U.K. .K. K.. on 22–25 July 2007 (Cofin et al., 2007). Earth’s history has been punctuated over at least the last 3.5 billion years by massive volcanism on a scale unknown in the recent geological past. Largely unknown mechanical and dynamic processes, with unclear relationships to sealoor spreading and subduction, generated voluminous, predominately maic magmas that were emplaced into the Earth’s arth’s lithosphere. The resultant large igneous provinces (LIPs� Cofin and Eldholm, 1994� Ernst and Buchan, 2001� Bryan and Ernst, 2008) were at times accompanied by catastrophic environmental changes. The interaction of the LIP-associated mantle processes with the Earth’s crust have produced a variety of surface expressions (Fig. 1a and 1b)� the most common present-day examples are oceanic plateaus (e.g., Kerguelen/Broken Ridge, Ontong Java, Manihiki, Hikurangi, Shatsky), ocean basin lood basalts (e.g., Caribbean, Nauru), magma-dominated divergent continental margins (e.g., the North Atlantic), and continental lood basalts (e.g., Columbia River, Deccan Traps, Siberian Traps). Environmental effects associated with LIP formation include climate changes, mass and other extinctions, variations in ocean and atmospheric chemistry, and Oceanic Anoxic Events (OAEs). Therefore, the geodynamic processes in the mantle that produce LIPs have potentially profoundly affected the Earth’s environment, particularly the biosphere and climate. The Integrated Ocean Drilling Program (IODP) affords unique opportunities to investigate LIPs and associated environmental effects, building upon results from the Ocean Drilling Program (ODP) and Deep Sea Drilling Project (DSDP) (Cofin et al., A multi-disciplinary group of eighty scientists representing academia, government, and industry from sixteen countries discussed strategies for advancing understanding of LIPs and associated environmental events using the three different IODP platforms and related technologies. During the workshop, which began with an examination of the United Nations Educational, Scientiic, and Cultural Organization (UNESCO) World Heritage “Giant’s Causeway” exposure of the North Atlantic LIP (Fig. 2), scientists investigating LIPs through ield, laboratory, and modeling approaches shared their expertise. Speciically, outstanding problems related to LIP origin, emplacement, and environmental impacts were discussed in plenary and breakout sessions. The workshop achieved the following:: • Identiied multidisciplinary, synergistic approaches to addressing outstanding Earth system problems associated with LIP science. Brought together scientists from widely different areas of expertise (e.g., petrology, paleontology, geodynamics, oceanography, geophysics, logging, volcanology, geochemistry, stratigraphy, tectonics, paleoceanography, paleomagnetics) to focus on how ocean drilling can address unresolved issues associated with the origin, • AA B ICELAND Solar Radiation 60° NORTH ATLANTIC SIBERIA EMPEROR HESS Climate Change Sea-Level Change COLUMBIA RIVER SHATSKY B Consequences of LIP Emplacement on the Earth System EMEISHAN CENTRAL ATLANTIC CO2 + SO2 Crustal Accretion 30° DECCAN Ocean Chemistry Change Deep Biosphere Impact Ocean Circulation Disruption Hydrologic Cycle Greenhouse Gas Release CH4 + CO2 Lithosphere PIGAFETTA YEMEN HAWAII EAST MARIANA 200 km CARIBBEAN ETHIOPIA MAGELLAN NAURU GALAPAGOS ONTONG JAVA CHAGOSLACCADIVEMALDIVE MASCARENE Superplume 0° Lithosphere Recycling NINETYEAST MANIHIKI WALVIS KAROO SOUTH ATLANTIC LOUISVILLE SOUTH ATLANTIC FERRAR MADAGASCAR -30° BROKEN Heat Transportation KERGUELEN HIKURANGI 270° 2900 km ETENDEKA PARANA 180° Hotspot-Ridge Interaction 0° Mantle Dynamics 90° -60° Core-Mantle Interaction ? Vigorously Convecting Outer Core Figure 1. [A] Phanerozoic global LIP distribution. Red = LIPs (or portions thereof) generated by a transient “plume head”; Blue = LIPs (or portions thereof) generated by a persistent “plume tail”. Taken from Coffin (2006). [B] A holistic representation of the process of LIP emplacement and associated environmental effects. 4 Scientific Drilling, No. 6, July 2008 • • • emplacement, and evolution of LIPs, as well as their impact on the environment. Exposed new scientists to the IODP and nurtured early career scientists, speciically with respect to how scientiic drilling can advance understanding of LIPs. Enhanced cooperation between the IODP and the International Continental Scientiic Drilling Program (ICDP). Explored partnerships among IODP, government, and industry. One of the major outcomes of the workshop was to deinee multiple pathways to enhance our knowledge of LIPs through scientiic drilling. These ranged from ancillary project letters, through individual expedition proposals, to a mission proposal. This white paper highlights the major problems associated with LIPs that can be addressed through scientiic drilling and related studies. It also highlights multidisciplinary approaches required to address such problems, as studies ies of LIPs encompass mantle geodynamics, emplacement processes, and environmental events affecting the lithosphere, hydrosphere, atmosphere, and biosphere. Past Achievements chievements Scientiic drilling has played a vital role in the exploration of LIPs, most importantly by providing the irst, and in many cases the only, ground truth from the igneous basement of submarine LIPs. While major advances in LIP research involve holistic observational, experimental, and modeling studies involving a broad array of Earth arth science expertise, results from scientiic drilling have been and will continue to be key components of interdisciplinary work. The irst dedicated igneous basement sampling investigations of submarine LIPs, conducted during the ODP, concentrated on three provinces:: the Ontong Java Plateau (Paciic Ocean), the Kerguelen Plateau/Broken Ridge (Indian Ocean), and the North Atlantic magma-dominated divergent continental margins (Fig. 1). Below, we e highlight the major results of these investigations, which have laid the groundwork for the next major phase of discovery during the IODP. Drilling results from ~120-Ma -Ma Ma Ontong Java Plateau basement rocks are complemented by studies of obducted plateau rocks exposed in the Solomon Islands (Andrews et al., 1975� Kroenke et al., 1991� Berger et al., 1993� Neal et al., 1997� Mahoney et al., 2001� Fitton et al., 2004a, b). All Ontong Java basement rocks recovered to date are remarkably homogeneous tholeiitic basalts with minor variations in elemental and isotopic composition, and they were deposited in a submarine environment. Partial batch melting (�30�) �30�)) generated the basalts (Fitton and Godard, 2004� Herzberg, 2004), with melting and fractional crystallization at depths of <6 km (Sano and Yamashita, 2004). The lavas and their overlying sediment indicate relatively minor uplift accompanying Figure 2. Giant’s Causeway (Ireland), part of the North Atlantic LIP. Note the stepped topography in the background, characteristic of flood basalt provinces. emplacement and relatively minor subsidence since emplacement. Primarily on the basis of drilling results, multiple models—plume (e.g., Fitton et al., 2004a), bolide impact (Ingle and Cofin, 2004), and upwelling eclogite (Korenaga, 2005)—have been proposed for the origin of the Ontong Java Plateau. Uppermost igneous basement of the Kerguelen Plateau/ Broken Ridge is dominantly tholeiitic basalt erupted above sea level (Barron et al., 1989, 1991� Schlich et al., 1989� Wise et al., 1992� Cofin et al., 2000� Frey et al., 2003), and it shows two apparent peaks in magmatism at 119–110 Ma and 105–95 Ma (Cofin et al., 2002). Geochemical differences among tholeiitic basalts erupted at each site are attributable to varying proportions of components from the primary mantle source (plume?), depleted mid-ocean ridge basalt (MORB)-related MORB)-related )-related -related asthenosphere, and continental lithosphere. Proterozoic-age zircon and monazite in clasts of garnet-biotite gneiss in a conglomerate intercalated with basalt at one drill site demonstrate the presence of fragments of continental crust in the Kerguelen Plateau, as inferred previously from geophysical (e.g., Operto and Charvis, 1995) and geochemical (e.g., Alibert, 1991) data. For the irst time from an intra-oceanic LIP, alkalic lavas, rhyolite, and pyroclastic deposits were sampled. Flora and fauna preserved in sediment overlying igneous basement provide a long-term record of the plateau’s subsidence, beginning with terrestrial and shallow marine deposition and continuing to deep water deposition. Seaward-dipping relector (SDR) wedges of the latest Paleocene-earliest Eocene North Atlantic LIP drilled off the British Isles during DSDP (Roberts et al., 1984), off Norway during ODP (Eldholm et al., 1987, 1989), and off SE Greenland during ODP (Duncan et al., 1996� Larsen et al., 1994, 1999) conirmed them to be thick series of subaerial lava lows covering large areas. Lavas on the landward side of the SDRs show geochemical and petrological evidence of contamination by continental crust, implying that they ascended through continental crust during early rifting, Scientific Drilling, No. 6, July 2008 5 Workshop Reports moving beyond the simplistic assumption of a compositionally homogeneous mantle, where density differences are only due to temperature differences, numerical simulations and luid dynamics laboratory experiments have found an astounding variety of plume sizes and shapes (Tackley, 1998� Davaille, 1999). Figure 3. Gravity map of the North Atlantic Ocean showing prominent V-shaped ridges in the basement topography around the Reykjanes Ridge south of Iceland. These represent crustal thickness variations of ~2 km. The yellow arrow shows the location of thick sediment drifts deposited by northern component water flowing southwards over the Iceland-Faeroes ridge. Thinner drifts are present south of the Greenland-Iceland ridge. whereas oceanward SDR lavas appear to have formed at a sealoor spreading center resembling Iceland. Drilling results from these margins indicate extreme magmatic productivity over a distance of at least 2000 km during continental rifting and breakup, with spatiotemporal inluence of the Iceland plume during rifting, breakup, and early sealoor spreading (Saunders et al., 1998). Mantle Geodynamics eodynamics In many respects, LIP magmatism remains quite enigmatic,, yet et its unique characteristics (e.g., volumes of erupted lava, time duration of volcanism, distinct geochemical composition with respect to MORBs, and frequency over geologic time) unequivocally highlight the importance of understanding the underlying physical, chemical, mechanical, and dynamic processes. The mantle plume model, in which dynamic instabilities of a thermal boundary layer (e.g., the D'' zone at the base of the Earth’s mantle) give rise to a mantle plume with a large head and a long-lived conduit or tail, provides a context for interpreting a wealth of surface observations related to LIPs and hotspot volcanism. And, nd, if plumes do originate in the lowermost mantle, they may be the only way to ‘sample’ the deepest part of the Earth’s mantle. Regardless of the origin of LIPs,, studying them and hotspot volcanism provides unique and fundamental information about mantle dynamics, global heat and mass transfer in the mantle, time scales for ‘storage’ of geochemical heterogeneities and, ultimately, mixing eficiency of mantle convection. Over the last decade, our views of mantle plumes have evolved considerably� the ‘mushroom’ shaped plume is certainly possible, but it is not the unique plume morphology. By 6 Scientific Drilling, No. 6, July 2008 Although the nature of compositional heterogeneities in the Earth’s mantle is still a matter of debate (e.g., recycled denser, eclogitic crust� early Earth crust� ancient mantle possibly interacting with the metallic core), many lines of seismological and mineral physics evidence suggesting the presence of chemically distinct, denser material in the lowermost mantle. Therefore, thermo-chemical plumes (i.e., their density contrast with respect to the surrounding mantle depends on both excess temperature and intrinsic composition) provide a new and exciting framework to relate deep mantle dynamics to LIP-forming events and pose a variety of new questions that can be addressed through scientiic drilling. Mantle Temperature emperature �ersus Mantle antle Fertility ertility in LIP Formation ormation A primary question in understanding LIP formation is the extent to which melting anomalies relect excess fertility in the mantle rather than excess mantle temperature. This issue lies at the heart of the current mantle plume debate. Mantle temperature can be addressed through the majorelement composition of primitive LIP basalt via phase equilibria (Herzberg et al., 2007), and studies thereof suggest excess temperatures of <200°C. Mantle fertility is more dificult to investigate because its effects can be mimicked by lower degrees of mantle melting. Diachronous V-shaped ridges around the Reykjanes Ridge south of Iceland (Fig. 3) provide an example of how this problem might be addressed. These ridges relect luctuations in crustal thickness of ~2 km,, and they are caused by pulses in magma productivity radiating outwards from the Iceland hotspot at ~20 cm yr-1. Drilling on the peaks and in the troughs along a transect away from the Reykjanes Ridge will allow basalt composition and hence mantle temperature estimates to be related to crustal thickness. Temperature luctuations should result in an inverse correlation between gravity (a proxy for crustal thickness) and incompatible-element concentrations in basalt because these concentrations will be lower in largerdegree mantle melts. A direct correlation will indicate fertility pulses. A fluctuation luctuation in mantle temperature will cause a correlated luctuation in water depth along the Greenland– Iceland–Faeroes ridge, affecting the low of northern component water southwards from the North Atlantic (Wright and Miller, 1996� Jones et al., 2002� Poore et al., 2006). Sediment drifts south of the Iceland–Faeroes ridge (yellow arrow in Fig. 3) should record variations in this low, and coring these will provide an independent proxy for temperature luctuations in the Iceland hotspot. This synergy between mantledynamic and paleoceanographic objectives will be of considerable mutual beneit. Thermo-Mechanical Mechanical echanical Plume-Lithosphere lume-Lithosphere Lithosphere ithosphere Interaction nteraction with Massive assive Magmatism agmatism The amount of surface dynamic uplift induced by the arrival of a deep mantle plume is being widely debated. Pioneering models (e.g., Farnetani and Richards, 1994) suggested an unrealistically high uplift rate before volcanism, due to the following:: (1) the assumption of purely thermal plumes, (2) poor representation of the lithosphere and the overlying crust, and (3) limited numerical resolution. will establish the thermal or chemical nature of the mantle root, and recovery of basement lava lows from the Eastern Salient will test whether volcanism was extensively subaerial in this area during formation of the OJP (consistent with plume theory), or whether the Site 1184 volcaniclastic sequence was produced by a late-stage volcanic ediice with the bulk of the Eastern Salient being constructed by submarine volcanism. LIP Internal nternal Architecture rchitecture The plume uplift issue is currently being revisited using thermo-chemical plumes, which show a lower vertical velocity component than purely thermal plumes, and thus induce lower strain rates at the base of the lithosphere. Furthermore, the new generation of numerical models incorporatess both a buoyant residual solid in the plume head resulting from partial melting, and surface exchanges of energy and mass between the ascending melts and surrounding rocks. For various plume buoyancy luxes, lithospheric ages, and geodynamic settings, we can now calculate surface uplift/subsidence as a function of time and distance from the plume center. er. r. Model predictions should then be compared with geological observations obtained through drilling. It is important to emphasize that the geologically reconstructed time sequence of surface deformation needs to encompass a time interval extending from a few million years before to a few million years after the main phase of LIP construction. Although drilling typically only scratches the surface of thick igneous basement, it is important to explore the internal structure of a LIP to quantify the relative volumes of extrusive versus intrusive magmatism (Cox 1992� Kerr et al., 1997). Better estimates of total melt volumes and compositions will help to bracket melting rates and to deine melt transport/storage mechanisms between subsurface magma chamber(s) and the surface. Moreover, interactions between partial melts and the surrounding rocks determine the length- and time-scales over which LIP magmatism can change the temperature, the internal loads, and the state of stress of the pre-existing lithosphere and crust. LIPs emplaced in oceanic lithosphere (rather than the thicker and more compositionally complex continental lithosphere) are thus better suited to investigate the thermo-mechanical and compositional modiications induced by LIP magmatism in the lithosphere and the uppermost asthenosphere. Coupling of theoretical predictions with observations will lead to a self-consistent and coherent model of mantle plume dynamics and its thermo-mechanical effect on the overlying lithosphere. The periphery of the Ontong-Java Plateau (OJP) away from its convergent margin with the Solomon Islands may be ideal for this type of study. The OJP represents the world’s most extensive LIP (equivalent to the size of Greenland or western Europe) that, on the basis of current knowledge, formed in ~5 myr at ~122 Ma. It is divided into a High Plateau containing the bathymetric high and a seismically slow cylindrical mantle root extending to ~300 km depth (Richardson et al., 2000� Klosko et al., 2001� Gomer and Okal, 2003) and an Eastern Salient (Fig. 4), with all drill sites encountering igneous basement being located on the High Plateau. Both isostatic (minimum) and dynamic (maximum) crustal uplift were signiicantly less for the OJP than for active hotspots today, and total subsidence is also anomalously less (Neal et al., 1997� Ito and Clift, 1998� Ito and Taira, 2000� Ingle and Cofin, 2004� Roberge et al., 2005) than that of any other known oceanic lithosphere (Parsons and Sclater, 1977� Cofin, 1992� Stein and Stein, 1992). However, to complicate this situation, ODP Leg 192 recovered a sequence of volcaniclastic sediments at Site 1184 on the Eastern Salient that represent subaerial eruptions (Thordarson, 2004)�� this is interesting because this site is not over the mantle root. The sequence was divided into several sub-units separated by wood horizons (Mahoney et al., 2001). Borehole heat low measurements from the High Plateau and Eastern Salient Moreover, we note that the current debate on the role of plumes in the formation of thick, subduction-resisting lithosphere in the Archean will beneit from a better characterization of the density and viscosity structure resulting from LIP volcanism. This may be dificult to achieve directly through scientiic drilling, even with riser capability, although direct 150° 10° 155° 160° 165° 170° 175° 10° East Mariana Basin 5° 5° 807 803 Lyra Basin Nauru Basin 1187 0° 289 0° 1185 1186 ke en Kro nyon Ca 1183 High Plateau Eastern Salient -5° -5° St ew So ar lom on Stewart Basin tA Ellice Basin rch Isla nd s -10° 150° -10° 155° 160° -7 -6 165° -5 -4 -3 -2 -1 170° 175° 0 Predicted Bathymetry (km) Figure 4. Bathymetry of the western Pacific Ocean including features of the Ontong Java Plateau and surrounding basins. Numbered stars represent DSDP Leg 30, ODP Leg 130, and ODP Leg 192 drill sites that penetrated and recovered igneous basement. Scientific Drilling, No. 6, July 2008 7 Workshop Reports results of site survey work, done in preparation for drilling, can directly bear on this question. Plumes and Superplumes: uperplumes: E�ploring �ploring Interactions nteractions with Slabs labs and the Earth�s Core ore Although we generally consider plumes to be isolated ‘bodies’, they are part of mantle convection and are likely to interact with subduction processes and deep Earth dynamics. Plumes upwelling from the thermal boundary layer at the base of the Earth’s mantle could enhance lushing of stagnant slabs into the lower mantle,, and vice versa (Nakagawa and Tackley, 2005). During Cretaceous time, LIP and arc magmatism—which are surface manifestations of mantle upwelling and downwelling, respectively— occurred simultaneously (Reymer and Schubert, 1984� Larson, 1991� Eldholm and Cofin, 2000). Decoding the time relation between magmatism at LIPs and at convergent margins is, therefore, key to understanding the primary cause of mantle convection. Recently, Burke and Torsvik (2004) restored twenty-ive LIPs of the past 200 myr to their eruption sites using a new global paleomagnetic reference model. Ninety percent of the LIPs, when erupted, lay above low-velocity seismic-shearwave regions of the D" zone,, as indicated in current tomographic models, suggesting that the deep mantle beneath the Central Paciic and Africa may represent a long-lived source region for plumes. Better characterization of LIPs will therefore help to understand the nature of ‘superplumes’, their stability over time (�200 myr?), and their potential to sample distinct geochemical reservoirs. By using 2-D numerical simulations, Farnetani and Samuel (2005) have shown the complex internal dynamics of thermo-chemical plumes, leading to the possible coexistence of different types of plumes and superplumes (Fig. 5). dlnVs (%) Finally, the accumulation of cold slabs and the upwelling of hot material induce spatial and temporal variations in heat low at the core-mantle boundary, affecting the outer core Figure 5. 2-D model showing the coexistence of plumes and superplumes in time and space (Farnetani and Samuel, 2005). Colors correspond to calculated seismic velocity anomalies (see inset key for quantitation). 8 Scientific Drilling, No. 6, July 2008 convection and the frequency of polarity reversals (e.g., e.g., low (high) core heat lux, infrequent (frequent) polarity reversals). ).. Courtillot and Olson (2007) showed that three magnetic superchrons preceded the largest Phanerozoic mass extinctions (Cretaceous-Tertiary, Triassic-Jurassic, PermoTriassic), which are associated with major lood basalt events. These authors suggest that thermal instabilities in the D'' layer may increase heat low from the core and trigger the end of a magnetic superchron. Documenting the timing of LIP magmatism and superchron events will provide key information on dynamic linkages between the core and mantle. Geodynamics and Tectonic ectonic Setting etting LIPs are emplaced along active plate boundaries (e.g., magma-dominated divergent continental margins) and in intraplate settings (e.g., continental lood basalts). The tectonic setting of emplacement for most oceanic plateaus and ocean basin lood basalts, however, is not completely understood.. A key question is whether upwelling mantle can erode the lithosphere suficiently to instigate formation of a divergent plate boundary (Hill, 1991� Davies, 1994). While this appears to be the case for the North Atlantic volcanic province, where extension and sealoor spreading relocated from the Labrador Sea to the incipient northernmost North Atlantic coincident with massive North Atlantic volcanic province magmatism (Srivastava and Tapscott, 1986), the situation is signiicantly less clear for other magma-dominated divergent continental margins (e.g., e.g., Northwest Australia and Kerguelen/Antarctica/India/Australia). ).. To gain a thorough understanding of relationships among mantle geodynamics, tectonics, and basaltic magmatism, we need to investigate more than a single example of magma-dominated divergent margins by scientiic ocean drilling. In n marked contrast to the North Atlantic example,, the he Northwest Australian margin is segmented, and igneous rock volumes vary considerably along strike, without clear evidence for a related mantle plume (Mutter et al., 1988� Hopper et al., 1992� Symonds et al., 1998� Planke et al., 2000). This makes the margin a strong candidate to test the edgedriven/small-scale convection hypothesis (Mutter et al., 1988� King and Anderson, 1998� Korenaga, 2004) for generating excessive magma by drilling a margin transect across multiple seaward-dipping relection wedges, the Wallaby Plateau, and normal oceanic crust. The geochemistry, petrology, and geochronology of the recovered rocks will yield melting conditions, mantle reservoir type, extent of continental contamination, and the spatiotemporal evolution of the magma source. The Kerguelen Plateau/Broken Ridge appears to have begun forming in the nascent eastern Indian Ocean at least 10 myr after breakup among Antarctica, India, and southwestern Australia (Cofin et al., 2002� Gaina et al., 2007). Despite these conjugate continental margins exhibiting some characteristics of excessive magmatism during breakup (e.g., e.g., SDR wedges� Stagg et al., 2007) and contemporaneous continental basaltic volcanism (Storey et al., 1992� Frey et al., 1996), ),, the lack of physical and therefore geochronological continuity between these margins and the Kerguelen Plateau/Broken Ridge revealss yet another variation from the North Atlantic example of simultaneous continental breakup and LIP formation. Drilling the Early Cretaceous SDR wedges of the conjugate southwest Indian Ocean margins and the oldest portions of the Kerguelen Plateau to determine geochemistry, petrology, and geochronology will address critical questions involving relationships between geodynamics and tectonic setting. Emplacement tary sequence yields a high-resolution record, this can provide a highly sensitive time indicator of the onset and cessation of LIP activity, directly correlating the LIP with any contemporaneous environmental events. Style and Timing iming of LIP Eruptions ruptions Many eruptions occur during the lifespan of a LIP. For almost all LIPs, the total volumes of lavas are not accurately known, let alone those contained in each eruptive package (or other volcanic deposits such as hyaloclastites). What is also unknown is whether each package was produced by short, intense eruptive episodes, or more pulse-like and protracted ones. Critical for addressing environmental recovery is accurate determination of intervals between eruptions. Drilling into LIPs will provide samples of sediment between lavas to address this (e.g., ODP sites 642 and possibly 807�� Larson and Erba, 1999). The probability of inding chronological and environmental markers (e.g., carbonaceous or siliceous sediment deposition) between low units is much higher in the oceanic environment than on the continents. Erosion during emplacement of submarine LIPs is expected to be minimal� hence, it is more likely to recover lows erupted in sequence. Furthermore, the inal (uppermost) lavas are commonly not preserved in continental lood basalts, but truly submarine LIPs offer a much greater chance of obtaining the full sequence of lava products, or at least the last erupted lavas. Unravelling the emplacement of LIPs is pivotal in understanding their signiicance in the formation of the Earth’s crust as well as any potential environmental consequences. Our understanding of these processes remains quite limited,, and basic questions—such as whether or not the centers ers rs of these eruptions occur along issures—are still matters for debate. Onset of volcanism can be determined for most continental LIPs, although cessation of activity is more problematic to determine due to erosion of uppermost lavas. Oceanic LIPs provide a unique opportunity to address these issues as they are generally better preserved, and consequently can provide a more complete picture of LIP formation. The major issue concerns timing of LIP generation and emplacement (i.e., whether hether the event was short- or long-lived). ). We observe examples of both in almost wholly submarine LIPs and in subaerially emplaced LIPs that have been partly rifted and submerged. This overarching question encompasses several missing links in our present understanding that are immediately addressable by scientiic drilling.. 2) Duration of Emplacement mplacement 3) Many LIPs appear to have at least one major pulse of volcanism when the most voluminous lava sequence was erupted. Identifying the duration of the full sequence of lavas enables identiication of the most voluminous intervals. Knowing the time span of the most voluminous interval(s) for each LIP is crucial for determining the mechanism of emplacement and the potential environmental impact. Furthermore, sampling and dating the lavas allow questions concerning episodicity (about about which we know little in major LIPs)) to be addressed.. For example, was there more than one interval of voluminous volcanism associated with the LIP’s formation? As well as from direct sampling of LIP lavas, much can be learned about the onset and cessation of LIP volcanism from environmental indicators contained in sedimentary sections in older basins adjacent to the LIPs and (potentially) worldwide. These include shifts in isotopic and trace metal content of the sediment that can be linked to the arrival of the irst LIP lavas onto the sealoor and/or (perhaps) volcanic degassing to the atmosphere. If the sedimen- If these two fundamental problems can be addressed, we will be able to answer questions such as: 1) When was as the big pulse or biggest pulses of volcanism during a LIP’s lifespan? Does this is time correlate globally with sudden environmental events? What possible role(s) (s) does LIP emplacement have on these sudden events? Timing of emplacement is critical for determining magma luxes and,, ultimately, the mantle processes controlling magma production. Is magma production in plume heads controlled by ‘bottom-up’ or ‘top-down’ processes? To better understand the possible effects of LIP volcanism being causal for brief but severe environmental crises, it is necessary to determine eruption rates,, and this, in turn, will be useful to model the transport and emplacement distances of lava lows. Consequences of Shallow hallow Intrusions ntrusions Another topical and critical question concerns LIP-related sill emplacement into sediments leading to gas release into the ambient environment� this has occurred on land and on the ocean loor (Svensen et al., 2004). Would submarine gas or luid release directly affect the oceanic environment (Fig. 6)? To better examine relationships between sills and Scientific Drilling, No. 6, July 2008 9 Workshop Reports lava lows, drilling in speciic areas can address the timing of the intrusion of the sills, whether they were the feeders for the lood lavas (see section Duration of Emplacement above) and plumbing systems for LIPs. If the sills and their interactions with sediment cause environmental changes, then it is vital to establish the timing of sill and LIP lava emplacement. Further to the consideration of sills, we know little about magma reservoirs for LIPs, including their locations and dimensions. Are the chambers deep or shallow? Perhaps in oceanic crust, more primitive magmatic material can be erupted at the surface that would otherwise be stalled in continental crust, and a study of this may provide clues to the nature of the initial magmatism related to LIPs. Relationships Between Subaerial ubaerial and Submarine ubmarine LIP Emplacement What are the differences between subaerial and submarine emplacement of LIP lavas, and thus the similarities or differences in LIP architecture between the continental and oceanic realms? In the ocean, very large low ields may be possible underwater,, and perhaps few barriers halt the spread of lava lows. We might thus predict widespread lava ields covering whole provinces, but is this realistic? What do LIP super-eruption products look like when they are emplaced under water? Are the component lava bodies of oceanic low ields similar in dimension to those in continental lood basalt provinces, with low unit thicknesses of 100 m or greater? What is the overall architecture of an oceanic plateau sequence? It appears that their dominantly shallow dipping, low angle slopes would favor the inlation of lava lows (Self et al., 1998). Lava age distributions are also needed to assess how LIPs are constructed. Even though younger, post-major pulse lavas cover most oceanic LIPs, it may be possible to ind widespread main-pulse lavas at the edges of LIPs. Using the architecture of better-known subaerial LIPs (Fig. 7), we can assess where best to drill to intersect long lava lows in submarine LIPs. An important aspect of subaerial versus submarine emplacement of LIPs is the nature of seaward-dipping relectors (SDRs). These are highly signiicant components of several LIPs (such as the North Atlantic and Kerguelen) and not observed in continental LIPs. They are most likely related to the tectono-magmatic setting, but what do they represent? Are they exclusively subaerially emplaced, but subsided parts of a LIP, or might they also form in marine environments? Some geophysical observations suggest the latter, but conirmation by ocean drilling is required. To understand the nature of SDRs, it is crucial to drill full sequences to determine if these were emplaced as deep marine sheet lows, perhaps inilling a subsiding rift basin. LIP-Generated Generated Felsic Magmas Felsic volcanic rocks are typically much higher in potassium than their maic counterparts and thus contain ideal minerals for Ar-Ar dating. Drilling on the Kerguelen B A 10 Scientific Drilling, No. 6, July 2008 Figure 6. Generic version of time vs. volume erupted in a LIP and in LIPs over time (vs. mid-ocean ridges [MORs]): [A] Self et al. (2006) revised volume vs. time for Deccan and Columbia River; [B] Time series for LIPs over the past 200 Ma (Coffin and Eldholm, 1994; Eldholm and Coffin, 2000) with LIPs and MORs to show Cretaceous high-lava productivity period. COLR = Columbia River; NAVP = North Atlantic Volcanic Province; CARIB = Caribbean; KERG = Kerguelen. Solid horizontal bars indicate Cenozoic and Cretaceous mass and other extinction events (after Rampino and Stothers, 1988; Thomas, 1992). Plateau (ODP Leg 183) recovered signiicant amounts of a wide variety of felsic volcaniclastics and lavas (Cofin et al., 2000). Other oceanic LIPs, such as Hess Rise in the Paciic (DSDP Leg 62), contain discrete intervals of felsic lavas. Many, if not all, continental LIPs contain felsic components in the mainseries lavas (Bryan et al., 2002), but not from the Deccan and the Columbia River provinces. Eruptions of these evolved Figure 7. [A] Map of the Columbia Plateau, showing the limits of the Columbia River flood basalts and the magmas can be explosive (e.g., feeder dike systems (dashed lines). CJ indicates the longitudinal boundaries of the Chief Joseph dike swarms that fed the Clarkston (Imnaha, Grande Ronde, and Wanapum) and Saddle Mountain basalts. the Ethiopian ignimbrites) and The Grande Ronde (GR) and Cornucopia (C) swarms are concentrations within the CJ. M indicates the represent valuable stratigraphic Monument dike swarm that fed the Picture Gorge basalt. [B] Ages and estimated volumes of the major and geochronologic markers if eruptive units of the Columbia River basalts. This figure illustrates that surficial sampling of a LIP can yield information on its history of formation. they can be correlated to felsic ash fall deposits in deep sea (CO2 , SO2 , etc.)) or volatiles (CO2 , CH4) from intruded sedisediment (Peate et al., 2003). ments (e.g., .,, carbonates, organic-rich shales, evaporites) Drilling into felsic volcanic products of LIP volcanism, on (Fig. 8). Directly irectly or indirectly,, they may cause changes in the both the LIP proper and in neighboring sedimentary secatmosphere/ocean e/ocean system that lead to perturbations of atmotions, will help anchor the timing of eruptions via sphere/ocean chemistry, circulation, ecology, and biological chronostratigraphy. productivity (Self et al., 2006).. This was especially true in Cretaceous and Early Tertiary time, when the atmospheric Environmental Consequences onsequences CO2 content of the atmosphere was three to seven times higher than that of today (Fig. 9), and perhaps more suscepConnections between large historic basaltic eruptions and tible to short-term perturbations in ocean/atmosphere perturbations of the global environment are well docudynamics and their ensuing effects on life. Furthermore, mented. Classic examples include the eruptions of Laki, recent compilations s suggest that a sudden sea level rise Iceland in 1783, and Eldgjá, Iceland in 934, both of which (~60 m� � Miller et al., 2005)) was associated with the were followed in subsequent years by historically cold sumPaleocene-Eocene Thermal Maximum (PETM) PETM)) event mers in the northern hemisphere (Stothers, 1998). In con(Kennett Kennett and Stott, 1991� Bains et al., 1999� Svensen et al., trast, LIPs represent much larger outpourings of basaltic 2004), , which in turn was concurrent with the formation of magmas over much longer time scales, and recent data the North Atlantic Volcanic Province (Eldholm and Thomas, (Cofin and Eldholm, 1994� Kerr, 1998� Larson and Erba, 1993). . 1999� Leckie et al., 2002� Snow et al., 2005� Kuroda et al., 2007) increasingly suggest temporal correlations between LIP formation and signiicant oceanographic, biotic, and climatic events, the most severe of which are OAEs. Greenhouse gases released from LIP magmas, as well as sedimentmagma interactions and ocean chemistry changes associated with the LIP emplacement, may have had major effects on the global environment (Fig. 1b). Critical in understanding the impact LIP magmatism may have had on the environment is determining LIP volume and, more importantly, magma eruption rates. Scientiic drilling has a vital role to play in identifying the mechanisms and quantifying the timescale and magnitude of effects, and interdisciplinary, synergistic collaborations among scientists from a variety of disciplines are required. Oceanic Ano�ic no�ic Events vents Atmospheric Impacts mpacts of LIP Emplacement mplacement Episodes of complete depletion of oxygen below surface levels in the Earth’s oceans, known as OAEs (Schlanger and Jenkyns, 1976), represent the most momentous environmental changes in the ocean of the past 250 million years, and bear some similarities to the less impactive PETM event. Examples of linked LIP emplacement and major environmental/biological /biological crises include (Fig. 10): ):: Oceanic ic Anoxic Event (OAE)-1a OAE)-1a )-1a 1a in the early Aptian (~122 ~122 Ma) and the Ontong Java Plateau (~120 Ma), Manihiki Plateau (~120 Ma) and the Kerguelen Plateau (~119 Ma)� OAE-2 -22 around the CenomanianTuronian boundary (~94 ~94 Ma) and the Caribbean-Colombian lood basalts (~92–94 Ma)� and the PETM (55 55 Ma) and the North Atlantic Volcanic Province (~55 Ma). LIPs may impact the atmosphere, oceans,, and biosphere by rapidly releasing huge amounts of magmatic volatiles There are two possible ossible causal relationships between LIPs and OAEs:: 1) the instigation of oceanic anoxia through global Scientific Drilling, No. 6, July 2008 11 %FDDBO /
"UMBOUJD $BSJCCFBO .BEBHBTDBS 1BSBOB &UFOEFLB warming by greenhouse gases (e.g., CO2 , CH4) that leads to ocean stagnation, which in turn induces anoxia in deep/ intermediate depths of the ocean� and 2) submarine volcanic eruptions and associated massive hydrothermal release of trace metals into the global ocean instigating black shale events (Snow et al., 2005). Furthermore, the connection between LIPs and marine biotic changess (including some extinctions) has been ascribed to acidiication of seawater by adding CO2 and SO2 (Cofin and Eldholm, 1994� Kerr, 1998). However, these ideas require critical evaluation. ion. 0+1 ,FSHVFMFO Workshop Reports E�ploring Linkages inkages between LIP Emplacements mplacements and Environmental nvironmental Events vents To evaluate linkages between LIP emplacements and environmental events requires information on multiple topics: 1) 2) 3) 4) Accurate and precise timing, duration, and magnitude of LIP magmatic activity and environmental/biotic perturbations� Volatile olatile luxes related to LIP emplacement events (i.e., LIP magma degassing as well as those potentially derived from magma-sediment interactions) and the extent of gas release into the ocean/atmosphere environment� Hydrothermal luid compositions (especially trace metals) and luxes related to LIP emplacement events, and the extent of their release into the ocean environment� Eruptive ruptive environments (e.g., deep/shallow submarine� subaerial) and sediment-magma interactions, as well as the overall tectonic settings, of LIP events� Figure 9. Estimated atmospheric CO2 concentrations during the last 150 myr (Berner and Kothavala, 2001; Tajika, 1998). Shaded areas indicate global oceanic anoxic events (OAE-1a and OAE-2), Cretaceous-Tertiary boundary (KTB), and Paleocene-Eocene Thermal Maximum (PETM). Mass extinctions events (Sepkoski, 1996) are shown as black inverted triangles. 5) Speciic paleoenvironmental conditions prior to, at the onset of, and during times of LIP emplacements (i.e., to deine changes in atmospheric and oceanic physical and chemical properties and circulation). Temporal coincidence between LIPs and environmental crises is clear for a few examples (e.g., North Atlantic LIP, Deccan Traps, Siberian Traps), but temporal correlations between others need further evaluation. Sediment and volcanic rock recovered by the IODP in various oceanic basins and at different paleolatitudes will provide opportunities to resolve these issues in the following ways:: Figure 8. Hypothetical representation of sill-sediment interaction and the release of gases liberated from the sedimentary wallrock. 1 Scientific Drilling, No. 6, July 2008 • Obtaining complete, high-resolution sedimentary records from critical ocean environments (e.g., the Mesozoic pelagic/deep, shallow,, and atoll� sediment from the Paciic, Indian, Arctic, and Southern oceans� and high paleo-latitudinal sites are critically required). • Obtaining syn-sedimentary sections within or adjacent to individual LIPs to estimate the potential hydrothermal luid release and gas release through sedimentmagma interactions. • Targeted drilling to bracket the duration, peak,, and volume of magmatic activity (e.g., tectonic windows and feather edges of LIP basement, and syn-sedimentary sections). • Bracketing the chronology/duration of the environmental events through recovery of sedimentary sections containing carbonates at locations permanently above the carbonate compensation depth, or CCD (e.g., Magellan Rise). New Approaches to Drilling of LIPs Global understanding of LIPs will beneit greatly from new approaches, with drilling as a key investigative tool. Such new approaches, detailed below, include strengthening collaboration with industry� more integrative, multidisciplinary studies� development and deployment of new technologies� and coordinated IODP-ICDP investigations. Industry Connections onnections to Drill LIPs Drilling of LIPs is of interest to the hydrocarbon industry to understand the fundamental processes, in time and space, involved in LIP development and evolution. In particular, interest focuses on how these processes inluence the thermal, structural, depositional, and vertical motion histories of adjacent sedimentary basins (i.e., how LIPs inluence the generation, maturation, and migration of hydrocarbons). Among the various LIP categories, the primary industry interest is magma-dominated divergent continental margins and, to a lesser degree, oceanic plateaus underlain, in whole or in part, by continental crust. Speciic LIPs (e.g., the Norwegian, northwest Australian, and South Atlantic margins) are in regions of interest to the hydrocarbon industry, and ties with industry should be developed to the maximum extent possible. Collaborative IODP–industry LIP investigations could take the form of industry–academia consortia established to address topics of interest to both industry and members of the IODP community using any of the three IODP platforms. Industry contributions to such consortia could include site A B surveying and seismic processing/reprocessing of existing seismic data using sophisticated techniques, as well as inancial support for planning, execution,, and interpretation phases of drilling programs. Joint IODP–industry drilling ventures should address highly ranked scientiic objectives, and the resulting data should be public domain, or offered to the community after a brief participant-exclusive period. Joint, dedicated LIP scientiic drilling ventures provide a means to expand opportunities for scientiic drilling while maintaining IODP scientiic integrity. An Integrated Approach pproach to Drilling rilling LIPs LIP science will be advanced in ive key areas by drilling, with objectives and potential drilling sites outlined below. Obtaining deep sections within multiple LIPs to examine magmatic (and therefore mantle source) variability through time. This will require offset drilling along a rifted LIP margin or into a deep erosional feature within a LIP. Potential locations include (a) conjugate rifted margins of the Kerguelen Plateau and Broken Ridge, Indian Ocean� (b) conjugate rifted margins of the Hikurangi and Manihiki plateaus, Paciic Ocean� (c) Danger Islands Troughs of the Manihiki Plateau, Paciic Ocean� (d) proposed conjugate rifted margins of the Ontong Java Plateau bordering the Stewart Basin, Paciic Ocean� (d) Kroenke Canyon of the Ontong Java Plateau, Paciic Ocean� and (e) lanks of the TAMU Massif on the Shatsky Rise, Paciic Ocean. Note that as one of the oldest oceanic plateaus, Shatsky Rise is an important drilling target for increasing our understanding of the processes that form LIPs as well as how they evolve over time (e.g., subsidence history, secondary volcanism), although basalts from the feature are characterized by MORB-type isotopic signatures (Mahoney et al., 2005). Figure 10. [A] A high-resolution profile of carbon isotopic composition of total organic matter from OAE-2 section from central Italy (Bonarelli Event, colored interval). Data from organicrich (>2% total organic carbon content) and -poor (<2%) sediment are indicated by red and blue symbols, respectively. The profile indicates negative excursion at the base of the OAE-2. [B] A cross-plot of 206 Pb/204 Pb vs. 208 Pb/204 Pb in the Bonarelli (red symbols) and underlying Cenomanian limestone (blue symbols). For comparison, Pb isotopic compositions of basaltic rock from Caribbean (88–95 Ma), Madagascar flood basalts (88 Ma), and from MORB (present) from the Atlantic, Pacific, and Indian oceans are also shown. Both figures are referred from Kuroda et al. (2007). Defining the nature of melting anomalies (i.e., compositional vs. thermal) that produce LIPs. Understanding the underlying mechanics and dynamics of melting anomalies can be tested where basalt composition can be related to crustal thickness or where there is evidence for anomalous mantle beneath a LIP, such as (a) diachronous V-shaped ridges around the Reykjanes Ridge south of Iceland (Fig. 3) in the North Atlantic (see section Mantle Geodynamics above for rationale)� and (b) Ontong Java’s High Plateau, underlain by a 300-km-deep “root” of seismically anomalous mantle that has been Scientific Drilling, No. 6, July 2008 1 Workshop Reports postulated to represent the fossil plume head of the OJP (Richardson et al., 2000� Klosko et al., 2001� Gomer and Okal, 2003). By determining heat low from drill holes above the interpreted fossil plume head as well as away from it, the nature of the melting anomaly can be tested, as numerical models suggest that it should retain a detectable thermal signature. Defining precise durations of oceanic LIP events. Two obvious ways to bracket LIP events are to (a) drill through the oldest and youngest eruptive sequences of a LIP, and (b) core a syn-LIP sedimentary sequence in an older proximal basin. Pursuing option (a) is not feasible by drilling through the entire eruptive sequence of a LIP, but if the age inal eruption can be determined, the age of the start of LIP formation can be approximated by drilling through the lava low sequence at the feather (distal) edge of a LIP. Option (b) will be pursued by drilling syn-LIP sedimentary sequences and analyzing for both age-dateable ash layers and chemical anomalies that are related to LIP formation and/or ash layers (taking into account the varying residence times in ocean water of different elements). Ideally, both options will be pursued. The feather edge of most oceanic LIPs may be drilled providing that it is distal to any volcanic vents and is not tectonic in nature. Examples of syn-LIP sedimentary sections in proximal basins include the following: Kerguelen Plateau: Perth Basin off SW Australia, Enderby Basin and Princess Elizabeth Trough between Kerguelen and Antarctica� Deccan Traps: Western and Northern Somali Basin west of Seychelles, where Deccan basalts crop out� Agulhas Plateau: Transkei Basin between the Agulhas and Mozambique plateaus� North Atlantic Volcanic Province: central and northern North Atlantic, ideally recovering sections through the Paleocene-Eocene Thermal Maximum event� Shatsky Rise: Northwest Paciic Basin west of Shatsky Rise� Ontong Java Plateau: Nauru Basin west of, and East Mariana and Pigafetta basins north of, the Ontong Java Plateau. Moreover, the ~145-Ma Magellan Rise has a carbonate, chert, and black shale (OAE) section (Winterer et al., 1973) encompassing the formations of the Ontong Java, Manihiki, and Hikurangi plateaus. Similarly, the crests of Late Jurassic and Early Cretaceous seamounts in the western Paciic preserve syn-sedimentary sections deposited above the CCD (i.e., carbonate sediments). Defining modes of eruption-constant effusion over several million years or several large pulse events over the same time interval. This will be achieved by a) age dating of discrete 14 Scientific Drilling, No. 6, July 2008 ash layers in syn-sedimentary sections, b) drilling through the feather edge of a LIP reached by only the largest lows— test for age progression, and c) drilling through basement relections interpreted to represent alternating thin and thick lows (Inoue et al., 2008). Establishing relationships among oceanic LIPs, OAEs, and other major environmental changes (e.g., ocean acidification and fertilization). Late Jurassic and Cretaceous OAEs are known to be approximately synchronous with LIP events (Jones and Jenkyns, 2001). Syn-sedimentary sections containing OAE, and bounding intervals are critical for analyses of elemental and isotopic variations associated with OAEs. These data can be compared with similar data from synchronous LIPs. Recovery of OAE intervals at multiple locations around an oceanic LIP allows directionality of luxes to be evaluated. Knowledge of the duration of the LIP event is required for these studies (see above). Technology and LIP Drilling rilling Advances in drilling technology will improve our understanding of LIP origin, emplacement, and environmental impacts dramatically. Speciically, technologies that should either be developed or implemented by the IODP that will advance our understanding of LIPs signiicantly include the following: Enhanced recovery of syn-sedimentary sections, especially those with alternating hard-soft (e.g., chert-chalk) layers. To date, recovery of intercalated hard/soft sediment from the Paciic and Indian oceans has been exceedingly dificult during the DSDP, ODP, and IODP, and poor core recovery precludes recovery of important syn-sedimentary sections. Sidewall coring, important for recovering soft sediment from alternating hard-soft layers. OAEs encompass a maximum of 150 cm of vertical section, although recovery of underlying and overlying sediment is necessary as well for biostratigraphic dating each OAE. Oriented cores. Linking hotspots to LIPs, especially in the Paciic, is hampered because unoriented cores yield only paleolatitude information. Oriented cores are critical for determining sediment magnetostratigraphy in low latitudes, investigating geomagnetic ield behavior, studying plate motions, and establishing low directions of lavas. Riser drilling in >2500 m of water. This will open opportunities for drilling through the feather edges of LIPs to the basement or sediment beneath, thereby bracketing the durations of LIP events. Collaborations between IODP and ICDP LIPs are equally well manifested in the oceans as on land. Questions such as the nature of the mantle source of volcanic plateaus, the ascent of magma from source to surface, magma luxes through the life of a plateau, and the impact of LIP emplacement on global climate are best treated by a joint IODP/ICDP approach. The lessons learned from drilling on variably well exposed continental lood basalts can then be applied to the study of their more spectacular, but less accessible, oceanic counterparts. Proxies of climate change, measured in oceanic and continental sequences, provide information on the contrasting impact of the wholly submarine emplacement of an oceanic plateau and the open-to-theatmosphere impact of continental volcanism. A key target of ICDP drilling should be the sill complexes that presumably underlie most LIPs. These complexes, relatively inaccessible in ocean basins, are important for four reasons. 1) They are an important element in the magmatic plumbing of each LIP. 2) Volatile-release at sill-sediment contacts contributes greatly to climate impact. 3) Valuable deposits of Ni, Cu, and Pt-group elements are located in these sills. 4) Intrusions in sedimentary basins inluence the maturation of petroleum deposits and complicate exploration for such deposits. An understanding of the sill complexes, therefore, has important economic implications, in both continental and oceanic settings. Most importantly, unique and promising opportunities exist for combined IODP/ICDP drilling of the same LIP (e.g., onshore and offshore sections of the North Atlantic Volcanic Province� the Parana-Etendeka lood basalts (South Atlantic)� the Deccan Traps-Seychelles Bank dikes (Indian Ocean)� in situ and obducted (Caribbean, Central and South America) Caribbean lood basalts� Alpha Ridge and the High Arctic LIP� and the Ontong Java Plateau and obducted sections thereof in the Solomon Islands (Paciic Ocean). Conclusions The LIPs workshop was highly successful in showing that studying LIPs requires an integrated approach involving mantle geodynamics, plume modeling, petrology, environmental impacts, paleoceanography, physical volcanology, micropaleontology, geophysics, and tectonics. The workshop also concluded that oceanic LIPs must be studied in concert with their continental counterparts to better understand emplacement mechanism and environmental effects of their emplacement. A number of conceptual drilling targets and prospective regions were identiied. In addition, areas where technology development was needed were highlighted, as were potential LIP-focused IODP-industry and ICDP/IODP collaborations. The result of this workshop will allow focused IODP LIP drilling proposals to be developed. Acknowledgements The authors are grateful for input to this paper by the workshop participants as well as contributors who did not attend the workshop. We thank the IODP and the Consortium for Ocean Leadership for funding. Paul Lyle contributed greatly to the logistics of the workshop and led the ield trip to the Causeway Coast featuring outcrops of the North Atlantic Volcanic Province. We appreciate the reviews of this paper by Jan Behrmann, Christian Koeberl, and Hans Christian Larsen. We thank Kelly Kryc, Therese Lowe,, and Charna Meth for organizing the workshop. References Alibert, C., 1991. 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Coffin, National Oceanography Centre, Southampton, University of Southampton Waterfront Campus, European Way, Southampton SO14 3ZH, U.K. .K. K. Nicholas T. Arndt, Laboratoire de Géodynamique des Chaînes Alpines, Université de Grenoble, Grenoble, France. Robert A. Duncan, College of Oceanic and Atmospheric Sciences, 104 COAS Admin Bldg., Oregon State University, Corvallis, Ore. 97331, U.S.A. Olav Eldholm lm m, Department of Earth Science, The University of Bergen, Allegaten 41, N-5007, Bergen, Norway. Elisabetta Erba, Dipartimento di Scienze della Terra, University of Milan, via Mangiagalli, 34, 20133 Milano, Italy. Cinzia Farnetani, Laboratoire de Dynamique des Fluides Géologiques, Institut de Physique du Globe, Boite 89, 4 pl. Jussieu, 75252 Paris, France. J. Godfrey Fitton, School of Geosciences, 210 Grant Institute, University of Edinburgh, The King’s Buildings, West Mains Road, Edinburgh EH9 3JW, U.K. .K. K. Stephanie P. Ingle, National Oceanography Centre, Southampton, University of Southampton Waterfront Campus, European Way, Southampton SO14 3ZH, U.K. .K. K. Nao Ohkouchi, Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science Technology, 2-15 Natsushima-Cho, Yokosuka, 237-0061, Japan. Michael R. Rampino, Earth & Environmental Science Program, New York University, 1009 Silver Center, 100 Washington Square East, New York, N.Y. 10003, U.S.A. Marc K. Reichow, Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, U.K. .K. K. Stephen Self, Department of Earth Sciences, The Open University, Milton Keynes MK7 6BJ, U.K. .K. K. Yoshiyuki Tatsumi, Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science Technology, Natsushima-cho 2-15, Yokosuka 237-0061, Japan. Workshop Reports Drilling to Decipher Long-Term Sea-Level Changes and Effects—A Joint Consortium for Ocean Leadership, ICDP, IODP, DOSECC, and Chevron Workshop doi:10.04/iodp.sd.6.0.008 by Craig S. Fulthorpe, Kenneth G. Miller, Andr� �. Dro�ler, Stephen P. �esselbo, Gilbert F. Camoin, and Michelle A. Kominz Introduction One of the most societally relevant objectives of the Earth arth sciences is to understand the history and impact of global sea-level (eustatic) luctuations at different timescales. Over a third of the world’s population lives within 100 km of a coastline. One-tenth -tenth tenth of the global population and thirteen percent of the world’s urban population live in coastal areas that lie within just 10 m above sea level (the Low Elevation Coastal Zone or LECZ), which covers only two percent of the world’s land area (McGranahan et al., 2007). Reconstruction of global mean sea level since 1870 indicates a twentieth th century rate of sea-level rise of 1.7 ± 0.3 mm yr−1 and a signiicant acceleration of sea-level rise of 0.013 ± 0.006 mm yr −2 (Church and White, 2006), in part due to anthropogenic inluences. Satellite observations in the last decade show that the rates have increased since 1993 to 3.3 ± 0.4 mm yr-1 (Cazenave and Nerem, 2004). Remote-sensing data suggest that ice sheets currently contribute little to sea-level rise. Best estimates are that sea level could rise by as much as 50 cm in the next 100 years (IPCC, 2007). However, dynamical instabilities in response to climate warming may cause faster ice-mass loss (Cazenave, 2006). Rahmstorf et al (2007) show that sea-level observations are tracking at the high end of the IPCC estimates and conclude that 80 cm, and perhaps >1 m, is the most likely global rise by 2100. In some of the most heavily populated areas (e.g., the U.S. Atlantic seaboard) relative sea-level rise exceeds 4 mm yr-1 (Psuty and Collins, 1996) due to combined effects of global sea-level rise and subsidence. While such rates are gradual on a human timescale, the geological record shows that they can increase rapidly and dramatically (e.g., >2 m in a century� Fairbanks, 1989� Bard et al., 1990)� in addition, the retreat of shorelines can be erratic and rapid even under conditions of moderate global rises of sea level. strain the eustatic response to elevated CO2 levels. For example, determining how sea level varied in response to past intervals of global warming—e.g., —e.g., e.g., marine isotope chrons 5e (Thompson and Goldstein, 2005), 11 (Droxler et al., 2003), 31 (Scherer et al., 2008)� ”mid “ Pliocene warmth (Draut et al., 2003), the middle Miocene climate optimum, the early Eocene (Zachos et al., 2001), and the Late Cretaceous (Abreu et al., 1998� Miller et al., 2005 a, b� Bornemann et al., 2008)— will provide a means to evaluate the eustatic impact of future climate trends. Understanding how processes/mechanisms yield speciic eustatic responses will therefore improve our understanding of the societal impact of the resulting sea-level changes. Furthermore, understanding how process interactions produce the preserved stratigraphy of beds and sequences is fundamental to deciphering the long-term geologic and climatic history recorded by sediments in a variety of marine sedimentary basins. These environments are also economically and strategically important—testing predictive sequence models has a proven potential for identifying oil and gas resources and for ground water/pollution remediation issues. Such research also helps to achieve the long-sought goal of predicting margin lithologies in the absence of drilling, a concept pioneered by the Exxon group (Vail and Mitchum, 1977). Finally, constraining the history of sea-level change provides data of direct use to researchers in other disciplines because of the relationships between Amplit ude (m) 1000 Seaf loor Spr eading 100 I ce Sediment at ion 10 The geologic record provides an opportunity to quantify the timing, amplitudes, rates, mechanisms/controls, and effects (stratigraphic response) of eustatic change (Figs. 1 and 2). This information, in turn, provides a baseline for predicting future global sea-level changes and assessing anthropogenic inluences. In order to understand the effects of potential future eustatic trends, it is vital to document how the Earth arth system has operated during past abrupt climate changes (e.g., the last and penultimate deglaciations) and under past conditions of extreme climate forcing,, and to con- Cont inent al Collison Ther mal Expansion Gr oundwat er & Lakes 1 1 100 10 ky 1 my 100 my Time (years) Figure 1. The mechanisms that generate eustatic change operate on different timescales and generate different magnitudes of sea-level change. These variations in conjunction with proxy data may be used to determine the causal mechanisms of eustatic change. (Modified from Miller et al., 2005a.) Scientific Drilling, No.6, July 2008 19 Workshop Reports eustasy and ice-sheet growth and decay, nutrients and ocean productivity, carbon storage,, and ocean chemistry. The challenge is considerable because eustatic effects are complexly intertwined with processes of basin subsidence and sediment supply (Cloetingh et al., 1985� Karner, 1986� Posamentier et al., 1988� Christie-Blick et al., 1990� Reynolds et al., 1991� Christie-Blick and Driscoll, 1995� Kominz et al., 1998� Kominz and Pekar, 2001). Extracting the eustatic signal requires integrated onshore/offshore drilling transects involving global retrieval of cores representing multiple Sea Level (m) Chron (C) Age (Ma) Polarity Epoch 0 1 Pleistocene 2A 3 3A 4 10 -100 -50 0 50 100 large NHIS late early late 5 5B 20 Pliocene Age -150 Miocene 6 middle early 6C late 8 Oligocene 30 early 12 13 late 16 17 40 Kominz et al. (this(2008) volume) 18 19 20 middle Eocene 21 50 22 23 early 24 25 60 26 late Paleocene 27 28 29 30 70 early ? Maastrichtian 31 32 Campanian 33 80 ? Late Cretaceous Miller et et al. al. Miller (2005) (2005a) Santonian Coniacian 90 ? Turonian 34 Cenomanian 100 34 Oxygen isotopic record (Miller et et al., al., 2005a) 2005) (Miller Albian 110 Error: ±1 my; ±15 m Early Cretaceous Aptian 120 5.0 4.0 3.0 2.0 1.0 0.0 -1.0 -2.0 δ 18O Figure 2. Global sea level (light blue) for the interval 7–100 Ma derived by back-stripping five New Jersey coastal plain core holes (Miller et al., 2005a). Revised back-stripped sea-level cur ve (brown) based on a total of eleven New Jersey core holes (Kominz et al., 2008). Global sea level (purple) for the 18 interval 0 –7 Ma derived from δ O, shown in red for a benthic 18 foraminiferal δ O synthesis from 0 –100 Ma with the scale on the bottom axis (in parts per thousand, Miller et al., 2005a). The Miller et al. (20 05a) back-stripped sea-level curve was smoothed with a 21-point Gaussian convolution filter to generate the smooth black curve. The pink box at 11 Ma is a sea-level estimate derived from the Marion Plateau (John et al., 2004). Light green boxes indicate times of spreading rate increases on various ocean ridges (Cande and Kent, 1992). Dark green box indicates the opening of the Norwegian-Greenland Sea and concomitant extrusion of basalts (Modified from Browning et al., 2008). 0 Scientific Drilling, No.6, July 2008 timeframes and depositional settings, including siliciclastic, carbonate,, and mixed systems (Fig. 3). Fundamental to the approaches recommended by our workshop are as follows:: 1) to enhance our understanding of eustatic timing, amplitudes, rates,, and stratigraphic response during the icehouse period, when glacioeustasy is known to be the principal eustatic mechanism, and� 2) to begin an aggressive program to understand the mechanisms responsible for greenhouse eustasy and how they relate to climatic trends and stratigraphic response. Salt Lake City �orkshop Various groups related to the Ocean Drilling Program (ODP) have developed strategies for studying eustasy on orbital (>19 kyr) and longer timescales (Imbrie et al., 1987� Watkins and Mountain, 1990� JOIDES, 1992). These strategies have begun to be implemented with drilling transects across the New Jersey margin (ODP Legs 150, 150X, 174A, and 174AX), the Bahamas (Leg 166 and mission-speciic platform sites) and a targeted sea-level amplitude experiment on the Marion Plateau, Northeast Australia (Leg 194). However, an effective, coordinated strategy requires that additional margin transects be drilled. In addition, it has been ifteen years since the last of these groups� the Sea-Level Working Group (JOIDES, 1992), discussed goals and strategies of sea-level research. Recent drilling advances, including the use of mission-speciic platforms (MSP) offshore and joint onshore-offshore drilling (e.g., IODP Expedition 313), together with new views on the roles of tectonics and sediment dynamics, required that the scientiic community reevaluate the fundamental assumptions of sea-level studies. As a follow-up to the SEALAIX Symposium (“Sea-Level “Sea-Level Changes: Records, Processes and Modeling”,, September 2006, Presqu’île de Giens, France), ),, an international workshop of more than ifty participants was held in Salt Lake City, Utah (8–10 October 2007) sponsored by Consortium for Ocean Leadership (formerly Joint Oceanographic Institutions), the International Continental Scientiic Drilling Program (ICDP), the Integrated Ocean Drilling Program (IODP), Drilling, Observation and Sampling of the Earth’s Continental Crust (DOSECC),, and Chevron. The purposess of the workshop were ere 1) to review results of ODP and early IODP drilling for sea-level objectives� 2) to reevaluate principles and strategies for constraining genetic links between eustatic change and Earth system processes and for deining the relative roles of eustasy versus local processes in building the stratigraphic record� and 3) to identify possible geographical areas and time-intervals for future IODP drilling transects. Presentations about IODP, ICDP,, and DOSECC were followed by keynote scientiic talks and a series of short, three-minute presentations by participants. Breakout groups subsequently focused on the relationship between recorded sea-level cyclicity and eustatic mechanisms through time,, and on deciphering the stratigraphic response to eustasy through a sedimentary process approach in both Mid-Atlantic Transect B Leg 166, Western Great Bahama Bank Eberli et al. (1997), modified 2 5 3 4 5 3 4 1 2 1 New Jersey Margin A Mountain et al. (2007), modified C Neogene Stratigraphic Signature D The Maldives, West Atoll Chain Bartek et al. (1991), modified Belopolsky & Droxler (2004), modified E Seismic data is courtesy of Fugro F The Gulf of Papua Canterbury, New Zealand (IODP Expedition 321) Tcherepanov et al. (2008, submitted) Lu and Fulthorpe (2004), modified Figure 3. [A] Middle Atlantic Transect (MAT) off New Jersey, showing drillsites targeting a Paleogene-Pleistocene prograding clinoform succession. MAT has been drilled on the slope (ODP Leg 150; sites not shown) and shelf (Leg 174A; sites 1071–1073 along strike from this profile), as well as on the Coastal Plain (Legs 150X and 174AX). Inner shelf drilling (MAT 1-3) is planned as a Mission-Specific Platform IODP Expedition 213. [B] Line drawing of interpreted Great Bahama Bank sequences drilled during ODP Leg 166 (Sites 1003–1005) and the Bahamas Drilling Project (sites Clino and Unda). [C] The stratigraphic signature of the Neogene represented by: 1) late Oligocene-early Miocene aggradation, backstepping and partial drowning; 2) late early Miocene-early middle Miocene vertical growth or aggradation; 3) earliest middle Miocene downward shift of deposition; 4) late middle Miocene systematic lateral growth (progradation); and 5) late Miocene-early Pliocene re-flooding and aggradation (Bartek et al., 1991; Tcherepanov et al., 2008). [D] The Neogene stratigraphic signature along the West Maldives Inner Sea carbonate margin. [E] Neogene stratigraphic signature in the Gulf of Papua. [F] A future sea-level transect: line drawing of interpreted sequences, offshore Canterbury Basin, New Zealand, showing proposed IODP sites, scheduled for drilling as IODP Expedition 317. Scientific Drilling, No.6, July 2008 1 Workshop Reports icehouse and greenhouse worlds. Breakout Group Two was further subdivided into siliciclastic and carbonate groups. In addition to identifying scientiic questions and objectives, the groups were also asked to consider drilling program design, potential target areas,, and technology requirements (onshore and offshore). tectonism (Harrison, 1990).. Sea ea level is important for the study of tectonic processes, because it is the datum against which vertical tectonic movements are measured. 1) Refining timing, amplitudes,, and mechanisms of icehouse (Oligocene-Recent) eustatic change. ODP results to date have demonstrated that global sea-level changes over the past 42 myr can be explained, in part, by growth and decay of continental ice sheets (glacioeustasy� Miller et al., 1996� Eberli et al., 1997� Eberli, 2000). Such drilling has principally addressed the timing of sea-level change and has also determined that sequence boundaries indeed represent timelines as predicted in the sequence stratigraphic model (Eberli et al., 1997� Betzler et al., 2000). Objective 1: Determining Eustatic Mechanisms Understanding the mechanisms that drive eustatic change requires knowledge of the timing, amplitudes,, and rates of global sea-level change (Fig. 1). It also requires information on climate and paleoceanography, mainly derived from proxy records (Fig. 4), and tectonic mechanisms that control the volume of the oceans. In turn, such quantiication of eustatic change will contribute to other areas of the Earth arth sciences by helping to constrain such processes as ice-sheet growth and decay, ocean temperatures, carbon burial, and inorganic carbon precipitation in carbonates (Fig. 4) as well as global However, our understanding of how climate change inluences sea level, even during this “icehouse” period of large ice sheets, is incomplete. In particular, there are still uncertainties surrounding the hierarchy of eustatic and sequence periodicities, and particularly the origins of sequences with durations of >1 myr, which do not appear to conform to long-period Atmospheric transport - Rayleigh fractionation : (1.2 myr and 2.4 myr) astronomiδ O progressively depleted in O towards higher latitudes as a result of precipitation cal variations (Miller et al., 2005a). It is surprising that modupCO2 δ18Owater vapor ~ δ18Osw (ƒ carbon flux) lation by the 1.2-myr-long Con Size of ice sheet tinen tal w and eath 18 erin g an tilt cycle is not a dominant periodδ O ice sheet d ru noff (ƒ pCO2, Tº, altitude) %CaCO3 [shelf] icity in icehouse sea-level records, (ƒ sea-level) Ice sheet because it has been shown that sea-level Iceberg Glacial erosion CO3 [dissolved] the short 41-kyr -kyr kyr tilt cycle domiOrganic proxies ( ƒ Tº) (ƒ weathering) nates the ice-volume record of the δ18OForaminifer δ18 Osw (ƒ δ18Osw , Tº) past 34+ my (Zachos et al., 2001). (ƒ ice volume, evaporation -precipitation) Continental Continental margin Mg/Ca Foraminifer The 2.4-myr -myr myr very long eccentricmargin (ƒ Tº, Mg, Ca) ity cycle dominates carbon isotoCCD (ƒ pCO2, CO32-, %CaCO3 [deep-sea] pic records throughout the %CaC03[shelf ]) (ƒ CCD) Cretaceous to Cenozoic through IRD (ƒ icebergs) its effects on the carbon system,, Sediment cover Seafloor - Open Ocean which might be expected to be Figure 4. Details are given below. inluenced by sea-level changes. Spectral analysis of the Miller Schematic igure illustrating how deep-sea geochemical records can be used to understand mechanisms of et al. (2005a) sea-level records past eustatic changes by analogy to the modern ocean. During atmospheric transport from low to high latitudes shows that variations occur with water vapor becomes progressively more depleted in δ18 O, and ice sheets have a very negative δ18 O signature. The isotopic composition of high latitude ice sheets is a function of the magnitude of isotopic fractionation within an as-yet-unexplained, persistent the hydrological cycle, which in turn is dependent on pCO2 and temperature, and could vary over geological 3-myr -myr myr beat that may be either an timescales. Consequently, the δ18 O composition of seawater (δ18 Osw) is largely a function (ƒ) of ice volume and regional evaporation and precipitation processes. Reconstructing δ18 Osw in different ocean basins will interference between the 1.2 myr highlight times of eustatic changes due to ice-volume luctuations, as well as provide a record of the timing and and 2.4 myr cycles or be an artiamplitude of these changes. δ18 Osw can be derived by combining the isotopic composition of foraminiferal fact of an undersampled sea-level calcite (“δ18 OForaminifer ”) with independent temperature proxies (e.g., Mg/Ca for deep-water temperature, and TEX86 and alkenones for surface water temperatures). Subsequently, correlation of excursions in δ18 Osw to signal. This intriguing relationmore positive values with independent evidence of sea-level change can be taken as support for the operation ship bears investigation because of a glacio-eustatic mechanism. Open ocean sites can also provide more indirect evidences of the relative role of glacio-eustasy through geological time. The presence of ice rafted debris (IRD) in open ocean sediments the million-year-scale sea-level indicates iceberg transport, and thus a signiicant volume of ice at sea level along continental margins. The signal can be shown to be a comwaxing and waning of ice sheets is a function of high-latitude temperatures and atmospheric pCO2, which posite of 41-kyr tilt cycles, at least also impact the position of the carbonate compensation depth (CCD). Fluctuations in the CCD are recorded as variable carbonate contents (%CaCO3) within deep-sea sediments and could be used as indirect evidence for the icehouse world (Miller of glacial/interglacial alternations, as CCD is sensitive to changes in carbonate burial on the shelf. Finally, et al., 2005a). eustatic variations control the area of shelf submerged, thus indirectly impacting the type of rocks subjected 18 18 Evaporation Evaporation High latitude precipitation Precipitation Precipitation low to mid-latitude Evaporation water vapor 2 to continental weathering, the amount of nutrients and carbonate ions delivered to the coastal ocean, and the area available for carbon burial on continental margins. Some isotope systems (Os, Nd, and Sr) are available as proxies of continental weathering. The weathering processes ultimately have feedbacks on the carbon cycle, climate, and glacioeustasy.  Scientific Drilling, No.6, July 2008 Moreover, sea-level amplitudes during this period have not yet been adequately constrained. A) B) One approach for determining eustatic amplitudes that has been applied with success to the New Jersey margin involves combining sequence stratigraphic and back-stripping analyses (Fig. 5� Kominz and Pekar, 2001� 2002� Pekar and Kominz, 2001). The resulting C) sea-level curve (Fig. 2� Dist ance Along The Cr oss Sect ion (km) Browning et al., 2008)) repreO2 O3 O2. 5 O1 ML O4 O5 O6 sents the best current estimate, Eocene but it is still incomplete because lowstand sediments were not recovered, introFigure 5. In order to determine sea-level change from a marginal marine setting, we recommend at least two-dimensional sequence stratigraphic back-stripping. An example of some of the data required for ducing uncertainty to estitwo-dimensional sequence stratigraphic back-stripping from Kominz and Pekar (2001, 2002) is shown for mated amplitudes. Possibly as illustration. [A] Chronostratigraphic chart for New Jersey coastal plain Oligocene sequences. Solid colors a result, the Miocene part of represent highstand systems tracts, while lowstand systems tracts are depicted by patterned colors. Vertical lines show well control. [B] Sequence model for New Jersey coastal plain Oligocene sequences. the New Jersey sea-level curve Patterns and lines as described above. [C] Geometry of horizons identified in A and B after performing does not appear to correspond geohistory analysis. Sequences may be identified by colors, which reflect those in A and B, and the labeled offlap break points (inverted triangles) of the final horizon of each sequence. (Modified from as well to the globally recogKominz and Pekar, 2002.) nized stratigraphic signature of the Neogene as other eustatic curves (Fig. 6� Bartek et al., 1991). Furthermore, the additional drilling for icehouse eustatic objectives. Ideally, New Jersey curve also differs from 18O records that have two-- and three-dimensional back-stripping procedures would been corrected for paleotemperature and are therefore an improve amplitude estimates (Kominz and Pekar, 2001). improved record of ice-volume luctuations (Billups and These approaches require good regional seismic coverage Schrag, 2002� Lear et al., 2004), and which do correspond and a well-constrained, regional, sequence stratigraphic well to the stratigraphic signature of the Neogene (Fig. 6). framework, including data that can only be obtained from cores. Finally, estimates of the amplitudes of eustatic change from one-dimensional back-stripping at one location (e.g., 2) Challenging the paradigm of a stable, ice-free “greenNew Jersey� Miller et al., 2005a� Kominz et al., 2008�� house” climate. Though we are beginning to unlock the mysBrowning et al., 2008)) requires supplemental application of teries of icehouse sea-level changes, our understanding of this procedure to strata on distant continents (e.g., Carter eustatic change during the preceding “greenhouse” world of et al., 1991). Future scientiic drilling must therefore include the Triassic to early Eocene is controversial. For example, the Late Cretaceous has been reconstructed as a greenQueensland Great -100 -100 0 100 200 300 house world with warm polar 200 0 6 5 4 3 2 Plateau Bahama B. 0 BA Haq et al., 1987 C Liesicki & Raymo, 2005 QU 12 climates (Bice et al., 2006), QU 11 Haq and Al-Qahtani, D QU 10 Sea-level fluctuations E 2 1 0 -1 QU 9 2005 E2 and most studies have QU 8 F QU 7 5 5 Miller et al., 2005a 10 assumed the absence of polar G QU 6 3 H 4 4 ice sheets (e.g., Huber et al., 3 I QU 5 Site 747 K QU 4 2 2 L QU 3 1995). However, the work of 20 -2.5 -2 -1 -1.5 M 1 Droxler & Vincent, Exxon Production Research N 1 QU 2 unpubl. Mi1 QU 1 O Company (Vail and Mitchum, P Oi2b 1977� Haq et al., 1987) and 30 P2 Oi1 more recent publications Eberli et al., 1997 Betzler et al., 2000 Site 1218 (Van Sickel et al., 2004� Sequence boundaries, 40 carbonate platforms Miller et al., 2003, 2005a, b� Lear et al., 2004, Billups & Schrag, 2005 Bornemann et al., 2008) have Oxygen isotope variations indicated large (tens of 50 -50 0 50 100 meters), short-period Figure 6. Oxygen isotopic and eustatic curves showing correspondence to the stratigraphic signature of (<1 myr) Late Cretaceous the Neogene (red arrows and numbers 1–5; see Figure 3). The Miller et al. (2005a) eustatic curve from the global sea-level (eustatic) New Jersey margin does not conform precisely to the global signature, particularly in the middle and late luctuations (Fig. 2). In addiMiocene. m.y. Miles 0 5 10 15 20 25 30 35 Age (Ma) e. m. middle late early middle Eocene l ate Oligocene early Miocene l ate P l i o. e. l. P l ei s. Epoch/Age 0 Relat ive Dept h 20 (m) 40 1 0 -1 -2 Scientific Drilling, No.6, July 2008  Workshop Reports tion, second- (~10 my), third- (1–5 my) and fourth- (~0.5 my) order sequences can apparently be correlated widely between tectonically active and passive regions (e.g., Western Interior Seaway, Europe and India� Gale et al., 2002) suggesting eustatic control. Glacioeustasy is the only known mechanism for producing such large, rapid eustatic changes (Donovan and Jones, 1979� Fig. 1). There are two solutions to this enigma: eustatic mechanisms are not fully understood, or there were ice sheets throughout much of the Triassic to early Eocene (Stoll and Schrag, 1996, 2000� Abreu et al., 1998� Miller et al., 2003, 2005a,b� Bornemann et al., 2008). ODP and ICDP drilling onshore New Jersey (Leg 174AX) have provided a detailed record of Cretaceous to early Eocene sequences. This record quantiies high amplitudes and rates of eustatic change (>25 m in <1 myr) in the Late Cretaceous to Eocene greenhouse world. Based on this sea-level history, Miller et al. (2003, 2005a, b) have proposed that ice sheets existed for geologically short intervals (i.e., lasting ~100 ky) during the Late Cretaceous-Eocene. This view can be reconciled with previous assumptions of an ice-free Greenhouse World. orld. Eustatic changes on the 10 6 yr scale were typically ~15–30 m in the Late Cretaceous-Eocene (ca. 100–33.8 Ma), suggesting growth and decay of small- to medium-sized (10–15 x 10 6 km3) ephemeral Antarctic ice sheets (Miller et al., 2005a, b). However, although such indirect evidence for ephemeral ice sheets is growing, there is, as yet, no physical evidence for Late Cretaceous to early Eocene ice sheets. A particular dificulty is that other data indicate warm global temperatures for much of this interval—for example,, very warm Albian-Santonian sea surface temperatures in the tropical Atlantic (Forster et al., 2007). There is therefore a need for additional high-resolution stratigraphic records from the greenhouse period. Objective : Defining Stratigraphic Responses The stratal geometries that deine sedimentary sequences worldwide (Mitchum et al., 1977� Haq et al., 1987) result from a complex interplay of processes acting in three dimensions. Eustasy competes with climatic and paleoceanographic variations, tectonism, rates and modes of sediment supply,, and submarine current activity to inluence base level and shoreline position and,, hence,, stratal formation and preservation. Understanding margin sedimentation, therefore, requires evaluation of multiple processes (including eustasy) at various temporal and spatial scales (Nittrouer and Kravitz, 1995). However, predictive models of the distribution of sediments within unconformity-bounded sequences are based on assumptions about the importance of relative sea-level change (Posamentier et al., 1988� Vail et al., 1991) that have yet to be adequately tested. 4 Scientific Drilling, No.6, July 2008 Nevertheless, various industry and academic studies have established that unconformity-bounded sequences are indeed the building blocks of the stratigraphic record (see summary in Christie-Blick and Driscoll, 1995), as irst proposed by Vail and Mitchum (1977), and that they can occur in predictable patterns (Fig. 3). For example, the geometric signature of stratigraphic sequences along continental margins for the last 30 Ma involves (Fig. 3C–E) (1) late Oligocene (Chattian) and early Miocene (Aquitanian) aggradation, back-stepping and drowning�� (2) late early Miocene (Burdigalian) and earliest middle Miocene (early Langhian) aggradation�� (3) earliest middle Miocene (late Langhian) downward shift of deposition�� (4) middle Miocene (Serravallian) progradation�� and (5) two stacked looding and aggradational episodes in the late Miocene (Tortonian) and early Pliocene (Zanclean) separated by a late Miocene (Messinian) downward shift of deposition (Bartek et al., 1991, Tcherepanov et al., 2008a and b). Although this pattern is widespread and is observed globally in both siliciclastics and carbonates (Fig. 3� Bartek et al., 1991� Tcherepanov et al., 2008a and b), ),, the heart of this section, the early and middle Miocene, has not yet been ground-truthed by drilling. The fundamental assumptions and predictive capabilities of sequence models can only be tested by drilling on shallow continental shelves where (3-D) -D) D) sedimentary geometries are constrained by seismic data (e.g., Kominz and Pekar, 2002). Siliciclastic Margins.. Because of the complex interplay of forcing mechanisms responsible for the stratigraphic record, stratigraphic response must be deined in a diversity of time periods and settings, both tectonic and sedimentary. Siliciclastic sediments are excellent sea-level markers because both highly sensitive indicators of shoreline position,, and they are globally widespread. However, it is essential to deine the speciic sedimentary processes (depositional, transportational,, and erosional) responsible for the stratigraphic record and to distinguish the responses of these processes to eustasy from their responses to local forcing. This process-based approach must be a component of future drilling-based sea-level research. The stratigraphic record comprises both surfaces and intervening sedimentary units. In offshore work, surfaces are often deined initially using seismic relection proiles and later calibrated by coring (Fig. 3). However, only coring can provide the lithofacies and biofacies of the intervening units. Sequence stratigraphic models of such units (Posamentier et al., 1988� Van Wagoner et al.,, 1988� Vail et al., .,, 1991) are based on simple assumptions about how facies respond to relative sea-level changes. However, the real world is rendered more complex by the additional inluence of local forcing and the three-dimensionality of sequence architectures. Future drilling to investigate the stratigraphic response to eustasy must therefore evaluate the contributions of tectonism and sediment supply. In addition, geometrical variations must be constrained by pre-drilling seismic surveys. Carbonate Platforms and Margins. Carbonates are excellent sea-level markers because carbonate facies are depthdependent owing to the importance of sunlight to many carbonate-secreting organisms (Eberli et al., 1997� Camoin et al., 2007a). The relationship of these systems to the carbon cycle allows direct correlation of climatic and eustatic signals (Lear et al., 2004). In addition, multiple dating techniques are available for carbonates (including 14C, U/Th, Sr, U/Pb, biostratigraphy,, and magnetostratigraphy). These ese enable examination of a wide range of frequencies of sea-level change, from millennial scale to tens of millions of years. Continental margin transects (Fig. 3) have the advantage that their stratigraphic architectures are well constrained by seismic data. However, they are complemented by tropical reefs and atolls, which provide the most reliable geological estimates of relative sea level by dating “fossil sunshine” (e.g., shallow dwelling corals). The study of coral reefs is of crucial importance in attempts to resolve the rates of millennial-scale changes in sea level, to clarify the mechanisms that drive glacial-interglacial cycles,, and to constrain geophysical models. Coral reefs provide unparalleled records of sea-level amplitudes, particularly for the middle to late Pleistocene. For example, drilling reefs in Barbados has provided a precise estimate for the last eustatic lowstand (120 ± 5 m below present at 18 ka� Fairbanks, 1989� Bard et al., 1990� Peltier and Fairbanks, 2006). Shallow-water drilling of coral reefs remains challenging due to recovery problems, but is necessary to allow study of recent high-resolution climate changes,, and it contributess to estimates of the future behavior of the Earth system on societal timescales. This approach was employed during IODP Expedition 310 off Tahiti (Camoin et al., 2007a, b). Strategies 1) A focus on both icehouse and greenhouse objectives. 2) Drilling transect approach. This approach, which was tried and tested on the New Jersey Margin and Great Bahama Bank, with additional IODP drilling planned off New Zealand (Fig. 3), must be enhanced and extended by: • • Integration of onshore (e.g., ICDP, DOSECC) and offshore (IODP, DOSECC) drilling. The record of icehouse eustasy is best preserved offshore (e.g., e.g., on continental margins), ),, but the older, greenhouse, record tends to be preserved and drillable beneath coastal plains or in onshore basins (e.g., the Western Interior Seaway). Onshore drilling is therefore expected to play an increasingly important role in sea-level studies. Drilling of suficient boreholes, including multiple transects where necessary, and incorporation of suficient seismic control to constrain three-dimensional stratigraphic architecture. • Maximizing core recovery by using appropriate drilling technology (e.g., casing, mud) and platforms (e.g., Mission Speciic Platforms [MSPs]), and by adapting coring strategies as needed, e.g., by using diamond coring or short advances of the XCB. 3) Recognizing the value of addressing tectonically active settings. For example, the stratigraphic expression of sea-level change in active foreland basins in the U.S. and Canadian western interior basins is superlative, though the stratigraphic records incorporate the effects of both eustasy and tectonism. 4) Incorporating a focus on high-resolution (103 –10 5 yr) glacial-interglacial cycles (e.g., the last 130 kyr). Examination of margins with high stratigraphic resolution will allow evaluation of the interaction of eustasy and other processes (e.g., Papua New Guinea� Jorry et al., 2008), ), and integration with process-oriented -oriented oriented modeling (e.g., physical and mathematical modeling done as part of the Margins and Intermargins Initiatives). 5) Coordination with drilling operations designed to address other objectives. Sea-level studies can beneit greatly from the results of research into, for example, paleoclimate, carbon cycling, and ice-sheet dynamics (Fig. 4). Conversely, these research programs will also gain necessary insights from a well constrained eustatic history. Future �ork Future IODP drilling for sea-level objectives includes IODP Expedition 313, New Jersey inner shelf drilling scheduled for summer 2009 and IODP Expedition 317, Canterbury Basin, New Zealand, scheduled for November 2008–January 2009. Great Barrier Reef drilling is tentatively planned for 2009. These planned expeditions, and existing IODP proposals (e.g., Maldives, North West Australian Shelf, Gulf of Mexico - Southern Bank, Belize margin, Gulf of Papua),, all address icehouse objectives. Such drilling is indeed vital, in particular to constrain icehouse eustatic amplitudes and to calibrate the stratigraphic signature of the Neogene (Bartek et al., 1991). However, the next phase of sea-level studies must include greenhouse objectives. We therefore encourage proponents to prepare and submit sea-level proposals for both offshore and onshore drilling focusing on the greenhouse world. Acknowledgements We thank all of the workshop participants for their contributions in support of scientiic drilling for sea-level objectives. Particular thanks are due to breakout group chairs Andy Gale, John Jaeger, Michelle Kominz, Rick Sarg,, and Bill Thompson. Charna Meth and Julie Farver of the Scientific Drilling, No.6, July 2008 5 Workshop Reports Consortium for Ocean Leadership provided excellent support before and during the workshop. Dave Zur of DOSECC also provided logistical support. Bryan Bracken of Chevron led an outstanding ield trip to Book Cliffs before the workshop, ably assisted by Sunday Shephard and Peter Sixsmith. We express our sincere appreciation for the inancial support of the Consortium for Ocean Leadership, ICDP, IODP, DOSECC,, and Chevron. This joint support enabled us to make the workshop a truly international meeting. References Abreu, V.S., Hardenbol, J., Haddad, G., Baum, G.R., Droxler, A.W., and Vail, P.R., 1998. Oxygen isotope synthesis: A Cretaceous ice-house? In Graciansky, P.-C., Hardenbol, J., Jacquin, T., and Vail,, P.R. (Eds.), Eds.), ds.),, Mesozoic and Cenozoic Sequence Stratigraphy tratigraphy of the European Basins asins. Tulsa, Okla. (SEPM SEPM (Society for Sedimentary Geology)) Spec. 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Fulthorpe, The University of Texas at Austin Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences, J.J. Pickle Research Campus, Bldg. 196 (ROC), 10100 Burnet Road oad d (R2200), Austin, Texas as 787584445, U.S.A., e-mail: craig@ig.utexas.edu. Kenneth G. Miller, Department of Earth and Planetary Sciences, Wright Labs, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, N.J. 08854-8066, U.S.A. André W. Droxler, Department of Earth Science, Rice University, P.O. Box 1892, Houston, Texas as 77251-1892, U.S.A. Stephen P. Hesselbo, Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, U.K. Gilbert F. Camoin, CEREGE UMR 6635 CNRS, BP 80, Europôle Méditerranéen de l’Arbois, F-13545 Aix-enProvence cedex 4, France. Michelle A. Kominz, Department of Geosciences, Western Michigan University, 1133 Rood Hall, 1903 West Michigan Avenue, nue,, Kalamazoo, Mich., 49008, U.S.A. Progress Reports ANDRILL’s Success During the 4th International Polar Year by Fabio Florindo, David Harwood, Richard Levy, and SMS Project Science Team doi:10.04/iodp.sd.6.0.008 Introduction One of the scientiic programs of the Fourth International Polar Year (Allison et al., 2007� www.ipy.org), the ANDRILL (ANtarctic geological DRILLing) Program demonstrated ability to recover high quality marine and glacimarine sedimentary drill cores from high latitude ice-covered areas. ANDRILL’s inaugural 2006 and 2007 drilling seasons resulted in the two deepest drill holes on the Antarctic continental margin, recovering 2,400 meters of high-quality and nearly continuous sediment core. A chief scientiic objective of this collaborative effort of scientists, engineers, technicians, students, educators, drillers,, and support personnel from Germany, Italy, New Zealand, and the United States is the recovery of sedimentary archives from which past climatic and environmental changes in the southern high latitudes can be reconstructed. More than 120 individuals have been involved in each of the two drilling projects, eighty of whom m worked in Antarctica during each austral summer season. operated on the surface of 8.4 m of multi-year sea-ice over a 384-m -m m water column. Alex Pyne, the Drilling Science Manager, merits recognition for the concept, design,, and successful integration of elements of the ANDRILL drilling system. Two Successful Antarctic Seasons Both of the ANDRILL projects reached their scientiic targets. The MIS Project,, led by Tim Naish (NZ) and Ross Powell (U.S.), .S.), S.), .), ),, recovered a record of a dynamic cryosphere of the last 13 million years of glacial and climatic variation of the West Antarctic Ice Sheet and Ross Sea region. The SMS Project (led by the authors of this report) completed drilling operations in late 2007 after recovering an expanded 600-m-thick -m-thick m-thick section of the target interval that recorded a history of ice-proximal, shallow marine paleoenvironmental variation during the middle Miocene. This interval has long been held as a fundamental step in development of the Cenozoic cryosphere—interpretations of deep-sea oxygen isotope records suggest the middle Miocene encompassed a change from a period of warm climatic optima, approximately 17.5 Ma to 14.5 Ma, to the onset of major cooling between c. 14 Ma to 13 Ma, and the formation of a quasi-permanent ice sheet on East Antarctica. Completed in early December 2007, the AND-2A drillcore of the Southern McMurdo Sound (SMS) Project (Figs. 1 and 2) recovered 98� of the 1138.54 m of sedimentary rock penetrated, demonstrating that the ANDRILL drilling system (Figs. 1, 3, 4, and 5) is capable of consistently recovering high quality cores. The AND-2A drillcore is exceeded in depth only by ANDRILL’s irst drill hole AND-1B of the McMurdo Ice Shelf (MIS) Project (Fig. 2),, which reached a total depth of 1284.87 m with similar success of high core recovery. Capable of operating in a range of environmental settings, the MIS Project drilled from an 84-m-thick -m-thick m-thick ice shelf platform in 943 meters of water, and the SMS Project In addition to the 600-m-thick -m-thick m-thick middle Miocene interval (800–223 mbsf), the AND-2A drill core also recovered an expanded lower Miocene section (1138.54 up to c. 800 mbsf) through an interval previously recovered during the Cape Roberts Project and an upper Pliocene to Recent interval (223 mbsf to 0.0 mbsf) that is thinner but correlative to parts of the Upper Neogene section recovered by the ANDRILL MIS Project in drill core AND-1B. Abundant volcanic clasts and tephra layers in the core, also provide the materials to document the 20-million-year -million-year million-year -year year evolution of the McMurdo Volcanic Province including several previously unknown explosive volcanic events. Figure 1. Panoramic image of the ANDRILL drilling rig and science laboratories in Southern McMurdo Sound during late 2007, operating from a 8.4-meter-thick sea-ice platform. Transantarctic Mountains are visible in the background. Scientific Drilling, No. 6, July 2008 9 Progress Reports N Tran s anta rctic Mou ntain s Ross Sea SMS MIS Ross Ice Shelf Figure 2. Satellite image of the McMurdo Sound region, including location of the Southern McMurdo Sound (SMS) and McMurdo Ice Shelf (MIS) drill sites. Other results of the SMS Project include (1) a nearly continuous downhole logging operation, including deployment of a range of tools and a borehole televiewer, to match the excellent core physical (MSCL) and chemical (XRF scanning) properties data collected on-ice� (2) the irst Antarctic in situ stress measurements from hydrofracture experiments conducted near the bottom of the borehole� (3) successful reconstruction and orientation of the core, using physical features, borehole tele-imaging, and a core orienting tool� (4) a robust chronostratigraphic framework, developed through integrated diatom biostratigraphy, magnetostratigraphy, and radiometric dating of volcanic materials, which now provides age control for the drill hole and the network of seismic lines in the western Ross Sea� (5) a vertical seismic proile study with three-component data� (6) the richest Cenozoic macropaleontological resource in East Antarctica, with more than ifty productive marine horizons� and (7) a record of terrestrial and marine temperature variationss from a variety of climate proxies. Future Activities and Planning Programs like ANDRILL can help constraining uncertainties about the future behavior of Antarctic ice sheets and resultant sea-level change. These stratigraphic records will be used to determine the behavior of ancient ice sheets and to better understand the factors driving past ice sheet, ice shelf,, and seaice growth and decay. This knowledge will enhance our understanding of Antarctica’s potential responses to future global climate change. With this in mind, the ANDRILL scientiic and operations teams continue to plan for future scientiic progress using the ANDRILL system through ieldbased site surveys, scientiic planning,, and technological developments. s.. ANDRILL’s capabilities are expanding to operate from an ice shelf platform several hundred meters thick and moving at a rate of more than two meters per day.. The ANDRILL teams are also assessing the feasibility of reentering a drill hole, following relocation of the drilling rig and drill site science facilities. In the meantime, the science team members involved in the MIS and SMS projects are actively studying the drill cores and reporting initial results (Harwood et al., 2006, 2008� Naish, et al., 2007a, 2007b, b, 2008). These results are vital to SCAR’s (Scientiic Committee on Antarctic Research) ACE (Antarctic Climate Evolution) program (www.ace.scar.org),, whose objectives are to integrate geological and paleoclimatic data into climate and ice sheet models to constrain estimates of Cenozoic ice volume variability, and terrestrial and marine paleotemperatures. s.. In support of the 4th IPY’s focus on education and outreach objectives (http://www.ipy.org), http://www.ipy.org), ),, ANDRILL is also engaging and training the next generation of Antarctic geoscientists and educators through exciting and collaborative international research and is taking polar science adventure into classrooms and homes through a stimulating and diverse education and outreach program (http://andrill.org/iceberg). Acknowledgements The ANDRILL project is a multinational collaboration between the Antarctic Programs of Germany, Italy, New Zealand,, and the United States. Antarctica New Zealand is the project operator, and developed the drilling system in collaboration with Alex Pyne at Victoria University of Wellington and Webster Drilling and Exploration xploration Ltd. Antarctica New Zealand supported the drilling team at Scott Base,, and Raytheon Polar Services supported the Science team at McMurdo Station and the Crary Science and Engineering Center. Scientiic support was provided by the ANDRILL Science Management Ofice, University of Figure 3. ANDRILL sediment cores were flown by helicopter daily from the drillsite to the Crary Science and Engineering Center at McMurdo Station. Photo by Lucia Simion. 0 Scientific Drilling, No. 6, July 2008 Figure 4. Diamond-impregnated drilling bits enable the ANDRILL drilling system to recover high-quality core, with up to 98% core recovery through glacial and glacimarine sediments. EGU2008-A-12320. Naish, T., Powell, R. D., Levy, R. H., Florindo, F., Harwood, D. M., Kuhn, G., Niessen, F., Talarico, F., and Wilson, G. S., 2007a. A record of Antarctic climate and ice sheet history recovered. Eos Trans. AGU, 88(50):557–558, doi:10.1029/ 2007EO500001. Naish, T.R., Powell, R.D., and Levy, R.H., 2007b. Initial science results from AND-1B, ANDRILL McMurdo Ice Shelf Project, Antarctica. Terra Antartica, 14(3):111–328. Naish, T.R., Powell, R.D., Barrett, P.J., Levy, R.H., Henry, S., Wilson, G.S., Krissek, L.A., Niessen, F., Pompilio, M., Ross, J., Scherer, R., Talarico, F., Pyne, A., and the ANDRILL-MIS Science Team, 2008. Late Neogene climate history of the Ross Embayment from the AND-1B drill core: culmination of three decades of Antarctic margin drilling. In Cooper, A. K. (Ed.), Antarctica: A Keystone in a Changing World. Proceedings of the 10 th International Symposium on Antarctic Earth Sciences. Washington, DC (The National Academies Press), 71–82. Authors Figure 5. Drilling operations under the ANDRILL drill-rig canopy. Nebraska-Lincoln. Scientiic studies are jointly supported by the U.S. .S. S.. National Science Foundation, NZ Foundation for Research, the Italian Antarctic Research Program, the German Science Foundation,, and the Alfred Wegener Institute. For more information, please visit the ANDRILL website at http://andrill.org. References Fabio Florindo, Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, 605, 00143 Rome, Italy, e-mail: florindo@ingv.it David Harwood and Richard Levy, ANDRILL Science Management Office, and Department of Geosciences, University of Nebraska-Lincoln, 126 Bessey Hall, Lincoln, Neb. 68588-0341, U.S.A., e-mail: dharwood1@unl.edu and rlevy2@unl.edu *The names and affiliations of those SMS Project Science Team members engaged during the SMS Project’s initial core characterization phase can be found at the Web site: http://andrill.org/projects/sms/team.html Related Web Links http://www.ipy.org http://andrill.org http://andrill.org/iceberg http://www.ace.scar.org Allison, I., Béland, M., Alverson, K., Bell, R., Carlson, D., Danell, K., Ellis-Evans, C., Fahrbach, E., Fanta, E., Fujii, Y., Glaser, G., Photo Credits Goldfarb, L., Hovelsrud, G., Huber, J., Kotlyakov, V., Krupnik, I., Lopez-Martinez, J., Mohr, T., Qin, D., Rachold, V., Rapley, C., Rogne, O., Sarukhanian, E., Summerhayes, C., and Xiao, C., 2007. The scope of science for the International Polar Year 2007-2008. WMO/TD-No.1364, Fig. 1: Photo by Simon Nielsen Fig. 2: Satellite image courtesy of Steve Fischbein Fig. 4: Photo courtesy of ANDRILL Figs. 3 and 5: Photo by Lucia Simion Geneva (World Meteorological Organization), 1–79. Harwood, D.M., Levy, R.H., Cowie, J., Florindo, F., Naish, T., Powell, R.D., and Pyne, A., 2006. Deep drilling with the ANDRILL program in Antarctica. Sci. Drill., 3:43–45. Harwood, D.M., Florindo, F., Talarico, F., Levy, R.H., and SMS Science Team, 2008. Initial results of ANDRILL’s Southern McMurdo Sound Project drill core AND-2A: early Miocene to Recent paleoclimate and geological history of the Victoria Land Basin, Antarctica. Geophys. Res. Abstr., 10: Scientific Drilling, No. 6, July 2008 1 Progress Reports The CO2SINK Boreholes for Geological Storage Testing doi:10.04/iodp.sd.6.04.008 by y Bernhard Prevedel, Lothar Wohlgemuth, Jan Henninges, Kai Krüger, Ben Norden, Andrea Förster, and the CO2SINK Drilling Group Introduction Europe’s irst onshore scientiic carbon dioxide storage testing project CO2 SINK (CO2 Storage by Injection into a Natural saline aquifer at Ketzin) is performed in a saline aquifer in NE Germany. The major objectives of CO2 SINK are the advancement of the science and practical processes for underground storage of carbon dioxide,, and the provision of operational ield results to aid in the development of standards for CO2 geological storage. Three boreholes (one injection well and two observation wells) have been drilled in 2007, each to a depth of about 800 m. The wells are completed as “smart” wells containing a variety of permanent downhole sensing equipment, which has proven its functionality during its baseline surveys. The injection of CO2 is scheduled for spring 2008 and is intended to last up to two years to allow for monitoring of migration and fate of the injected gas through a combination of downhole monitoring with surface geophysical surveys. This report summarizes well design, drilling, coring,, and completion operations. Since the publication of the Intergovernmental Panel on Climate Change Report (IPCC, 2005), carbon dioxide capture and storage,, including the underground injection of CO2 through boreholes,, became a viable option to mitigate atmospheric CO2 release. One of the major goals for the immediate future is to investigate the operational aspects of CO2 storage and whether the risks of storage can be successfully managed. CO2 SINK is the irst European research and development project on in situ testing of geological storage of CO2 in an onshore saline aquifer (Förster et al., 2006). Key objectives of the project are to advance understanding of and develop practical processes for underground storage of CO2 , gain operational ield experience to aid in developing a harmonized regulatory framework and standards for CO2 geological storage, and build conidence towards future set in “projects of that kind”. The CO2 SINK site is located near the town Ketzin to the west of Berlin, Germany (Fig. 1). The plan is to inject into a saline aquifer over a period of two years a volume of approximately 60,000 t of CO2 . For this purpose, one vertical injection well (Ktzi-201) and two vertical observation wells (Ktzi-200 and Ktzi-202) were drilled at a distance of 50 m to 100 m from each other (Fig. 1). All three wells are equipped  Scientific Drilling, No. 6, July 2008 with downhole instrumentation to monitor the migration of the injected CO2 and to complement the planned surface geophysical surveys. The injection of CO2 will be interrupted at times for repeated downhole seismics (VSP, MSP), cross-hole seismic experiments,, and downhole geoelectrics. The preparatory phase for CO2 injection started in April 2004 with a comprehensive geological site characterization and a baseline luid monitoring (Förster et al., 2006). This was followed by a baseline 3-D seismic survey (Juhlin et al., 2007) and the development of a drilling and completion concept (Fig. 2) allowing for monitoring during CO2 injection and storage observation. Geological Background The CO2 SINK site is located in the Northeast German Basin (NEGB), a subbasin of the Central European Basin System. The sedimentary succession in the NEGB is several kilometers thick containing geological formations of Permian to Quaternary age, comprising abundant deep saline aquifers. The CO2 will be injected into the Stuttgart Formation (lower lower portion, Fig. 3) of Triassic (Middle Keuper) age, into the southern lank of a gently dipping double anticline. The 80-m-thick -m-thick m-thick -thick thick target formation rests at about 630–710 m depth at a temperature of about 38°C. The formation is made up of siltstones and sandstones interbedded by mudstones deposited in a luvial environment. The reservoir is in sandstone channels as well as levee and crevasse splay deposits. These ese channel-(string)-facies rocks alternate with muddy Figure 1. Location of boreholes at Ketzin industrial park. Meters Figure 2. Schematic concept of Ketzin geology, drilling, and geophysical monitoring including moving source seismic profiling (MSP), vertical seismic profiling (VSP), cross-hole seismics, surface 3-D seismics, and surface and cross-hole geoelectrics using a permanently installed Vertical Electrical Resistivity Array (VERA), and Distributed Temperature Sensing (DTS) (from Förster et al., 2006). lood-plain-facies rocks of poor reservoir quality. A geostatistical approach applied to the reservoir architecture (Frykman et al., 2006) pointed towards variable dimensions of the sandstone bodies and was supported by continuous wavelet transforms on 3-D -D D seismic data (Kazemeini et al., 2008). The Stuttgart Formation is underlain by the Grabfeld Formation (Middle Keuper), which is a thin-bedded mudstone succession with interbedded marlstone, marly dolomite and thin anhydrite or gypsum beds deposited in a clay/mud-sulfate playa depositional environment (Fig. Fig. 3� Beutler and Nitsch, 2005). The immediate caprock of the Stuttgart Formation, the Weser Formation (Middle Keuper),, also is of continental playa type, consisting mainly of inegrained clastics such as clayey and sandy siltstone that alternate with thin-bedded lacustrine sediments, like carbonates, and evaporites (Beutler and Nitsch, 2005). The high clay-mineral content and the observed pore-space geometry of these rocks attest sealing properties appropriate for CO2 capture (Förster et al., 2007). The Weser Formation is overlain by the Arnstadt Formation (Middle Keuper), again of lacustrine character (mud/clay-carbonate playa� Beutler and Nitsch, 2005) with similar sealing properties. The two caprock formations immediately overlying the Stuttgart Formation are about 210 m thick (Fig. 3). Figure 3. Condensed geological profile of the Ktzi 200/2007 borehole. Lithological color code: mudstone (magenta), siltstone (green), sandstone (yellow), anhydrite (light blue). Borehole Design All three wells were designed with the same casing layout,, including stainless production casings equipped with preperforated sand ilters in the reservoir section and wired on the outside with a iber-optical er-optical r-optical cable, a multi-conductor copper cable, and a PU-heating cable to surface (Table 1). The reservoir casing section is externally coated with a ibererr- Table 1. Casing Schemes Depth [m] Diameter [inch] [mm] [lb/ft] Quality Stand pipe 30 24 610 125.5 4140 welded Conductor 150 18 5/8 473 87.5 X56 Buttress-BTC Reserve Casing Connection ca.340 13 3/8 340 54.5 K-55 Buttress-BTC Intermediate 590 9 5/8 244 36 K-55 Buttress-BTC Production String 800 5 1/2 140 20 13Cr80 (outside coating) VAM Top Injection String 680 3 1/2 89 9.3 C-95 (inside coating) TS-8 Scientific Drilling, No. 6, July 2008  Progress Reports glass resin wrap for electrical insulation. A staged cementation program was planned around the application of newly developed swellable elastomer packer and stage cementation downhole tools. This technology was preferred red over perforation work that would have caused unmanageable risks of potential damage of the outside casing cables. The 200-m -m m core sections for detailed reservoir and sealing property investigations were recovered with a 6 " x 4" wire-line coring system using polycrystalline diamond compact (PDC) core bits. The 6 1/4" core hole sections were enlarged to 8 1/2 ", and the wells inally deepened below the reservoir zone to accommodate suficient sensor spacing for installation of behind-casing sensor arrays. Metres below ground level CO2Sink Ktzi-201/2007 Well Construction 24 7/8” @ 30 m 18 5/8” @ 49 m 50 TOC: 69 m 100 Constructing three wells close to each other and with such a dense sensor and cable population requires detailed planning. For this purpose, high-end oilield QHSE (Quality, Health, Safety, Environment) management tools were applied, such as “drill well on paper” (DWOP), hazardous operation identiication, repeated incident reporting, post job analysis, and risk management. 560 3 1/2” Injection Tubing 5 1/2” Production Packer Stage Cementing Tool 150 580 Swell Packer Elements Casing Shoe 9 5/8” 5 1/2” Blank Casing 13 3/8” @ 171 m 200 600 250 Viscous Plug 300 9 5/8” 620 5 1/2” Insulated Casing 350 640 400 Filter Screens Insulated 660 450 Drill Mud TOC:465 m 680 TOC: 675 m 700 Cement 600 Stage Cementing Tool Swell Packer Elements Casing Shoe: 589 m 650 5 1/2” Filter Screens 720 500 550 Drilling and Completion Operations Metres below ground level 5 1/2” Insulated Casing 5 1/2” Filter Screens TOC: 675 m 700 740 5 1/2” Blank Casing Stinger Packoff Float Shoe 750 TD: 755 m 760 TD 755 m Figure 4. Drilling design and well completion of the Ktzi 201/2007 borehole. Yellow line indicates DTS and ERT cables with location of ERT electrodes (yellow pluses). Sandstone reservoir intervals are shown in green. Drill site construction started in December 2006, and the drilling operation commenced on 13 March 2007 with the mobilization of a truck-mounted and top-drive equipped rotary drill rig. All the Ketzin wells were drilled with a shale inhibited KCl-water-based -water-based water-based mud system, with the exception of the top-hole section in the fresh-water aquifers, where a K 2CO3 -water-based system was required by the authorities. Both drill muds were conditioned at 1.05–1.16 gcm -33 density. In order to avoid potential risks from environmental hazards, the project further implemented a “shallow gas” procedure in this well section to avoid spills when the wells would encounter high pressurized shallow gas from the past gas storage activity. For this purpose, the top-hole section of the irst borehole was pre-drilled with a blow-out preventer/ 4 Scientific Drilling, No. 6, July 2008 diverter/gas-lare installation on the rig to capture and control unexpected and sudden shallow gas inluxes. As no stranded shallow gas was encountered during drilling (as as also conirmed by reconnaissance wire-line logging and surface seismic processing), ),, this pilot drilling was consequently skipped for the second and third well. Casing asing (18 18 5/8 ") running and cementation with stinger to surface were ere performed in all three wells without problems. In the following 12 1/4" sections, the wells penetrated the Jurassic aquifer systems in which under-balanced pressure regimes were supposed. All wells encountered a minimum of three loss circulation zones between 366 m and 591 m with cumulative mud losses of 550 m 3 . The addition of medium- to coarse-grained shell grit to the mud cured the loss of circulation and brought the wells safe to the 9 5/8 " casing depth between 588 m and 600 m. The lower part of Weser Formation and the entire Stuttgart reservoir section were cored with a specially designed CaCO3 -water/polymer water/polymer drilling mud (1.1 g cm -33). In the irst well, a total of 100 m core was drilled in thirty-nine core runs,, and an average recovery of 97� was achieved. In the second well 80 meters of core was retrieved in thirty-one runs (100� recovery). In the third well only the top 18 m of the Stuttgart Formation was cored with the same excellent performance. The 6 1/4" core hole section was then enlarged to 8 1/2 ", and the wells inally deepened below the reservoir into the Grabfeld Formation. Stainless steel 5 1/2 " production casings (Fig. 4) were installed and cemented in all wells with sensors and cables on the outside. The cables were terminated and fed pressure tight at the wellhead to the outside through the drilling spool below the casing slips. The cement selected in all casing cementations was standard class-G with fresh water and no additives (SG = 1.98 kg L -1), with the exception of the plug cementation, for which a specially designed CO2 -resistant class-G salt cement was selected. The CO2 injection well was completed with a gas-tight and internally coated production tubing, including a permanent production packer above the injection horizon, a iber-optic er-optic r-optic pressure and temperature mandrel/gauge arrangement above the packer and a wire-line-retrievable subsurface safety valve at 50 m depth below the well head. The optical cables and hydraulic safety valve actuation lines were clamped to the outside of the production tubing and fed pressure tight to the outside at the tubing hanger adaptor below the Christmas tree gate valves. Permanent Downhole hole ole Sensors for Monitoring of CO2 Geophysical monitoring techniques are applied in CO2 SINK to delineate the migration and saturation of injected CO2 (Fig. 2). The injection well and the two observation wells are equipped with state-of-the-art as well as newly developed geophysical sensors. The data from this permanent downhole monitoring will be interpreted in combination with data from periodic seismic monitoring (VSP, MSP, and cross-hole seismics) and periodic luid sampling and well logging (Reservoir Saturation Tool). The following permanent components were installed in the boreholes for scientiic monitoring: • • • • a iber-optic-sensor er-optic-sensor r-optic-sensor cable loop for Distributed Temperature Sensing (DTS� all wells) a two-line electrical heater cable (Ktzi 201/2007, Ktzi 202/2007) a Vertical Electrical Resistivity Array (VERA) consisting of ifteen toroidal steel electrodes, 15-line surface connection cable (all wells) iber-optic pressure/temperature (P/T) sensor, iberoptic surface connection cable (at injection string only). Using the DTS technology, quasicontinuous temperature proiles can be measured on-line along the entire length of the wells with high temporal and spatial resolution (Förster et al., 1997� Büttner and Huenges, 2003). The permanent installation of DTS sensors behind the casing (Hancock Figure 5. Centralizer attached to casing et al., 2005� Henninges string with DTS (left) and VERA cables et al., 2005) offers the (right). advantage of full access to the well during technical operations, which, for example, allows control of the process of casing cementation (Henninges and Brandt, 2007). The borehole temperature data will primarily serve in the delineation of physical properties and of the state of the injected CO2 . To enhance the thermal signal and improve the monitoring of brine and CO2 transport, successive thermal perturbation experiments (Freifeld et al., 2006) will be performed, using the electrical heater cable installed adjacent to the DTS cables. VERA provides data on the CO2 saturation employing the Electrical Resistivity Tomography (ERT) method. Each of the VERA arrays covers an interval of about 140 m centered ered red in the injection horizon and consisting of ifteen electrodes spaced at about 10-m -m m intervals. The P/T-sensor installed at the bottom of the injection string above the packer system will continuously monitor the downhole pressure and temperature changes during injection. Data will be transferred red via optical iber attached to the injection string. The inclusion of the permanent downhole sensors into the well completion required a selection of suitable completion components and procedures. Custom-made casing centralizers were used for outside-casing installation of sensor cables, for centralization ation of the casing inside the borehole, and for protection of cables from mechanical damage during installation (Fig. 5). The 8 1/2 " borehole diameter in the lower reservoir sections allowed for suficient clearance within the annular space between casing and borehole wall and thus for a safe fee installation of the downhole sensors. Within the 140-m -m m zone, where the VERA electrodes are placed, the steel casing was electrically insulated outside using a iberglass erglass rglass coating. After an on-site installation test had been conducted, the installation of the DTS and VERA cables (Fig. 5) and electrodes in the Ktzi 200, 201, and 202 wells was performed on 5 May,, 5 July, and 18 August 2007. After careful installation operations of up to 18–24 h duration, the cables were Scientific Drilling, No. 6, July 2008 5 Progress Reports guided into the substructure of the drill rig,, and the casing was cemented. The DTS monitoring allowed online monitoring and control of the cementing operations and provided valuable information about the positions of the cemented sections during the setting of the cement. This information was veriied by subsequent industry-standard cement-bond logs. The installation of monitoring tools was inished by feeding the cables into the casing spool at the wellhead, which was subsequently pressure-sealed using a stufing box. Preliminary tests of VERA have shown that all electrodes and cables are fully functional. The geological description of core started with the sections of well-cemented mudstone after its cleaning with synthetic formation water, reorientation, and scanning unrolled using an optical core scanner. Later, the “hot-shot” reservoir sections were included. From the geological core and cutting descriptions and interpreted petrophysical well logs, stratigraphic-lithologic logs (Fig. 3) were inally generated for all three CO2 SINK wells to reine the geological model. For example, the stratigraphic-lithologic logs were used to calibrate the 3-D seismic time sections (Juhlin et al., 2007). Petrographical and mineralogical studies and geochemical analyses from reservoir and caprock were performed to characterize the Ketzin site on micro-scale as a basis for luid-rock-alteration modeling. Field Laboratory Outlook The CO2 SINK ield laboratory comprised core-cleaning and core-sealing facilities, a full core imager, and a Geotek tek ek gamma-ray density core logger. The ield lab was designed to record and describe a high core-run volume within a short handling time to quickly generate the litholog for the drilled boreholes and to identify the reservoir section. This procedure was necessary in order to proceed rapidly with decision making on the selection of the borehole intervals completed with ilter casings through which the CO2 would be injected into the formation or monitored. In the preparation for unconsolidated sandstone in the Stuttgart Formation, coring was performed with PVC liners in 3-m -m m liner intervals. At the drill rig, liners were cut after orientation marking into 1-m -m m sections,, and the cut surface geologically described was sealed before being transferred to the ield lab for analyses. Sections containing sandstone were shipped preserved in liners to a commercial laboratory for “hot-shot” poro-perm analysis. Reservoir sandstone intervals (Fig. 6) with porosities on the order of 20�–25�, �–25�, –25�, together with requirements for permanent ERT sensor arrangement on the casing, guided the depths at which the wells were completed with ilter screens for CO2 injection and monitoring. Figure 6. Core image of reservoir sandstone showing cross-bedding. 6 Scientific Drilling, No. 6, July 2008 CO2 SINK is the irst project that extensively uses behind-casing installations for a study of the CO2 injection and storage process in a geological medium. In this regard, CO2 SINK differs from other scientiic projects of CO2 test storage, such as the Frio experiment in Texas (Hovorka et al., 2006), the Nagaoka experiment in Japan (Kikuta et al., 2004), the ield test in the West Pearl Queen Reservoir in New Mexico (Pawar et al., 2006), and the Otway Basin pilot project in Australia (Dodds et al., 2006). It is envisaged that the extensive set of data generated by cross-correlation of seismic surface monitoring, well-logging and monitoring, and simulations, will allow for veriication of a priori scenarios of storage/migration of luids. Emphasis, for example, will be given to the observation of non-isothermal effects in the storage formation during injection as described by Kopp et al. (2006). This type of effect also can occur during leakage from a storage reservoir along a fracture zone as numerically investigated by Pruess (2005). Thus, the observations in progress will contribute to a sound understanding of the thermodynamic processes of CO2 injection at well-scale as well as in the short and longer term the processes during CO2 storage at larger scale. Acknowledgements s We would like to thank all partners of the CO2 SINK project for their continued support and contributions that helped to inish the three wells in a healthy and environmentally safe manner. Special thanks go to Shell International and StatoilHydro for their most valuable advice and operational support during the planning and drilling phase in Ketzin.. Furthermore,, thanks go to VNG AG for letting us use their site at Ketzin and for their local logistical support on site. The CO2 SINK project receives its funding from the European Commission (Sixth Framework Program, FP6) and two German ministries, the Federal Ministry of Economics and Technology (CO2 -Reduction-Technologies for fossil fuelled power plants, COORETEC Program),, and the Federal Ministry of Education and Research (Geotechnologien Program). References Beutler, G., and Nitsch, E., 2005. Paläographischer Überblick. In Beutler, G. (Ed.), Stratigraphie von Deutschland IV, Keuper. Stuttgart (Courier Courier ier Forschung-Institut ung-Institut -Institut itut Senckenberg, 253), ), 15–30. Büttner, G., and Huenges, E., 2003. The heat transfer in the region of the Mauna Kea (Hawaii) – constraints from borehole temperature measurements and coupled thermo-hydraulic modeling. Tectonophysics, 371:23–40. Dodds, K., Sherlock, D., Urosevic, M., Etheridge, D., de Vries, D., and Sharma, S., 2006. Developing a monitoring and veriication scheme for a pilot project, Otway Basin, Australia.. 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Evaluation of cement integrity using distributed temperature sensing. Proceedings Engine Workshop 4 “Drilling cost effectiveness and feasibility of hightemperature drilling”, ISOR, Reykjavik, Iceland, 41p. p.. Henninges, J., Schrötter, J., Erbas, K., and Huenges, E., 2005. Temperature ield of the Mallik gas as hydrate occurrence – implications on phase changes and thermal properties. In Dallimore, S.R., and Collett, T.S. (Eds.), Scientific Results from the Mallik 2002 Gas Hydrate Production Research Well Program, Mackenzie Delta, Northwest Territories, Canada, Geological Survey of Canada, GSC Bulletin, 585:CD-ROM. Hovorka, S.D., Benson, S.M., Doughty, C.K., Freifeld, B.M., Sakurai, S., Daley, T.M., Kharaka, Y.K., Holtz, M.H., Trautz, R.C., Nance, H.S., Myer, L.R., and Knauss, K.G., 2006. Measuring permanence of CO2 storage age ge in saline formations – The Frio experiment. Environmental Geosciences, 13:103–119. IPCC, 2005. IPCC Special Report on Carbon Dioxide Capture and Storage. Prepared by Working Group III of the IPCC [Metz, B., Davidson, O., de Coninck, H.C., Loos, M., and Meyer,, L.A. (Eds.)]. Cambridge (Cambridge Cambridge University Press), ),, 442 pp. Juhlin, C., Giese, R., Zinck-Jørgensen, K., Cosma, C., Kazemeini, H., Juhojuntti, N., Lüth, S., Norden, B., and Förster, A., 2007. 3D baseline seismics at Ketzin, Germany: the CO2 SINK project. Geophysics, 72(5):B121–B132. (5):B121–B132. 5):B121–B132. ):B121–B132. :B121–B132. B121–B132. 121–B132. –B132. B132. 132. Kazemeini, H., Juhlin, C., Zinck-Jørgensen, K., and Norden, B., 2008. Application of continuous wavelet transform on seismic data for mapping of channel deposits and gas detection at the CO2 SINK site, Ketzin, Germany. Geophysical Prospecting, accepted. ed. Kikuta, K., Hongo, S., Tanase, D., and Ohsumi, T., 2004. Field test of CO2 injection in Nagaoka, Japan. Proceedings GHGT-7 Conference, Vancouver, Canada, CD-ROM. Kopp, A., Bielinski, A., Ebigbo, A., Class, H., and Helmig, R., 2006. Numerical investigation of temperature effects during injection of carbon dioxide into brine. Proceedings GHGT-8 Conference, Trondheim, Norway, rway, way, CD-ROM. Pawar, R.J., Warpinski, N.R., Lorenz, J.C., Benson, R.D., Grigg, R.B., Stubbs, B.A., Stauffer, P.H., Krumhansl, J.P., and Cooper, S.P., 2006. Overview of a CO2 sequestration ield test in the West Pearl Queen reservoir, New Mexico. Environmental Geosciences, 13(3):163–180. (3):163–180. 3):163–180. ):163–180. :163–180. Pruess, K., 2005.. Numerical simulations show potential for strong nonisothermal effects during luid leakage from a geologic disposal reservoir for CO2 . In Faybishenko, A., Witherspoon, P.A., and Gale, J. (Eds.), Dynamics of Fluids and Transport in Fractured Rock, Geophysical Monograph Series 162, Washington, DC (American American Geophysical Union), ),, 81–89. –89. Authors Bernhard Prevedel, Lothar Wohlgemuth, Jan Henninges, Kai Krüger, Ben Norden, Andrea Förster, GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473 Potsdam, Germany, e-mail: prevedel@gfz-potsdam.de, and CO2SINK Drilling Group: Ronald Conze, Knut Behrends, Erik Danckwardt, Jörg Erzinger, Tor Harald Hanssen, Jochem Kück, Dana Laaß, Andre Mol, Fabian Möller, Peter Pilz, Mathias Poser, Manfred Rinke, Cornelia Schmidt-Hattenberger, Birgit Schöbel, Jörg Schrötter, Hartmut Schütt, Gerardo Stapel, Thomas Wöhrl, Hilke Würdemann, and Martin Zimmer. Related Web Links http://www.co2sink.org/ http://www.icdp-online.org/ http://www.gfz-potsdam.de/ Photo Credits Fig.. 1.. VNG - Verbundnetz Gas AG, Leipzig, Germany Fig.. 5.. Silvio Mielitz, GeoForschungsZentrum Potsdam, Germany Scientific Drilling, No. 6, July 2008 7 Progress Reports The First D/V Chikyu IODP Operations: Successful Logging and Coring During NanTroSEIZE Stage 1 Expeditions Shin’ichi Kuramoto, Daniel Curewitz, Moe Kyaw Thu, Hideki Masago, and the Exp. 314, 315, and 316 Science Parties doi:10.04/iodp.sd.6.05.008 The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a multi-expedition IODP drilling project aimed at drilling, coring, logging, and instrumenting the seismogenic zone of an active subduction margin , in a region thought to generate megathrust earthquakes of magnitude >8.0 8.0 on the moment-magnitude scale (Tobin Tobin and Kinoshita, 2006). The Nankai Trough, offshore of the Kii Peninsula, Honshu, Japan (Fig. 1) was chosen as the location for this project based on a number of scientiic drilling proposals to IODP. These reviewed existing drilling data in the region, the long-term historical and recent record of great earthquakes, the social and societal relevance of the area, and the accessibility of the seismogenic zone to present drilling technology. The irst stage of this multi-stage project was intended to accomplish a broad characterization of the shallow geology, geophysics, physical properties, heat low, and luid low in a transect across the downgoing Philippine Sea Plate, the toe of the Nankai accretionary prism, the megasplay fault zone region on the continental slope, and the Kumano Basin that lies between the accretionary prism and the Kii Peninsula, on the continental shelf (Fig. 2). Between September 2007 and February 2008, IODP Expeditions 314, 315, and 316 were carried out in order to complete Stage 1 of the NanTroSEIZE�� operations included Logging While Drilling (LWD), coring, and downhole measurement at eight sites (thirty-three thirty-three holes) in the Nankai Trough accretionary prism. On 21 September 2007, Chikyu 35° N km 0 50 Izu 40˚N Kii Peninsula 30˚ 130˚ 140˚ 150˚E 34° 75 26 5 3 ne Inli e 24 n Inli Kumano Basin 8 2 000 000 1 dC e C 00 an 007 Sit te C0 004 0 C Si te C0 nd Si 6a 3 000 000 eC t C i e S it Area of 3-D survey S 33° gh ai ank u Tro 136° After 138 days of continuous operations, Stage 1 operations were completed on 5 February 2008. The overviews of each operation as well as the overall accomplishments of Stage 1 are described below. Preliminary reports for each of the expeditions have been published and posted on the Web eb (http://www.iodp.org/scientiic-publications/). Expedition 314: LWD Transect Expedition 314, NanTroSEIZE Stage 1 LWD Transect, was planned to obtain a comprehensive suite of geophysical logs and other downhole measurements at six primary sites along a transect: two on the incoming plate,, two through major active thrust faults, and two pilot holes for deeper riser drilling that also address scientiic targets in the splay fault thrust sheet and the Kumano forearc basin and underlying prism. Due to the dificulties experienced during attempted wireline logging and relatively higher success during limited LWD operations in previous accretionary prism drilling within ODP, Expedition 314 was entirely dedicated to the LWD effort. LWD tool selection focused on maximizing scientiic returns from the tools and the time needed for deployment. The LWD tools used during Expedition 314 were state-of-the-art industrial tools,, and this expedition marked the irst ODP/IODP use of check shot interval velocity, and sonic velocity, and density/porosity measurements while drilling tools that have only been used on very limited occasions. Philippine Sea plate (Shikoku Basin) N 135°E left Shingu port, Wakayama Prefecture, Japan, for her irst scientiic voyage as an IODP drilling platform. The start of NanTroSEIZE operations took place seven years after the irst scientiic proposals were submitted (see Kimura et al., 2003� Kinoshita et al., 2003� Suyehiro et al., 2003� Underwood et al., 2003� Screaton et al., 2005), and marked ed the culmination of thousands of hours of preparation and planning by a Project Management Team (PMT), the IODP Science Advisory Structure (SAS), and the CDEX engineers, technicians, and marine workers. 137° 138° 139° Figure 1. Location of drilled sites during NanTroSEIZE Project Stage 1 in the Nankai Trough off Kumano. Gray box = location of the 2006 three-dimensional seismic survey, black lines = 3-D inlines 2435 and 2675 (see Figure 2), red circles = location of drilling sites. Inset shows location of Nankai Trough. 8 Scientific Drilling, No. 6, July 2008 The operational plan included one-third of the total days (22.5 days out of 57 days) for contingencies ies (typhoons, mechanical downtime) and casing operations. Six primary and two contingency sites were planned for the expedition with the drilling order determined by scientiic priority and SE NW ted) rojec 2 (p C000 2 1 C000 BSR IL 2675 ) cted je 3 (pro 4 C000 008 C0 IL 2435 C000 3 006 C0 0007 C 4 Depth (km) operational dificulty. The he location of planned sites and the order of drilling changed after the team faced ed various challenges. Allotted contingency days were consumed by expected mechanical downtime caused by the strong Kuroshio Current lowing through the area, by dificult drilling conditions, and by unforeseen mechanical and operational events. 5 6 décollement lay -sp 7 ga me t nic crus top ocea 8 2 km VE ~ 2.15X Figure 2. NW-SE slice through the NanTroSEIZE 3-D seismic survey (composite of 3-D Inlines 2435 and 2675) showing the projected locations of the sites, cored and logged during Stage 1. (Moore et al., 2007) During the eight-week LWD campaign, various measurements were successfully completed at four of the twelve total drilled holes, monitoring data. Additionally, these data provide a starting with LWD data coverage ranging from 400 mbsf to 1400 mbsf point for addressing questions raised about current models (Fig. 3). Tool failure, loss of the Bottom Hole Assembly of the margin, including the composition and physical (BHA) due to borehole collapse, and pilot hole drilling characteristics of the stacked thrust sheets comprising the (required for operational safety) consumed the remaining prism, the distribution and character of the faults bounding drilling time and accounted ed for the eight holes not fully the structural blocks and thrust sheets, information about logged. Logging data were initially analyzed by the shipthe stress state in different areas across the margin, the board scientists during the expedition in order to make the distribution and occurrence of gas hydrates,, and the LWD data available to the scientiic parties of the subsequent characteristics of the sediments deposited in both the NanTroSEIZE Stage 1 coring expeditions (Exp. 315, 316). ancient, transported rocks and the more recent sediments During the expedition, the shipboard science party worked draping the margin. Drilling of Sites C0001 and C0002 will in four groups:: log characterization and lithologic also provide pilot hole information important in preparation interpretation, physical properties, structural geology and for the planned deep-riser sites for later stages of geomechanics, and core-log-seismic integration using NanTroSEIZE drilling.. various applications for log and seismic data analyses. Expedition 315: Megasplay Riser Pilot The principal results of Expedition 314 reveal a wealth of information about the accretionary prism, and provide a strong foundation for future planning of NanTroSEIZE, analysis of cores, downhole measurements, and observatory " $ # IODP Expedition 315 took place between 16 November and 18 December 2007,, planned as a geotechnical and scientiic pilot study for future riser drilling of the megasplay fault (Fig. 2). Borehole LWD data obtained during Expedition 314 was available for use during Expedition 315�� this proved extremely beneicial in planning for drilling, coring,, and sampling of the scheduled operations. The operational plan for the expedition was to drill and core to 1000 mbsf at site C0001, a site considered for future riser drilling, then install riser top-hole casing in the latter half of the expedition. However, the Kuroshio Current was deemed to be running too strong (3–5 knots) to safely install the 36-inch and 20-inch casing strings required for the riser pilot. Drilling and operation plans were changed, and Expedition 315 was devoted to coring and downhole temperature measurement at two sites, C0001 and C0002 (Figs. 1 and 2). Figure 3. LWD drilling operations during Expedition 314. [A] Real time monitoring in the lab area; [B] LWD toolstring on the rig floor; [C] Driller’s house operations. Scientific Drilling, No. 6, July 2008 9 Progress Reports Coring at C0001 was conducted with the foreknowledge that the borehole conditions might deteriorate quickly at or near 500 mbsf, in the same formation that proved so dificult during Expedition 314 and where caving and borehole collapse resulted in the loss of the LWD BHA. Coring commenced with HPCS (hydraulic piston coring system) from the sealoor, and obtained good core recovery down to 230 mbsf, at which point coring was conducted using the ESCS (extended shoe coring system). Core recovery by HPCS was good (75�–90�)� �–90�)� –90�)�� however,, core quality using the ESCS was quite poor, and RCB (rotary core barrel) coring then commenced. Using the results of LWD, we expected to encounter a zone of drilling dificulty and borehole instability around 450–600 mbsf. Accordingly, the strategy was to wash down to and through this formation and try to core the formations below that. We succeeded in drilling down to the target depth� however, caving and borehole collapse began nearly immediately, precluding attempts to core below the unstable region. prism off the Kii Peninsula. In addition, the expedition xpedition proved to be invaluable in terms of improving drilling, management, and laboratory performance under harsh weather, strong current, and unfavorable operational conditions. The drilling conditions encountered at intermediate depths at C0001 and C0002 provide important constraints on riserless drilling operations in the fractured and faulted formations that comprise much of the shallow prism, and they will provide data necessary to plan future drilling, coring,, and casing operations. Critical scientiic data was acquired from the upper part of the accretionary prism at both sites, including geological (lithology, structure, and age), geotechnical (physical properties, temperature) and geochemical information for the accretionary prism materials (Fig. 4). These data will help planning for the engineering and scientiic aspects of future riser drilling. Because riser top-hole casing operations were postponed due to the intense current, Site C0002 in the Kumano Basin was chosen for coring, and it was decided that the deeper section was the most critical target. RCB coring began after drilling down to 475 mbsf, and sixty-six cores were collected from that point down to the total depth. We penetrated the basal unconformity of the Kumano basin at 922 mbsf and continued more than 100 m into accretionary prism materials with moderate recovery. As borehole conditions steadily worsened deeper in the accretionary prism, the hole was abandoned at 1057 mbsf. Two short coring operations using the HPCS system were conducted between the sealoor and 204 mbsf for both geotechnical investigations and for scientiic data collection. IODP Expedition 316 drilled several sites in a transect across the outer part of the Nankai accretionary prism. The aims of the expedition were to characterize the sedimentology, stratigraphy,, and physical properties of the slope sediments, the accretionary prism rocks,, and the underthrust material, and to sample and understand the character of fault rocks within fault zones controlling the geometry and evolution of the accretionary prism. As the irst coring expedition for the Chikyu, Expedition 315 provided valuable scientiic and geotechnical data that will be critical in understanding the Nankai accretionary " Figure 4. Coring and laboratory operations during Expedition 315. [A] Core barrel being laid out on the drill floor prior to removal of the collected core. [B] Laboratory technicians cutting a core into sections and collecting safety and time-sensitive samples prior to delivery of core section to the core lab. [C] Core section being run through the X-ray CT scanner. [D] X-ray CT image of a small fault zone cutting across interbedded mud (dark areas) and sandy ash (bright areas). # $ 40 Scientific Drilling, No. 6, July 2008 Expedition 316: Shallow Megasplay and Frontal Thrusts We targeted two major structures: the frontal thrust (sites C0004 and C0008) and the shallow portion of the megasplay fault zone (sites C0006 and C0007) near its intersection with the sealoor (Figs. 1 and 2). Comprehensive sampling and measurement both in boreholes and on core materials were carried out, including downhole temperature measurements, interstitial water sampling, microbiological sampling, gas sampling, and a wide array of sampling for chemistry, mineralogy, and physical properties. More than 1300 meters of core were recovered using HPCS, ESCS, and RCB. More than 5000 samples were taken from the cores for shore-based -based based investigation, and many thousands of continuous and discrete measurements were carried out using the array of laboratory tools on board the Chikyu. % We successfully recovered a wide array of fault rocks from fractured rocks to breccia to fault gouge, sedimentary materials ranging from ine clay and mud to siltstone and sand, and we managed to recover extremely coarse grained materials from paleo-trench-axis channels. Materials sampled include recent slope apron/slope basin deposits (including several mass transport complexes that may shed light on the periodicity of slope failure), ancient accretionary prism rocks, and material that has been over-ridden during thrust faulting events (Fig. 5). Analyses of these wide-ranging data sets will shed new light on the evolution, structure, and architecture of the Nankai accretionary prism off the Kii Peninsula. # Overview and Primary Accomplishments " Chikyu accomplished an $ LWD and two coring expediFigure 5. Coring results, coring operations and laboratory work during Expedition 316. [A] Core recovery tions in a transect across the during Exp. 316. [B] Drill pipe being disconnected immediately prior to removing a core. [C] Composite Nankai Trough accretionary showing CT image, split core surface, and detail photos of fault zone material. prism, gathering large volumes of data, cores, and samples that downhole temperature measurement tools, and extensive will help understand the structure and mechanics of the use of X-ray ray ay Computed Tomography (XCT, Fig. 6) on whole shallow accretionary prism, and that will aid in planning and core sections. The use of XCT scanning in particular proved carrying out future deep drilling to the shallow part of the to be an exciting and revolutionary addition to the scientiic lying 6–7-km-deep -km-deep km-deep -deep deep seismogenic zone. drilling, as it allows inspection of core before any destructive measurement or sampling is carried out, provides real-time Expedition 314 (LWD Transect) collected 4274 m of LWD guidelines for sampling and handling before the core is split, logs and conducted 2285.5 m of MWD logs from pilot holes. and allows the identiication of critical intervals for special Expedition 315 (Megasplay Riser Pilot) penetrated 1287 m handling. In addition, the use of XCT imaging ing to construct and recovered 808 m of core. Expedition 316 (Megasplay and pseudo-density logs (using the “CT number” which is a Frontal Thrusts) penetrated 2103 m and recovered 1340 m of semi-quantitative proxy for bulk density), to measure faults core. Total drilling length was approximately 12,800 m,, and and fractures, and to identify unconformities and ine-scale total attempted coring was about 3400 m with an average details provided exciting results on board and opened a new core recovery rate of about 65�. All cores have been archived avenue for extensive post-expedition research.. for preservation, future description, and sampling at the Kochi Core Center (KCC), one of the three IODP core While shipboard and shore-based scientists from the repositories. NanTroSEIZE Stage 1 expeditions have already begun analyzing the huge volume of data taken from LWD and core During the course of these expeditions, Chikyu was able measurements, studies for future deep riser drilling,, in terms to test and reine operational techniques and structures that of geomechanical modeling and borehole stability,, are are well-established components of the ODP/IODP underway in CDEX in collaboration with industry and operational paradigm, but that are still relatively untested on research specialists. this newest platform for scientiic ocean drilling. These include severe, real-world tests of the Dynamic Positioning An immense amount of work has been required to prepare system,, drilling, coring, and laboratory systems, expedition the Chikyu for IODP science operations. While it is clear that management, safety monitoring, and onboard operational there is a lot of further effort required to develop the fullest safety and communications infrastructure. In addition, potential of the vessel and its laboratories, when we take into Chikyu was able to pioneer the use of new tools and equipment, account the successes, problems, and challenges experienced including the scientiic use of never-before-used LWD tools, during NanTroSEIZE Stage 1, the results of these three testing of new coring systems and techniques, testing of new Scientific Drilling, No. 6, July 2008 41 Progress Reports expeditions give us great conidence in the future of IODP operations using the Chikyu. " # 1922 $ 1753 % Figure 6. Usage and results from the X-ray computed tomography analyses. [A] Selected X-ray CT images. [B] The relationships that can be seen between the core photos and the CT images; Yellow and blue arrows indicate the position of the clear discontinuity seen in both core and CT image, with bright areas corresponding to mineralized material. The red line in the along-core CT image shows the position of the slice in the upper right. Spatial and angular relationships can be determined with high precision using core orientation. [C] X-ray CT imagery can be used to evaluate coring induced or drilling induced deformation or disruption of the core sample. This image shows flow-in of fluidized mud that occurred during core recovery of a piston core. [D] False color imagery based on CT-number (density contrasts related to pore spaces, water content, and mineral chemistry) can be used to highlight structural features such as this set of normal faults (cutting the core from top right to bottom left in this image). In all cases, cores are 2.5 inches across. Acknowledgements We would like to thank the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) for funding Chikyu, and to the host of staff, technical workers, managers, and operations personnel in all the various departments and agencies at JAMSTEC, at CDEX, at TAMU, at the ESO, and within the global science community for the work, advice, efforts, and support required to begin this scientiic endeavor with such success. Great thanks are owed to the crew of the Chikyu, the drilling crew and operational teams, the helicopter pilots, shorebased support staff and supply vessel crews, the technical and design teams who helped construct and test the vessel prior to IODP operations, to the science parties and laboratory staff, and to the enormous number of technicians, scientists, designers, programmers, and engineers who have contributed so much of their time, expertise, and advice to the preparation and execution of the irst successful IODP operations of the Chikyu. References Kimura, G., Tobin, H., and the NanTroSEIZE working group, 2003. NanTroSEIZE: The Nankai Trough Seismogenic Zone Experiment Complex Drilling Project. IODP-603 CDP3, revised proposal received 1 October 2003. 4 Scientific Drilling, No. 6, July 2008 Kinoshita, M., Brown, K., Saffer, D., Henry, P., Chester, F., Goto, T., Gulick, S., Hirono, T., Ito, H., Kato, A., Kimura, G., Kopf, A., Moore, G., Moore, J.C., Nakamura, Y., Park, J.-O., Saito, S., Schwartz, S., Shinohara, M., Stephen, R., Tobin, H., Ujiie, K., Tsunogai, U., and Yamano, M., 2003. NanTroSEIZE Drilling and Observatory Phase 2. Mechanical and Hydrologic State of Mega-Splay Faults: Implications for Seismogenic Faulting and Tsunami Generation, IODP 603BFull 2, revised proposal received October 2003. Moore, G.F., Bangs, N.L., Taira, A., Kuramoto S., Pangborn, E., and Tobin H., 2007. Three-dimensional splay fault geometry and implications for Tsunami generation. Science., 318(5853):1128–1131, doi:10.1126/science.1147195 Screaton, E., Underwood, M., Saffer, D., Wang, K., Wheat, G., Obana, K., Moore, G., Brown, K., and Ashi, J., 2005. The Nankai Trough Seismogenic Zone Experiment: Observatory Science at the Reference Sites. IODP 603D-Full2, revised proposal received April 2005. Suyehiro, K., Tobin, H., Araki, E., Bilek, S., Goto, T., Henry, P., Kimura, G., Kato, A., Kinoshita, M., Marone, C., Moore, G., Moore, J. C., Saffer, D., Sakaguchi, A., Shinohara, M., Stephen, R., Tsutsumi, A., Ujiie, K., and Wang, K., 2003. NanTroSEIZE Drilling and Observatory Phase 3: A Window into the Seismogenic Zone. IODP 603C-Full, revised proposal received October 2003. Tobin, H.J., and Kinoshita, M., 2006. Investigations of seismogenesis at the Nankai Trough,Japan. IODP Sci. Prosp., NanTroSEIZE Stage 1. doi:10.2204/iodp.sp.nantroseize1.2006. Available online at http://publications.iodp. org/scientiic_prospectus/NanTroSEIZE_stage1/. Underwood, M., Ashi, J., Soh, W., Morgan, J., Saito, S., Saffer, D., Screaton, E., Kinoshita, M., Moore, G., Kastner, M., Bilek, S., and Ujiie, K., 2003. NanTroSEIZE Reference Sites: Sampling and Measuring Inputs to the Seismogenic Zone, IODP 603A-Full2, revised proposal received April 2003. Authors Shin’ichi Kuramoto, Daniel Curewitz, Moe Kyaw Thu, Hideki Masago, JAMSTEC, Yokohama Institute of Earth Sciences, 3173-25 Showamachi, Kanazawa, Yokohama 2360001 Japan, e-mail: s.kuramoto@jamstec.go.jp� daniel@jamstec.go.jp� moe@jamstec.go.jp� masagoh@jamstec.go.jp. and the Exp. 314, 315, and 316 Science Parties Related Web Link http://www.iodp.org/scientiic-publications/ Figure and Photo Credits All photos courtesy of IODP and CDEX. Progress Reports Estimation of Minimum Principal Stress from an Extended Leak-off Test Onboard the Chikyu Drilling Vessel and Suggestions for Future Test Procedures by Weiren Lin, Koji Yamamoto, Hisao Ito, Hideki Masago, and Yoshihisa Kawamura doi:10.04/iodp.sd.6.06.008 Introduction To understand the physics of faulting and rupture propagation for the great M8-class Nankai earthquakes that recur approximately every 100 years, a comprehensive drilling project is underway: the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE� Tobin and Kinoshita, 2007),, which is part of the Integrated Ocean Drilling Program (IODP). Stress levels along seismogenic eismogenic ismogenic faults must be known in order to understand processes controlling the timing, energetics,, and extent of earthquake ruptures. For scientiic drilling projects such as NanTroSEIZE,, it is very important to determine the in situ stress state at the decollement and the mega splay fault in the Nankai Trough. Preliminary experiments to determine the orientations and magnitudes of principal stresses in the Nankai Trough were undertaken during the NanTroSEIZE Stage 1 expeditions using borehole image analysis (stress-induced breakouts and tensile fractures� Kinoshita et al., 2008) and indirect, core-based methods such as anelastic strain recovery (ASR� Lin et al. 2006). These experiments will provide necessary and important information about in situ stress. However, to improve reliability and reduce experimental uncertainties in these stress determinations, it is necessary to have direct in situ measurements of stress magnitudes—in particular,, the minimum principal stress— at depth. These direct measurements are best obtained using methods involving the initiation and propagation of hydraulic fractures at depth, such as the traditional hydraulic fracturing test, a leak-off test (LOT), or an extended leak-off test (XLOT, sometimes ELOT) (Zoback et al., 2003). In the present paper, we aim to show that Pressure and Valve flow meter with the advent Fluid Cementing Blow-out tank preventer pump Rig floor of the riser drilling vessel Chikyu, the XLOT is Casing pipe applicable and effective in deep scientiic ocean Cement drilling projects. Created Drill pipe fracture Open hole (e .g, 3 m -length) Figure 1. Schematic borehole configuration during a leak-off test (LOT) or extended leakoff test (XLOT; after Yamamoto, 2003) During previous ODP expeditions and non-riser IODP expeditions, LOT or XLOT (which are sometimes used to determine drilling parameters such as optimal mud density) have not been conducted because the borehole was open to the sealoor. Thus, it has been impossible to pressurize a short interval of open hole below the casing as needed to conduct a LOT or XLOT (see below) without utilizing time-consuming and frequently unreliable drill-pipe-deployed packers. In contrast, the new drilling vessel Chikyu provides a riser-drilling capability that allows pressuring the entire casing string with drilling mud immediately after the casing is cemented in place. Therefore, NanTroSEIZE Stage 2 will present the irst opportunity for a scientiic ocean drilling program to use LOT or XLOT procedures without using a packer, providing direct information on the in situ magnitude of the minimum principal stress at minimal cost and risk. In this study we will demonstrate the feasibility of using LOT and XLOT data acquired during the new riser-drilling program to determine stress magnitude. We will irst describe LOT and XLOT procedures, and then use an XLOT data set that was acquired during the 2006 Shimokita shakedown cruise of the Chikyu drilling vessel to estimate the magnitude of minimum principal stress. We then recommend what we believe to be the optimum procedures for implementation of LOT–XLOT for determination of stress magnitude during future Chikyu riser-drilling programs. Description of the Tests A LOT is a pumping pressure test carried out immediately below newly set casing in a borehole (Fig. 1). It is similar to other pumping pressure tests known as the pressure integrity test, formation integrity test, or casing-shoe integrity test. Each of these tests has a different target pumping pressure. The LOT technique was originally developed in the oil industry to assess the “fracture gradient” of the formation (i.e., the maximum borehole pressure that can be applied without mud loss) and to determine optimal drilling parameters such as mud density (Kunze and Steiger, 1991). The LOT procedures are relatively simple. An XLOT is a more complex test with extended pressurizing procedures, as described in detail below. In future riser-drilling by Chikyu, it may be possible to regularly implement LOT or XLOT at each casing shoe immediately after casing has been run and cemented. Scientific Drilling, No. 6, July 2008 4 Progress Reports bore hole ping mud into Pum Pumping pressure Formation Breakdown Pressure (FBP) Residual tensile strength component Instantaneous Shut-In Pressure (ISIP)=initial pressure decline after Pumping ceases pump turned off Fracture Propagation Leak-Off Pressure (LOP) Pressure (FPP) Formation Integrity Test (FIT) Second shut-in pressure Fracture propagation Fracture Closure Pressure (FCP)= picked using a double tangent 1st cycle Bleed-off Fracture Re-opening Pressure (Pr)=re-opening of fractures therefore no tensile strength or stress perturbation components 2nd cycle Time (Volume of mud pumped in borehole) Figure 2. Idealized relationship between pumping pressure and time or volume of injected fluid during an XLOT (after White et al., 2002). LOT and, in particular, XLOT procedures have been successfully and widely used to estimate the magnitude of minimum in situ horizontal stress (Addis et al., 1998� White et al., 2002� Yamamoto, 2003), mainly for the practical purpose of determining borehole stability during drilling operations. These data can be used for another important application—that is, to obtain in situ stress information that can be used in scientiic objectives. In a similar case in which high borehole temperatures precluded use of a packer Hickman et al. (1998) conducted this kind of test to obtain in situ stress magnitude. To carry out LOT or XLOT after setting casing and cementing, a short length (several meters) of extra open hole is drilled below the casing shoe. The casing shoe is then pressurized by drilling luid delivered through drill pipe from a cementing pump set on the rig loor of the drilling vessel. The pressure at the casing shoe is equal to the sum of the hydrostatic pressure of the drilling luid column and the ship-board pumping pressure. Figure ure 2 shows an idealized pumping pressure curve for XLOT (White et al., 2002). Initially, pumping luid into the borehole results in volumetric compression of the drilling mud column and elastic expansion of the casing string plus rock around the borehole. As the pressure in the borehole increases, the leak-off pressure (LOP) is reached when the relationship between pressure increase and volume of luid pumped deviates from linear. This occurs when luid begins to diffuse into the formation at a more rapid rate as the rock begins to dilate (Fig. 2). Generally, a LOT is a test that inishes immediately after LOP is reached. An XLOT is an extended version of a LOT, but it is also similar to the hydraulic fracturing test used for stress measurement. During an XLOT, pumping continues beyond the LOP point until the pressure peaks at formation breakdown pressure (FBP). This creates a new fracture in the borehole wall. Pumping is then continued for a few more minutes, or until several hundred liters of luid have ve been injected, to ensure stable fracture propagation into the undisturbed rock formation. The pumping pressure then stabilizes to an approximately constant level, which is called the fracture propagation pressure (FPP). Pumping then 44 Scientific Drilling, No. 6, July 2008 ceases (known as “shut-in”). The instantaneous shut-in pressure (ISIP) is deined as the point where the steep pressure decreasess after shut-in -in in deviates from a straight line. From our perspective, the most important pressure parameter is the fracture closure pressure (FCP), which occurs when the newly created fractures closes again. FCP is determined by the intersection of two tangents to the pressure versus mud volume curve (Fig. 2). The value of FCP represents the minimum principal stress (Yamamoto, 2003), because the stress in the formation and the pressure of luid that remains in the fractures have reached a state of mechanical equilibrium. White et al. (2002) collected high-quality XLOT data and showed that both FCP and ISIP provide better estimates of minimum principal stress than LOP, although the difference in the values of LOP and ISIP was small in their study. In addition, ISIP is visually easier to determine than FCP. To end the test, the valve in rig loor is opened,, and some of the luid in the borehole lows back into the luid tank (known as “bleed-off”). To conirm the pressure values obtained from the initial XLOT, a second pressurization cycle is warranted (Fig. 2). Because a fracture has been created by the irst execution of XLOT, in the second cycle the pressure at the time of re-opening of the fracture corresponds approximately to the FPP of the irst cycle. In general, it is advisable to conduct additional pressurization cycles beyond the second cycle in order to conirm that stable values of FCP and ISIP have been obtained. An Extended Leak-off Onboard the Chikyu During the Shimokita shakedown cruise (6 August to 26 October 2006), an XLOT was conducted onboard the Chikyu. The test was carried out at a depth of 525 meters below sealoor (mbsf) in 1180 m water depth� luid density (seawater) was 1.030 g·cm -3 , and the injection low rate was 0.5 bbl·min -1 (about 80 L·min ·min -1). Pressure and low rate were recorded at the surface, using a sample rate of 5 min -1. The resolution of the pressure measurements was 1 psi (about 7kPa) its accuracy is less than ±37 psi (about ±259 kPa). Because the main objectives of the irst drilling operation test of the Chikyu during the Shimokita shakedown cruise were re conirming basic drilling procedures, pure sea water was used,, and rough measurement conditions were adopted for the preliminary XLOT. At the Shimokita site, core samples were retrieved only to a depth of 365 mbsf. However, the lithology at the XLOT depth was identiied from cuttings analysis as volcanic tuff. The luid pumping rate was constant, and pumping was stopped immediately after formation breakdown (Fig. 3). About 400 liters iters (2.5 bbl) of seawater was injected into a length of about 3 m of uncased borehole for about 6 min, thus creating a fracture in the borehole wall. After shut-in, pressure was monitored for about 14 min and then released (bleed-off). -off). off). Although lthough two cycles were tried,, only nly a data set of the irst cycle was successfully obtained in this test. The he processes of formation breakdown and stable fracture propagation were not clearly evident in this test (compare Figs. 2 and 3). Moreover, the pressure versus time curve was not smooth, owing to the large data sampling interval during the pumping and monitoring processes and the relatively poor accuracy of the rig-loor pressure recorders. Thus, it was hard to pick the FCP with any conidence, as this requires that two tangents be drawn to the pressure decay curve. Instead, we estimate that the magnitude of the minimum principal stress lies between the pressure at the moment the pumps were turned off, which should be a close upper bound to the ISIP since we are conducting the test with low-viscosity sea water, and our estimated value for the FCP, obtained as best we could using a bi-linear tangent approach (Fig. 3). In this manner, we estimate that the magnitude of the minimum principle stress is 18.3–18.5 MPa. For comparison, we estimated the magnitude of vertical stress at the test depth from the density of the formation. An average formation density of 1.5 g·cm -3 from 0 mbsf to 365 mbsf was determined from the density proile of core samples retrieved during the Shimokita cruise. We assumed that the average density for the interval 365–525 mbsf was 1.8 g·cm -3� therefore, herefore, the vertical stress was estimated to be approximately 20 MPa. Thus, the magnitudes of the minimum principal stress from the XLOT and the vertical stresses are close to one another, suggesting that we either measured the vertical stress with the XLOT or that we measured the minimum horizontal stress and are in a transitional strike-slip to reverse faulting environment. Since we were not able to determine the attitude of the hydraulic fracture in the test interval, we cannot ascertain which of these two possibilities is correct. Considering the many past applications of XLOT, both in continental scientiic drilling projects and in industry oil ields (Kunze and Steiger, 1991� Lund and Zoback, 1999), we suggest that, although it is not a perfect and universally used technique, XLOT can provide data that are both valuable and practical for estimating the magnitude of minimum principal stress (Nelson et al., 2007). (equivalent to the previously mentioned casing-shoe integrity test) uses a lower maximum injection pressure than the predicted LOP and is designed to estimate the permeability of the formation, determine whether there are pre-existing fracture(s) and weakness(s), and check the effectiveness of cementing. The second cycle is a standard XLOT procedure, and the third cycle is a repetition of the second cycle to conirm the diagnostic pressure values obtained from the previous XLOT. It is also important to record a high accuracy, closely sampled data set to avoid some of the dificulties in accurately picking test parameters, discussed in the example presented above. Data monitoring and recording details should include pumping pressure, the volume of luid injected, and the volume of luid returned to the luid tank during bleed-off. We think this recording is quite easy. It is also important that the density of the luid being injected is well known so that the hydrostatic pressure at the casing shoe under in situ pressure and temperature conditions can be calculated� alternatively, down-hole pressure recording at the casing shoe can be employed (using a wireline or memory tool ) to measure directly pressure at the casing shoe. The procedures that we suggest (Fig. 4) and describe in detail below are similar to those conducted in deep onshore wells (Yamamoto, 2003). (1) In the irst (LOT) cycle, drilling luid is pumped into the borehole at a constant low rate (e.g., 0.5 bbl·min -11, or about 80 L·min ·min -1)� pumping stops before the expected LOP, and the well is shut-in for 5–10 min. The pressure decline during the very early stage of shut-in relects the decay of viscous pressure losses in the surface plumbing and drill pipe, and the pressure change during the later stage of shut-in is controlled by the permeability of the formation. If the pressure decline in the late stage of shut-in is large and does not stabilize, the leak-off of luid might be attributed to the existence of natural fractures or to ineffective cementing. If the casing shoe is too permeable, then the 1.4 XLOT Procedures for Stress Estimation Pump pressure (MPa) The XLOT procedure that we suggest for determination of stress magnitudes during future riser-drilling programs conducted onboard Chikyu is shown in Fig. 4. This procedure has several advantages over the types of tests often conducted following borehole completion. First, the XLOT procedure is superior to the LOT procedure. It can be dificult to obtain reliable estimates of minimum principal stress by using only the value of LOP, which is the only stress-related parameter obtained by the LOT procedure. Second, we suggest that implementation of multiple XLOT cycles (at least 3 cycles) will provide more reliable results than the LOT or XLOT procedure alone. The irst cycle Bleed-off 1.2 LOP 1 FCP 0.8 0.6 Shut-in (Stop pump) 0.4 0.2 0 -0.2 0 5 10 15 Time (min) 20 25 Figure 3. Pumping pressure at drilling rig level versus elapsed time during XLOT carried out on board the riser vessel Chikyu. Scientific Drilling, No. 6, July 2008 45 Progress Reports 2nd cycle Shut-in Break down Shut-in Bleed off Bleed off Pressure those of the irst cycle will show whether or not borehole integrity has been compromised. 3rd cycle Shut-in Bleed off Re-open Leak off Start pumping Start pumping Start pumping Time Figure 4. Suggested procedures for conducting XLOT to determine the magnitude of the minimum principal stress. second and third test cycles are unnecessary,, as a reliable measure of the minimum principal stress will not be possible. (2) In the second injection cycle, pumping continues for at least 1 min beyond formation breakdown, and the well is then shut-in. If formation breakdown is not achieved but pressure decreases during pumping (indicating fracture propagation, perhaps from a pre-existing fracture), then pumping should continue until the volume of luid injected reaches at least several barrels (e.g., 3 bbl, or about 450 L)) and the well is shut in. (3) The well then remains shut-in while pressure is monitored for at least 10 min or until the pressure ceases to decay. The well is then bled off. (4) To evaluate the pressure versus volume curve during bleed-off, low-back volume is monitored with a low meter. The curve shown in Fig. 5 is an idealized relation between pumping pressure and volume, and it indicates the total amount of luid lost into the formation (or through other system leaks) during the test. Raane et al. (2006) also mentioned that pump-in/low-back test appears to give a robust estimate of the minimum principal stress. (5) The third cycle repeats steps 2–4 and allows comparison of the pressure parameters obtained during the second cycle. (6) Comparison of the pressure decline curves of the third and second cycles provides information about the state of the borehole. For example, if the pressure decline after shut-in during the third cycle is comparable to that observed in earlier cycles, then the cement bond has not been damaged,, and with the test interval permeability has not been signiicantly affected. (7) If required, a fourth cycle of pumping can be undertaken to investigate borehole integrity, including the extent of formation permeability during the test. In this case, the casing shoe is again pressurized to the maximum pressure of the irst cycle. The well is then shut in,, and the pressure and luid volume monitored. Comparison of the pressure build-up rate (pressure versus volume) during injection and the pressure decline after shut-in during this cycle with 46 Scientific Drilling, No. 6, July 2008 There may be concern that the new fracture created during the XLOT has affected casing-shoe integrity. In general, casing-shoe integrity is maintained if appropriate drilling luid (mud) has been used (Morita et al., 1997). Calculation of minimum principal stress by using LOT– XLOT data depends on the assumption that a new fracture is created in a plane perpendicular to the minimum principal stress by the pumping pressure and that pre-existing fracture(s), weakness(s), anisotropy, and heterogeneity of the formation have no signiicant inluences. Therefore, knowing with certainty the attitude of the new fracture produced is very helpful to determine direction of the minimum principal stress. For this purpose, Fullbore Formation Microimager (FMI) and/or Ultrasonic Borehole Image (UBI) logs or impression packer before and after the test can be conducted to acquire borehole images in cases of hydraulic fracturing which is conducted not at the borehole bottom (casing shoe). However, it should be dificult in case of an XLOT before the test because its test interval is too short to allow installing of FMI- or UBI-type logs. Additionally, in many cases the resolutions of FMI or UBI images are too low to see a hydraulic fracture. Also, given the low probability of success, it is hard to justify the expense and rig time for running a log to image a 1–3 m section of borehole. The minimum principal stress determinate by an XLOT is equivalent to minimum principal horizontal stress in normal and strike-slip faulting environments� and hydraulic fracture is induced in a vertical plane. In contrast, in reverse faulting environments the minimum principal stress is equivalent to vertical stress� the fracture is formed in a horizontal plane. In general, it is dificult to identify if the minimum principal stress is vertical or horizontal stress without knowing attitude of hydraulic fracture induced. Only in cases where the minimum principal stress from an XLOT is signiicantly lower in magnitude than the calculated vertical stress, can the minimum principal stress be identiied as the minimum horizontal stress. Break down Shut-in Leak off Pressure 1st cycle Bleed off Flow-back volume Volume Figure 5. Relationship bet ween pumping pressure and injected volume corresponding to the 2nd cycle in Fig. 4. A drawback of the XLOT procedure that we have recommended is that it cannot be used to determine the magnitude of maximum principal stress, which is also dificult to determine using the standard hydraulic fracturing test (Ito et al., 2007). The magnitude of the maximum principal stress in deep wells is best practically determined through an integrated analysis of borehole breakouts and tensile fractures from image logs, rock strength,, and the minimum principal horizontal stress from the XLOT, as discussed,, for example,, in Zoback et al. (2003). However this integrated analysis has several problems which should be solved in the near future, such as rock strength problem (Haimson and Chang, 2002) and the effect of luid compressibility and compliance of the test system (Raaen et al., 2006). In the near future, it is preferable and hopeful that more reliable and robust in situ stress measurements will be developed and applied onboard the Chikyu. Summary Investigation of in situ stress at depth is a necessary and important outcome of IODP drilling programs such as NanTroSEIZE. Fortunately, the availability of the new research vessel Chikyu means that LOT and XLOT procedures can be readily undertaken during future riser-drilling programs� these will yield important information about in situ stress magnitude as well as providing some of the data needed for drilling operations (e.g., borehole stability analysis). We used data from the 2006 Chikyu Shimokita shakedown cruise to demonstrate the feasibility of using XLOT data to determine the magnitude of the in situ minimum principal stress at depth. The procedures that we have recommended for the application of XLOT to determine stress magnitude during future riser-drilling programs of the Chikyu represent the most important outcome of this work. Acknowledgements We thank the Chikyu drilling operation team for allowing us to use XLOT data acquired by them during the Shimokita cruise. We gratefully acknowledge Stephen Hickman for his careful reviewing and many constructive comments which greatly improved d the manuscript. This work was partly supported by Grant-in-Aid for Scientiic Research (C: 19540453) of the Japan Society for the Promotion of Science. References Addis, M.A., Hanssen, T.H., Yassir, N., Willoughby, D.R., and Enever, J.,, 1998. A comparison omparison of leak-off test and extended leak-off test data for stress estimation,, SPE/ISRM 47235.. Proc roc. SPE/ ISRM Eurock 98, Volume 2, Trondheim, im, m, Norway,, 8–10 –10 10 July 1998, pp. 131–140. –140. 140.. Haimson, B.C., and Chang, C., 2002. True triaxial strength of the KTB amphibolite under borehole wall conditions and its use to estimate the maximum horizontal in situ stress.. J. Geophys. Res., 107(B10):2257, (B10):2257,, doi:10.1029/2001JB000647. Hickman, S., Zoback, M.D., and Benoit, R., 1998.. Tectonic controls on fault-zone permeability in a geothermal reservoir at Dixie Valley, Nevada.. In n Holt,, R.M., et al. (Eds.), Eds.), ds.),, Rock Mechanics in Petroleum Engineering, vol. 1, Richardson, Texas exas (Society Society of Petroleum Engineers), ),, 79–86. Ito, T., Omura, K., and Ito, H., 2007. BABHY – A new strategy of hydrofracturing for deep stress measurements.. Sci.. Drill.., Special Issue, 1:113–116. :113–116. 113–116. Kinoshita, M., Tobin, H., and Moe, T., 2008. Preliminary results esults from NanTroSEIZE IODP Expedition 314, LWD Transect across the Nankai Trough off Kumano. Japan. Geoscience Union Meeting 2008, Chiba, Japan, 25–30 May 2008, U054-004. Kunze, K.R.,, and Steiger, er, r, R.P.,, 1991. Extended leak-off -off off tests to measure in situ stress during drilling.. In Roegiers,, J.-C. (Ed.), Ed.), d.), .), ), Rock Mechanics as a Multidisciplinary Science. Rotterdam (Balkema) Balkema) 35–44. Lin, W., Kwasniewski, M.,, Imamura,, T.,, and Matsuki,, K.,, 2006.. Determination of three-dimensional in situ stresses from anelastic strain recovery measurement of cores at great depth.. Tectonophysics, 426:221–238, :221–238, 221–238,, doi: 10.1016/j. tecto.2006.02.019. Lund, B., and Zoback,, M.D., 1999. Orientation and magnitude of in situ stress to 6.5 km depth in the Baltic Shield.. Int. J. Rock Mech. Min. Sci., 36:169–190. :169–190. 169–190. Morita, N., Fuh, G.-F., .-F., -F., .,, and Boyd,, P.A.,, 1997. 7.. Safety of casing-shoe -shoe shoe test and casing-shoe -shoe shoe integrity after testing. SPE Drilling & Completion, 12:266–274. –274. 274.. Nelson, E.J., Chipperield, eld, ld, S.T., Hillis, R.R., Gilbert, J., McGowen, J., and Mildren, S.D., 2007. The relationship between closure pressures from luid injection tests and the minimum principal stress in strong rocks.. Int. J. Rock Mech. Min. Sci., 44:787–801. :787–801. 787–801. Raaen, A.M., Horsrud, P., Kjorhold, H., and Okland, D., 2006. Improved routine estimation of the minimum horizontal stress component from extended leak-off tests.. Int. J. Rock Mech. Min. Sci., 43:37–48. :37–48. 37–48. Tobin, H., and Kinoshita, M., 2007. The IODP Nankai Trough Seismogenic Zone Experiment, Sci.. Drill.., Special Issue, 1:39–41. :39–41. 39–41. White, A.J., Traugott,, M.O., and Swarbrick, R.E., 2002. The use of leak-off tests as means of predicting minimum in situ stress.. Pet.. Geosci.., 8:189–193. :189–193. 189–193. Yamamoto, K., 2003. Implementation of the extended leak-off test in deep wells in Japan.. In n Sugawara, K. et al. (Eds.), ds.), .),, Proceedings of the Third International Symposium on Rock Stress Rs,, Kumamoto ‘03 03, Rotterdam (Balkema), 225–229. Zoback, M.D., Barton, C.A., Brudy, M., Castillo, D.A., Finkbeiner, T., Grollimund, B.R., Moos, D.B., Peska, P., Ward,, C.D., and Wiprut, D.J., 2003. Determination of stress orientation and magnitude in deep wells.. Int. J. Rock Mech. Min. Sci., 40:1049–1076. :1049–1076. 1049–1076. Authors Weiren Lin, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku 783-8502, Japan, e-mail: lin@jamstec.go.jp Koji Yamamoto, Technology Research Center, Japan Oil, Gas and Metals National Corporation, Chiba, Japan Hisao Ito, Hideki Masago,, and Yoshihisa Kawamura Kawamura, Center for Deep Earth Exploration, Japan Agency for MarineEarth Science and Technology, Yokohama, Japan Scientific Drilling, No. 6, July 2008 47 Technical Developments Ultra-Deepwater Riserless Mud Circulation with Dual Gradient Drilling by Greg Myers doi:10.04/iodp.sd.6.07.008 Introduction Drilling deep holes in very deep water presents the offshore drilling community with major wellbore stability challenges that are typically mitigated through the circulation of dense drilling mud to prevent hole collapse and to remove drilling debris (“cuttings”). This is normally accomplished through the application of a riser system (Fig. 1)�� however,, riser lengths are presently limited to use in water depths of around 3047 m. In the scientiic ocean drilling realm, we have been very successful in drilling relatively shallow holes (<1500 m) in water depths greater than 3657 m, a range we call “hyper-deep”. Drilling in these extreme water depths requires the use of the “riserless” drilling technique (Fig. 1A) which is not constrained by the length limitations of a riser system (“riser”). The new riser-capable drilling vessel Chikyu has enabled the Integrated Ocean Drilling Program (IODP) to drill deep holes in water depths up to 2500 m. Scientiic tiic objectives in greater water depths with borehole penetrations deeper than 2000 m still remain a major challenge, because IODP does not have effective options for drilling in these environments. A technological solution to improve the drilling of deep holes in ultra-deep -deep deep water with riserless drilling equipment may now be emerging through a joint effort between IODP-Management International (IODP-MI) and the energy industry. The technology, known as Riserless Mud Recovery (RMR), has been developed and commercialized by the Norwegian irm, AGR Drilling Services (http://www.agr. com/). The RMR system allows for the drilling of the upper section of a borehole using the dual gradient drilling technique (Fig. 1B). The AGR system is presently operating in water depths up to 457 m. This article describes this emerging drilling technology and outlines joint efforts by IODP-MI and the energy industry to modify the system and deploy it in water depths up to 3657 m. Summation of Offshore ffshore Drilling Problem � �ell Control and Costs Whether a drill site is located in terrestrial or marine environments, several problems are common to rotary drilling operations. Drilling cuttings must be removed from the borehole, drilling luid density must be managed to keep the borehole open without fracturing the formation, circulation must be maintained even when drilling luid is lost to the formation,, and pressure must be contained if over-pressured strata or gas are encountered (Weddle and Schubert,, 2000). These problems are exacerbated for offshore wells due to hydrostatic pressure constraints, especially in the upper section of the borehole where the sedimentary overburden is reduced and/or increased pore pressures may be encountered (Fig.. 2). Figure 1. Dual gradient drilling (DGD) equipment may provide the technology needed to drill deep holes in deepwater. Riser drilling will still yield the deepest holes and riserless drilling will provide access to the deepest waters. Riserless [A] and riser [C] drilling configurations are depicted with a version of dual gradient drilling equipment provided by AGR Drilling services, named Riserless Mud Recovery (RMR) system [B]. 48 Scientific Drilling, No. 6, July 2008 The result of this dynamic is a narrowing of the drilling “window” between the formation pore pressure and formation fracture pressure (Smith et al., 1999). As water depth increases, the “window” between the pore pressure and fracture pressure becomes even narrower as a result of the increasing inluence of the weight of the luid column. Riserless drilling primarily uses seawater, rather than drilling mud, to manage the borehole because drilling mud cannot be recirculated. Seawater has a signiicantly lower density than drilling mud, thus the boreholes are more likely to collapse with increasing hole depth as the pore pressure exceeds the hydrostatic pressure exerted by the seawater. For deeper drilling, drilling mud with regulated density must be continuously circulated in order to keep the borehole from collapsing and to remove cuttings from the borehole. The widely accepted standard equipment to establish continuous circulation is a marine drilling riser, which provides a conduit for returning the mud and cuttings to the drill rig. Current riser depth capabilities, however, only extend to just over 3047 m and are extremely expensive. Scientiic ocean drilling and the energy industry have ultra-deepwater targets of interest beyond the reach of current risers. Figure 2. The pressure conditions within an offshore borehole are complex and must be precisely Research is underway to design risers managed to achieve the target depth. Carefully selected drilling fluids provide the pressure of even greater depth potential using a needed to resist the formation pore pressure thereby keeping the borehole open without applying too much pressure and fracturing the formation. This optimal pressure zone between formation combination of metallic and composite pore pressure and formation fracture pressure is known as the drilling “window”. When drilling materials. However, the stresses due to with seawater, the formation pore pressure overcomes the borehole fluid pressure leading to vibration of these long riser strings and borehole collapse. the well control problems associated with hydrostatic pressure of the mud contained within the “window” between the formation pore pose signiicant operational problems. The use of alternate pressure (Fig. Fig. 3, red line) and the formation fracture techniques, such as riserless mud recovery and dual pressure (blue line), thereby avoiding wellbore instability. gradient drilling, could therefore provide an attractive option for both IODP and industry to drill deep holes in deep water Riser drilling and dual gradient drilling provide different settings where current capabilities are either insuficient or options for controlling borehole conditions while drilling. not economic. The primary difference is the point where the hydrostatic head of the drilling mud begins accumulating. Another way Dual Gradient Drilling Application for IODP of visualizing dual gradient drilling is to imagine the drilling equipment positioned on the sealoor. In this scenario, the RMR provides a dual gradient drilling setup of the well, weight of the luid column from the sea surface down to the while capturing the drilling luid and returning it to the sealoor is eliminated, thereby providing a larger drilling drillship (Fig. 3). The term “dual gradient” implies two “window” between the formation pore pressure and hydrostatic gradients: 1) the seawater gradient that begins at formation fracture pressures, resulting in increased well the sea surface, and 2) the drilling mud gradient that begins bore pressure management. at the sealoor. Conventional drilling has only one pressure gradient for both seawater and mud that originates at the sea In addition to well control, the RMR system also helps surface (Schubert, et al., 1999). Because dual gradient reduce the costs associated with deepwater drilling. First, drilling has much less hydrostatic “head” associated with the system eliminates the “pump and dump” drilling the drilling mud in the borehole, drilling luids can be strategy, where mud that is sometimes utilized for well properly weighted, allowing drilling to be more easily control in riserless drilling is directly discharged to the Scientific Drilling, No. 6, July 2008 49 Technical Developments sealoor. Collecting and reusing drilling mud signiicantly reduces the amount of mud required to install an offshore well. Second, as the number of casing strings can be reduced, the upfront costs for this material can be signiicantly reduced. Thus, the RMR system offers a complementary solution to the capabilities of the Chikyu and the standard riserless capabilities of the JOIDES Resolution. Chikyu provides much deeper borehole penetration with blow-out prevention capabilities, but it has a limited water depth range. The current JOIDES Resolution provides hyper-deepwater capabilities but with limited borehole penetration. A drilling platform successfully equipped with RMR and dual gradient capabilities would ill in this technology gap in a cost-effective manner, allowing pursuit of deep drilling targets in water depths up to 3657 m. Figure 3. The dual gradient drilling approach establishes the drilling mud hydrostatic gradient at the seafloor which allows for the use of heavier drilling muds with an advantageous pressure increase with depth. The use of optimized drilling mud provides better well control and fewer casing points by keeping the drilling fluid within the drilling “window” for more depths within the borehole. AGR Drilling Services has been providing RMR dual gradient drilling equipment to the energy industry for a number of years. The system has been successfully utilized in gas ields in Sakhalin (Brown et al., 2007) and the Caspian Sea. The equipment is mobilized and installed on the drill rig in modular sea-freight containers. Returning the drilling mud back to the drill rig for conditioning and recirculation requires sealoor mud suction equipment (Figs. 4 and 5), sealoor mud pumps, and a mud return line extending from the sealoor equipment back to the drill rig.. In shallower water depths below 1524 m, this line can be a lexible, large-diameter -diameter diameter hose. Beyond 1524 m, the mud return line will be fashioned from steel pipe, such as a drill pipe. The mud return line is deployed down to the sealoor and then secured as the pipe exits the rig’s moon pool. A remotely operated vehicle (ROV) is utilized to provide visual inspection of the sealoor equipment setup. Following the equipment setup, the drill string is run to the sealoor,, and the hole is spudded. The ROV system is deployed continuously to monitor the mud recovery system during drilling. To investigate the feasibility of utilizing the RMR system on the JOIDES Resolution to 3657 m, a small team was formed by IODP-MI with members from the IODP United States Implementing Organization (USIO), AGR Drilling Services, and British Petroleum (BP). This team submitted afeasibility and planning proposal to DeepStar, an industry technology development consortium consisting of eight energy companies focused on advancing the technolo- 50 Scientific Drilling, No. 6, July 2008 gies to meet deepwater water and ultra-deepwater business needs. DeepStar provides a forum to execute deepwater technology development projects and leverage the inancial and technical resources of the deepwater industry (www.deepstar. org). The study, planned for completion by the end of 2008, will investigate the system requirements for several different well conigurations and water depths ranging from 1523 m to 3657 m, depths of interest to both the energy industry and the scientiic community. This study includes determining the feasibility studies of modifying the deepwater AGR Figure 4. The AGR riserless mud recovery subsea equipment consists of a mud suction module (see above) and seafloor mud pumps. The mud is collected in the mud suction module and returned to the drillship via the seafloor mud pumps (image: courtesy of John Thorogood). References Brown, J.D., Urvant, V.V., Thorogood, J.L., and Rolland, N.L., 2007. Deployment of a riserless mud recovery system offshore Sakhalin Island. Presentation 105212, SPE/IADC Drilling Conference and Exhibition, 20–22 February 2007, Amsterdam, The Netherlands. Larsen, H.C., and Kushiro, I., 1997. Report of the Conference on Cooperative Ocean Riser Drilling (CONCORD). 22–24 July 1997, Tokyo, Japan. http://www.odplegacy.org/PDF/ Admin/Long_Range/CONCORD.pdf. Myers, G., Winker, C., Dugan, B., Moore, C., M., Sawyer, D., Flemings, P., and Iturrino, G., 2007. Ursa Basin explorers shine new light on shallow water low. Offshore Engineer, September Figure 5. The AGR riserless mud recovery system deployed on an oil and gas exploration vessel. system to operate in up to 3657 m of water and a feasibility study to determine the suitability of the JOIDES Resolution to deploy the AGR RMR system. Should the feasibility study show that the RMR system can be deployed from the JOIDES Resolution, IODP-MI will work with the USIO, AGR,, and BP to secure funds for a Gulf of Mexico deployment within two years to test the system capabilities in actual ield operations. Conclusions and Applications 2007, pp. 88–93. Schubert, J.J., Seland, S., Johansen, T.J., and Juvkam-Wold, H.C., 1999. Greater kick tolerance and fewer casing strings make dual gradient drilling a winner. IADC Well Control Conference of the Americas, 25–26 August 1999, Houston, Texas. Smith, K.L., Gault, A.D., Witt, D.E., Peterman, C., Tangedahl, M., Weddle, C.E., Juvkam-Wold, H.C., and Schubert, J.J., 1999. Subsea mudlift drilling joint industry project achieving dual gradient drilling technology. World Oil, Deepwater Technology (supplement), August 1999. http://www.worldoil. com/ Ma ga z i ne/ M AG A Z I N E _ DE TA I L . asp?A R T_ I D =3539&MONTH_YEAR=Aug-1999. If RMR and dual gradient drilling prove feasible for use on the JOIDES Resolution, IODP will be in a much improved position to address drilling problems (Larsen Larsen and Kushiro, 1997)) that consistently plagued the successful completion of highly ranked programs such as achieving deep crustal and even upper mantle objectives. And, it could open new areas of study in drilling deeper targets in over-pressured regions by providing a continuous supply of weighted mud needed to suppress shallow water lows (Myers et al., 2007). The he modiied AGR Drilling Services system could be leased as needed and deployed from the JOIDES Resolution, Chikyu, or another suitable platform as required to meet the scientiic tiic objectives of a given project. Acknowledgements The concepts and ideas presented in this article represent the amalgamation of previous work and informal discussions with many engineers from industry and scientiic drilling circles. I wish to acknowledge all who have helped developed this concept on any level, in particular, Pierre Beynet and Warren Winters at BP, Tom Janecek of IODP-MI and Tom Williams helped turn these thoughts into an engineering initiative. Special thanks to Chris Haver and Jim Chitwood of the DeepStar consortium for hearing our proposal and seeing the value in symbiotic industry and scientiic engineering efforts. Weddle, C.E., and Schubert, J.J., 2000. Factors to consider in dual gradient well control. IADC Well Control Conference and Exhibition, 6–7 December 2000, Houston, Texas. Author Greg Myers, IODP-MI Engineering and Operations Manager, IODP-MI Headquarters, 815 Connecticut Avenue, NW, Suite 210, Washington, DC 20006 U.S.A., e-mail: gmyers@iodp.org. Related �eb Links http://www.agr.com/ http://www.deepstar.org Photo Credits s Figs. 4 and 5: courtesy of John Thorogood (Drilling Drilling Global Consultant LLP)) Scientific Drilling, No. 6, July 2008 51 Technical Developments Magnetic Susceptibility as a Tool for Investigating Igneous Rocks—Experience from IODP Expedition 304 by Roger oger C.. Searle doi:10.04/iodp.sd.6.08.008 Continuous measurements of magnetic susceptibility have been commonly used on Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) expeditions to study minor lithological variations (for example, those related to climatic cycles) in sedimentary rocks, but they have been less frequently used on igneous rocks, although important post-cruise studies have utilized zed ed them (e.g., Ildefonse and Pezard,, 2001). Here I report its use (and that of the closely related electrical conductivity) on IODP Expedition xpedition 304 to examine igneous crustal rocks. Expedition 304/305 targeted the Atlantis Massif, an oceanic core complex on the Mid-Atlantic Ridge, and recovered a suite of igneous rocks comprising mainly gabbros, troctolites, and some diabases (Blackman Blackman et al.,, 2006�� Ildefonse et al.,, 2006, 2007� IODP Expeditions 304 and 305 Scientists, 2005). Shipboard measurements (on D/V JOIDES Resolution) of physical properties were made to characterize lithological units and alteration products, to correlatee cored material with down-hole logging data, and to interpret broader-scale geophysical data. Shipboard Measurements Magnetic susceptibility, k, is a dimensionless measure of the degree to which material can be magnetized in an external magnetic ield: k = M/H where M is the magnetization induced in the material by an external ield of strength H. Magnetic susceptibility is sensitive to variations in the type and concentration of magnetic grains in rocks and is thus an indicator of compositional variations. After recovery, cores were allowed to come to approximately room temperature (22 °–25°C), then magnetic susceptibility (MS) and non-contacting electrical resistiFigure 1. View of part of the multi- vity (NCR) were sensor track on JOIDES Resolution following during Expedition 304, showing the MS measured and NCR sensors. standard IODP procedu- 5 Scientific Drilling, No. 6, July 2008 res on whole core in split liner in the multi-sensor track (Blum, Blum, 1997,, Fig.. 1). ).. MS was measured inductively at 2-cm -cm cm intervals down core, using a model MS2C Bartington susceptibility meter, which has an 8-cm loop and operates at 0.565 kHz with a ield intensity of 80 A/m (Bartington Bartington Instruments, 1995). ).. The instrument is constructed so that for a core of diameter 65 mm,, the recorded value is the absolute volume susceptibility. The diameter of the Expedition 304 cores was always smaller (~5.5–6.0 cm), so I report results in Instrument Units (IU), which under the conditions given above approximate to dimensionless Système International (SI) units × 10 -5 . Because measured susceptibility depends on sample volume, measurements on pieces shorter than ~8 cm will be underestimated� such samples were lagged in my interpretations. A further complication is that the Bartington MS2C sensor currently has a maximum range of 10 4 IU� all readings greater than this lose the most signiicant digit, so that the signal appears to fall discontinuously to a low value, or “wrap around”. As a result, intervals where k values appear to approach 10 4 IU and then fall rapidly should be examined and used with care. However, there is a potential solution to this as described below. NCR was measured every 2 cm down core using a noncontacting inductive instrument, purpose-built for the MST by Geotek Limited (http://www.geotek.co.uk/site/index. http://www.geotek.co.uk/site/index. php). ).. Instrument output (in volts) is approximately inversely proportional to resistivity� the precise relationship was determined at the start of Expedition 304 by measuring brine samples of known salinity, though data in the IODP database are in uncalibrated voltages. The instrument is rated to 0.14 Dry Sat urat ed 2. 3 hrs Sat . 4. 6 hrs Sat . 10. 5 hrs Sat . 23. 7 hrs Sat . 34. 3 hrs U1309D 57R1 pieces 6- 7, satur ation tests 0.12 Diff: 2.3 hr 4.6 hr 10.5 hr 23.7 hr 34.3 hr 0.1 NCR, V Introduction Mean SD 0.0026 0.0056 - 0.0008 0.0049 0.0007 0.0047 0.0017 0.0043 0.0037 0.0058 0.08 0.06 0.04 0.02 0 0 20 40 60 80 100 120 140 160 Dist a n ce d o w n sa mp le , cm Figure 2. Results of repeated measurements of NCR on U1309D 57R-1 pieces 6 and 7, following drying and then saturation with seawater for periods from 2.3 h to 34.3 h. measure resistivity in the range 0.1 to 10 ohm-meters. I obtained apparently useful measurements to >100 100 ohm-m, but these high values are poorly calibrated. It is often more useful and intuitive to consider the reciprocal of resistivity, which is conductivity, measured in siemen iemen per meter (S m -1), and values are presented ed as such here. Geotek estimates the spatial resolution of the NCR as approximately 2 cm down core (http://www.geotek.co.uk/site/scripts/module.php? webSubSectionID=31). My calibration showed, however, that the sensor has to be between 4 cm and 8 cm from the end of the sample before the full resistivity was measured. Thus,, resistivity measured on pieces shorter than ~10 cm will be overestimated, and, as with MS, these were lagged. seemed to be closely correlated, independent of lithology (Fig. 3). This strongly suggests that the same minerals are responsible for both the conductivity and susceptibility. A check of common minerals that exhibit high conductivity and high susceptibility produced the results shown in Table 1. Pyrrhotite, ilmenite,, and magnetite all have high mean susceptibility and potentially high con- Figure 4. Plots of conductivity (red) ductivity, and are and susceptibility (blue) against depth for sections U1309D 35R-1 to 36R-1 relatively common in (unit 88, oxide gabbros). [A], logged igneous rocks.. values; [B] susceptibility augmented by integral amounts (1 or 2) of 10,000 IU Pyrrhotite was rare to compensate for limited range of the in the rocks recovered installed susceptibility sensor. Note during Expedition the good correlation with conductivity following this correction. 304, and I suspect that magnetite is the dominant mineral, as either a primary component or one produced during serpentinization. zation. ation. The Origin of Conductivity and Susceptibility in Igneous Rocks Electrical conductivity in rocks occurs by one of two mechanisms: ionic conductivity (in in which the drift of ions through conducting pore-water carries the current)) and electronic conductivity (in in which electrons travel through conducting solid minerals). ).. Most Expedition 304 rocks have low porosity (<3�), but the connectivity of pore spaces is critical in determining ionic conductivity. Normally, resistivity was measured on the MST about 2 h after the core came on board (the delay being the time required for core curation), and in this time the core can lose a signiicant proportion of its pore water. I ran a test on two long pieces (U1309D-57R-1 Pieces 6 and 7) from Hole 1309D Unit 137 (olivine-bearing gabbro), which was very conductive. After storage on board for several days allowed ed them to dry out, the working and archive halves were put together and held in place by elastic bands, and then were measured dry and after saturation in seawater for periods from 2.3 3 h to 34.3 h. Little variation was seen, suggesting that ionic conductivity was not the dominant mechanism (Fig. 2). Similar results were obtained from several other sections with varying lithology. S m-1 Figure 3. Plot of susceptibilit y versus conductivity for all values of conductivity <5 S m -1 from Hole U1309D measured on Expedition 304. The strong correlation of conductivity and susceptibility offers a way of checking and perhaps correcting the wraparound of strong susceptibility signals. Figure 4aa shows measured susceptibility plotted alongside conductivity for sections U1309D 35R-1 to 36R-1 (unit 88, oxide gabbros). Some parts, particularly between 194 and 195 mbsf, correlate very well, while others do not. However, by adding 10,000 IU, or occasionally 20,000 IU, to the logged value, a much improved correlation is seen (Fig. 4b). b). ). While this manual correction can be applied in some places,, it is tedious, and the number of wrap-around can be ambiguous� clearly, there is need for a susceptibility meter with extended range. Results esults here suggest it should be increased to at least 30,000 IU and probably to 50,000 IU. Early in Expedition 304 electrical conductivity and magnetic susceptibility Applications During Expedition 304, MS sometimes showed ed variations that are not immediately apparent in on-board lithological Table 1. Common minerals with high electrical conductivity or magnetic susceptibility (Telford et al., 1990) Mineral Pyrrhotite Susceptibility mean, IU Susceptibility range, IU Conductivity mean, Sm -1 Conductivity range, Sm -1 1.5 0.006–1.6 104 20.0–1.5×10 Ilmenite 1.9 0.3–3.8 Magnetite 6.3 5.0×10 –5.7×10 Pyrite 0.0015 -6 5 -2 20.0×10 –1.0×10 3 -4 1.8×10 –2.0×10 3 5 3.3 Scientific Drilling, No. 6, July 2008 5 Technical Developments Acknowledgements Magnetic susceptibility, IU 0 5000 10,000 Depth, mbsf descriptions. For example, Figure 5 shows the susceptibility logged for U1309B Unit 62, which appears to be a fairly uniform oxide diabase (Blackman, 2006), but it exhibits variations from essentially zero to over 5,000 IU (approximately 0.05 SI) over distances of ~1m. This observation spawned the hypothesis that the variations might be related to low phenomena and perhaps grain size variations at the edges of the unit. On-board examination of photomicrographs suggested that the intervals with low susceptibility might be places where magnetite had been extensively altered to lower susceptibility ilmenite (R.. Frost, pers. comm., omm.,, 2004, 2007), and led to a program of post-cruise research, which has shown that the susceptibility actually correlates quite well with observed proportion of oxides in thin section. References Figure 5. Susceptibility versus depth fo r H ole U1309B Unit 62, logged as a uniform oxide diabase. Red: MS measurements made >8 cm from the ends of pieces, which are considered reliable. Gray: points measured <8 cm from the ends of pieces, which are probably underestimates of true susceptibility. #  Magnetic susceptibility (SI) Structure measurement ID Structure Alteration intensity Igneous lithology Lithologic unit Shipboard Studies Orientation Scaned Image DN Piece Number Following this early success in using MS to identify potential lithological variations, we instituted the practice of routinely including MS in the visual core description sheets (so-called “barrel plots”) produced on board (Fig.. 6). These have already proved valuable for re-surveying the Expedition 304/305 cores post-cruise (B.. John, pers. comm., omm., 2007), and for investigations of the formation mechanism of serpentine from olivine-rich livine-rich troctolites (R.. Frost, pers. comm., omm.,, 2007).  6#3
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NCTG  UNIT-62 : Oxide-diabase Pieces 1−11 Primary Mineralogy :   Olivine Plagioclase    Clinopyroxene  Oxides Groundmass Modal 1% Size 0.6 mm Shape anhedral Phenocrysts Modal 55% Size 0.5−1.5 mm Shape subhedral Modal 2% Size <8 mm Shape subhedral Modal 45% Size 0.8 mm Shape anhedral  SECONDARY MINERALOGY: The section consists of fresh diabase. Plagioclase laths are unaltered. Pyroxenes have been partially altered to actinonite. Chlorite is rare. A coarser patch at 53 cm contains both dark and pale green amphibole and white specs of clay.  STRUCTURE : No additional structrue other than that notes in the Structure measurement ID column. VEIN ALTERATION : No veins CLOSE-UP PHOTOGRRAPHS: 304-U1309B-19R3, 72−90 cm (wet) 304-U1309B-19R3, 72−90 cm (dry backside)  Bartington Instruments, 1995. Operation Manual for MS2 Magnetic Susceptibility System, Oxford, U.K. Blackman, D.K., Ildefonse, B., John, B.E., Ohara, Y., Miller, D.J., MacLeod, C.J., and Expedition 304/305 Scientists, 2006. Oceanic Core Complex Formation, Atlantis Massif: Expeditions 304 and 305 of the riserless drilling platform from and to Ponta Delgada, Azores (Portugal), Sites U1309– U1311, 17 November 2004–7 January 2005, and from and to Ponta Delgada, Azores (Portugal), Site U1309, 7 January–2 March 2005. Proc. IODP, 304/305, doi:10.2204/iodp. proc.304305.2006. Blum, P., 1997. Physical properties handbook: A guide to the shipboard measurement of physical properties of deep-sea cores. ODP Tech. Note, 26, doi:10.2973/odp.tn.26.1997. Ildefonse, B., and Pezard, P. A., 2001. Electrical properties of slowspreading ridge gabbros from ODP Site 735, Southwest. Indian Ridge. Tectonophysics, 330:69–92, doi:10.1016/ S0040-1951(00)00220-1. Ildefonse, B., Blackman, D., John, B.E., Ohara, Y., Miller, D.J., MacLeod, C.J., and IODP Expeditionss 304/305 Scientists, cientists,, 2006. IODP Expeditions 304 & 305 characterize haracterize the lithology, ithology, structure, tructure, and alteration lteration of an oceanic ceanic core ore complex. omplex.. Sci.. Drill.., 3:4–11. :4–11. 4–11. Ildefonse, B., Blackman, D., John, B.E., Ohara, Y., Miller, D.J., MacLeod, C.J., and IODP Expeditions 304/305 Science Party, 2007. Oceanic core ore complexes omplexes and crustal accretion at slow-spreading ridges.. Geology, 35(7):623–626, :623–626, 623–626, doi: 10.1130/G23531A.1. IODP Expeditions 304 and 305 Scientists, 2005. IODP Expeditions 304 and 305: Oceanic Core Complex Formation, Atlantis Massif.. Sci.. Drill.., 1(1):28–31, :28–31, 28–31, doi:10.2204/iodp. sd.1.05.2005. Telford, W.M., Geldart, L.P., and Sheriff, R.E., 1990. Applied Geophysics. Cambridge (Cambridge University Press). Modal 2−3% COMMENTS: Section 19R-003 consists of the continuation of Unit 62. Pieces 4−7 record very low magnetic susceptibility.  I am indebted to the help of the Expedition 304/305 shipboard scientists, ship’s crews,, and coring staff. Special thanks go to Physical Properties Marine Laboratory Specialist for Expedition 304, Heather Paul, who expertly guided this neophyte through the complexities of the on-board Physical Properties Laboratory. My participation in Expedition 304 was funded by the Natural Environment Research Council’s thematic programme UKIODP. Author Roger oger C.. Searl Searle, Department of Earth Sciences, Durham University, Durham, DH1 3LE, U.K., e-mail: r.c.searle@durham.ac.uk.  6OJU
    # 1I   # Figure 6. Visual core description (“barrel sheet”) for part of U1309B Unit 62 (9 6.92 – 98.26 mbsf) with additio n of susceptibilit y (red). 54 Scientific Drilling, No. 6, July 2008 Related �eb Links http://www.geotek.co.uk/site/index.php h t t p : // w w w. g e o t e k . c o . u k /s i t e /s c r i p t s /m o d u l e . php?webSubSectionID=31 Workshop Reports Marine Impacts and Environmental Consequences – Drilling of the Mjølnir Structure, the Barents Sea doi:10.04/iodp.sd.6.09.008 by �enning Dypvik, Philippe Claeys, Ale� Deutsch, Frank T. Kyte, Takafumi Matsui, and Morten Smelror Introduction In September 2007, thirty-three scientists attended an international workshop in Longyearbyen (Svalbard, Norway) to discuss impacts of extraterrestrial bodies into marine environment and to prepare for the drilling of the 142-Ma-old -Ma-old Ma-old -old old Mjølnir impact structure in the Barents Sea (Fig. 1� Gudlaugsson, 1993� Dypvik et al., 1996, Tsikalas et al., 1998). A ield trip visited the ejecta layer in the Janusfjellet Mountain in Isfjorden, just outside Longyearbyen (Fig. 2). The workshop focused on two topics: 1) mechanisms of marine impact cratering including ejecta formation and distribution, geothermal reactions, and the formation of tsunami, and 2) environmental effects of marine impacts. Both topics are highly relevant to the Mjølnir event and the geological evolution of the Arctic, as well as to the biological changes at the Jurassic-Cretaceous -Cretaceous Cretaceous boundary. Against this background were a) concrete drilling targets formulated, b) plans outlined for compiling data from existing geological and geophysical surveys as the basis for Integrated Ocean Drilling Program (IODP) and International Continental Scientiic Drilling Program (ICDP) drilling proposals, and c) a steering group and science teams established for compiling old and new material as a foundation for the development of drilling proposal. coring projects in the Chicxulub, Bosumtwi, and Chesapeake Bay impact structures were of great scientiic gain. One of the best preserved known impact craters on Earth is the Mjølnir impact structure. It was discovered by seismic data during petroleum exploration in the Barents Sea but never sampled by coring. An extensive geophysical database has been collected over the Barents Sea, and more than sixty petroleum exploration wells have been drilled, particularly along basin margins and on structural highs. In addition,, many shallow drill holes on sub-cropping sedimentary sequences have been drilled in the more central and remote areas of the Barents Sea. See also the Norwegian Petroleum Directorate (NPD� http://www.npd.no). The Mjølnir Structure is 40 km in diameter and is located at the Bjarmeland Platform in the central Barents Sea (Fig. 1), beneath 350 m of water. Its elevated central high (Fig. 3)) is Scientific Background Asteroid and comet impacts are now recognized as an important and regular geological process releasing vast amounts of energy and resulting in near instantaneous increase in temperature and pressure, structural deformation, and redistribution of target materials. It is presently accepted that impacts, especially those in a marine environment, have very important inluencess on the development of the Earth. However, detailed knowledge of the geological and physical aspects of the impact process itself, as well as its environmental and biological consequences, is still limited. This is mainly due to the fact that a large majority of the ~170 170 currently known impact craters on the Earth and their ejecta deposits are rather poorly preserved. Only twenty-ive of these craters represent marine impacts, and very few of those have remained submerged with a potential for preservation of the original structure (Dypvik and Jansa, 2003). No completely retained marine crater has been investigated in detail yet, while in the last years ICDP land Figure 1. A tectonic map of the Bjarmeland Platform area in the Barents Sea, with a regional inset showing the Mjølnir and Svalbard position. The Mjølnir impact crater location and key shallow drillholes are shown in the main map. Scientific Drilling, No. 6, July 2008 55 Workshop Reports covered by ~50 50 m of younger sediments. Geophysical, geological, and mineralogical data unequivocally substantiate the origin of the structure by an impact event into a sedimentary platform with 300–500 m paleo-water depth (e.g., Dypvik et al., 1996� Smelror et al., 2001� Sandbakken et al., 2005). The impact has been dated at about 142 Ma (Dypvik et al., 1996), very close to the Jurassic-Cretaceous boundary. At this time, the platform comprised upper Paleozoic strata, mainly carbonates and evaporates, overlain by 4–5 km of thick Mesozoic siliciclastic marine sediments (Dallmann, 1999). The �orkshop Program Figure 3. The seismic model of Mjølnir structure. The workshop included the following topics: (1) Review the science behind marine impacts and the Mjølnir project. The state of knowledge, and ongoing geological and geophysical investigations in the Arctic realm, the Barents Sea, and Mjølnir were outlined by specialists of Arctic geology and members of the Mjølnir research group. (2) Review of petroleum exploration drilling in the Barents Sea was presented by one representative from the NPD and representatives from Norsk Hydro and Statoil (now StatoilHydro). Drilling experts from ICDP, Drilling, Observation and Sampling of the Earths Continental Crust (DOSECC) and IODP presented different drilling options. (3) Scientiic goals and drilling strategies for the Mjølnir. A plenary session was followed by discussions in two break-out groups, whose recommendations are summarized below. (4) An excursion was organized to the site of possible Mjølnir ejecta at the mountain Janusfjellet in Isfjorden (Fig. 2). The �orkshop Outcome Deep wells in the Mjølnir impact structure would be of great interest to the international scientiic community, in order to study the shock propagation, collapse,, and re-sedimentation of the >6-km-thick 6-km-thick -km-thick km-thick sedimentary succession. Coring through this succession will make structural analysis and detailed understanding of crater generation and deformation possible and help constrain numerical modeling. However, the costs for deep coring in the harsh environments of the Barents Sea makes it Figure 2. The sun over Isfjorden and the ejecta locality at Janusfjellet. 56 Scientific Drilling, No. 6, July 2008 unrealistic to raise funding for such operations in the foreseeable future. One of the great scientiic advantages with the Mjølnir impact crater is the clear correlation between the crater and its very well preserved ejecta found in shallow drillings in the Barents Sea and on land (Svalbard and possibly Siberia� Dypvik et al., 2004� 2006). During a large part of late Jurassic and early Cretaceous, the Barents Sea region formed an epicontinental sea dominated by anoxic sedimentation of black, organic-rich -rich rich clays. The Mjølnir bolide impacted into these sediments,, and the crater and portions of the ejecta localities were buried and have remained buried under sediments and water since its formation. Those ejecta localities are well-preserved -preserved preserved and accessible by shallow drilling (e.g.,, Bugge et al., 2002). It is one of the few places on the Earth where such important relations can be studied in detail. This is clearly of great importance for understanding the crater and ejecta formation, including the study the environmental consequences of marine impacts (Dypvik et al., 2006� Smelror et al., 2002). We will use Mjølnir as a type locality to study ejecta generation and distribution and possible relationships between the impact and biotic evolution. Mjølnir ejecta may even serve as a Boreal-Tethyan stratigraphic marker and could be useful in correlation of these two distinct provinces near the poorly understood Jurassic-Cretaceous -Cretaceous Cretaceous boundary (Smelror et al., 2001�� 2002). Further research could greatly expand our initial knowledge on tsunami generation and formation, impact ignitions of hydrocarbons in the target area, ires and subsequent soot precipitation. Calculations show that organic matter equivalent to a year’s oil production of one Norwegian Shelf giant ield (about thirty million std. m3 oil in place) was burned during the irst twenty minutes of the Mjølnir event (Dypvik et al., 2008). ). The development of the Mjølnir research program should be carried out in full cooperation with the NPD and in close contact with the oil industry active in the region (e.g.,, StatoilHydro, ENI), making use of their extensive geophysical database and deep wells. A two-step -step step drilling project was recommended: Step 1. Drilling of ive to six,, up to 300-m-deep -m-deep m-deep -deep deep core holes in 350–400 m water depth around the Mjølnir structure to map and understand ejecta formation and distribution, coupled with in situ disturbance of sediments due to seismic and shock waves, or erosion by displaced water near the crater. Analysis of the cored material will be accompanied by sophisticated simulation models (Shuvalov and Dypvik, 2004) of the formation and deposition of ejecta in a marine environment. Step 2. Drilling of one or two deep holes within the central moat to understand the inner structure of a large crater. At this point, however, the cost of such a project possibly requiring riser drilling is dificult to assess. Future Plans An international steering group (the authors of this paper) was established and charged with producing a draft project proposed by the end of 2008. The steering group will also be responsible for compiling the inal drilling proposals to IODP, ICDP,, and the Norwegian Research Council (NFR) by spring 2009. For further information on the Mjølnir drilling project, please contact the authors or visit http://mjoelnir. icdp-online.org/. Acknowledgements The workshop was kindly supported by ICDP, ESF-The Magellan Program, Statoil, Norsk Hydro, University Center on Svalbard,, and University of Oslo. References Bugge, T., Elvebakk, G., Fanavoll, S., Mangerud, G., Smelror, M., Weiss, H.M., Gjelberg, J., Kristensen, S.E., and Nilsen, K., 2002. Shallow stratigraphic drilling applied in hydrocarbon exploration of the Nordkapp Basin, Barents Sea. Mar. Pet. Geol., 19:13–37, doi: 10.1016/S0264-8172(01)00051-4. Dallmann, W.K., 1999. Lithostratigraphic Lexicon of Svalbard. Tromsø, Norway (Norwegian Polar Institute), 318 pp. Dypvik, H. and Jansa, L., 2003. Sedimentary signatures and processes during marine bolide impacts: a review. Sed. Geol., 161:309–337, doi: 10.1016/S0037-0738(03)00135-0. Dypvik, H., Gudlaugsson, S.T., Tsikalas, F., Attrep, M., Jr., Ferrell, R.E., Jr, Krinsley, D.H., Mørk, A., Faleide, J.-I., and Nagy, J., 1996. The Mjølnir structure – An impact crater in the Barents Sea. Geology, 24:779–782, doi:10.1130/00917613(1996)024<0779:MLSAIC>2.3.CO�2. Dypvik, H., Smelror, M., Sandbakken, P.T., Salvigsen, O.T., and Kalleson, E., 2006. Traces of the marine Mjølnir impact event. Palaeogeogr. Palaeoclimatol. Palaeoecol., 241: 621–634. Dypvik, H., Mørk, A., Smelror, M., Sandbakken, P.T., Tsikalas, F., Vigran, J.O., Bremer, G.M.A., Nagy, J., Gabrielsen, R.H., Faleide, J.I., Bahiru, G.M., and Weiss, H.M., 2004. Impact breccia and ejecta from the Mjølnir crater in the Barents Sea—The Ragnarok Formation and Sindre Bed. Nor. J. Geol., 84 (3), 143–167. Dypvik, H., Wolbach, W., Shuvalov, V., and Weaver, S., 2008. Did the Mjølnir asteroid impact ignite Barents Sea hydrocarbon source rocks? In Evans, K., Horton, J.W., Jr., King, D.T., Jr., and Morrow, J.R. (Eds.) The Sedimentary Record of Meteorite Impacts: Geological Society of America Special Paper, 437: 65–72, Boulder, Colo. (Geological Society of America) Gudlaugsson, S.T., 1993. Large impact crater in the Barents Sea. Geology, 21:291–294, doi:10.1130/0091-7613(1993)021<0291: LICITB>2.3.CO�2. Sandbakken, P.T., Lagenhorst, F., and Dypvik, H., 2005. Shock metamorphism of quartz at the submarine Mjølnir impact crater, Barents Sea. Meteor. Planet. Sci., 40:1363–1375. Shuvalov, V. and Dypvik, H., 2004. Ejecta formation and crater development of the Mjølnir impact. Met. Planet. Sci., 39(3):467–478. Smelror,, M., Dypvik,, H., and Mørk,, A., 2002. Phytoplankton blooms in the Jurassic-Cretaceous boundary beds of the Barents Sea possibly induced by the Mjølnir impact. In Buffetaut, E., and Koeberl, C. (Eds.), .), ), Geological and Biological Effects of Impact Events. Impact Studies, vol. 1, Heidelberg, (Springer), 69–81. Smelror,, M., Kelley,, S., Dypvik,, H., Mørk,, A., Nagy,, J., and Tsikalas,, F., 2001. Mjølnir (Barents Sea) meteorite impact ejecta offers a Boreal Jurassic-Cretaceous boundary marker. Newsletters in Stratigraphy, 38:129–140. :129–140. 129–140. Tsikalas,, F., Gudlaugsson,, S.T., and Faleide,, J.-I., 1998. The anatomy of a buried complex impact structure: the Mjølnir Structure, Barents Sea. J.. Geophys.. Res.., 103:30469–30483. Authors Philippe Claeys, Department artment tment ment of Geology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium, e-mail: phclaeys@vub.ac.be.. Alex Deutsch, Institut für Planetologie, Westfaelische Wilhelms-Universität Münster Wilhelm-Klemm-Str. 10, D48149 Münster, Germany. Henning Dypvik (coordinator), Department of Geosciences, University of Oslo, P.O. Box 1047, No 0316 Oslo, Norway. Frank T. Kyte, Institute of Geophysics and Planetary Physics, UCLA University of California, Los Angeles, Calif. 90095-1567, U.S.A. Takafumi Matsui Department of Complexity Science and Engineering, University of Tokyo, Tokyo, Japan.. Morten Smelror, Geological Survey of Norway, No 7491 Trondheim, Norway. Related �eb Links http://mjoelnir.icdp-online.org/ http://www.npd.no Photo Credits Figs. 1 and 3: Filippos Tsikalas, University of Oslo and ENI, Norway Fig. 2: P. Claeys, A. Deutsch. Scientific Drilling, No. 6, July 2008 57 Workshop Reports Drilling the North Anatolian Fault by Georg Dresen, Marco Bohnhoff, Mustafa Aktar,, and �aluk Eyidogan doi:10.04/iodp.sd.6.10.008 An international workshop entitled “GONAF: A deep Geophysical Observatory at the North Anatolian Fault”, was held 23–27 April 2007 in Istanbul,, Turkey. The aim of this workshop was to reine plans for a deep drilling project at the North Anatolian Fault Zone (NAFZ) in northwestern Turkey. The current drilling target is located in the Marmara Sea offshore the megacity of Istanbul in the direct vicinity of the main branch of the North Anatolian Fault on the Prince Islands (Figs. 1 and 2). The NAFZ represents a 1600-km-long -km-long km-long -long long plate boundary that slips at an average rate of 20–30 mm·yr-1 (McClusky et al., 2000). It has developed in the framework of the northward moving Arabian plate and the Hellenic subduction zone where the African lithosphere is subducting below the Aegean. Comparison of long-term slip rates with Holocene and GPS-derived slip rates indicate an increasing westward movement of the Anatolian plate with respect to stable Eurasia. During the twentieth th century, the NAFZ has ruptured over 900 km of its length. A series of large earthquakes starting in 1939 near Erzincan in Eastern Anatolia propagated westward towards the Istanbul-Marmara region in northwestern orthwestern western estern Turkey that today represents a seismic gap along a �100-km-long -km-long km-long segment below the Sea of Marmara. This segment did not rupture since 1766 and,, if locked,, may have accumulated a slip deicit of 4–5 m. It is believed being capable of generating two M�7.4 earthquakes within the next decades (Hubert-Ferrari et al., 2000)�� however, owever, it could even rupture in a large single event (Le Pichon et al., 1999). The most recent devastating earthquakes in the region occurred in 1999 near Izmit and Düzce with magnitudes >7. -1 -1 -1 -1 Figure 1. Google Earth view of the Marmara Sea / Istanbul region. Red lines indicate major segments of the North Anatolian Fault Zone (NAFZ). Stars indicate major events that occurred in the last 2000 years. 58 Scientific Drilling, No. 6, July 2008 Their western termination of rupture is located offshore below the eastern Sea of Marmara possibly extending to just south of the Princes Islands (Özalaybey et al., 2002) within ~20 km of Istanbul. Current seismic activity in the eastern Marmara Sea indicates a complex fault network at the transition between the western end of the Izmit earthquake rupture and the assumed seismic gap south of Istanbul. The majority of focal mechanism solutions indicate dominant strike-slip motion with minor normal faulting activity (Örgülü and Aktar, 2001� Karabulut et al., 2002). However, existing seismic observations lack the spatial and temporal resolution required to accurately distinguish between locked and creeping segments of the NAFZ. This is due to the threshold (magnitude >2) 2) of the existing seismic networks. The knowledge of the stress state at the NAFZ is rudimentary at best. Stress orientation (World Stress Map) with respect to the fault zone is mainly based on a small number of focal mechanisms of larger seismic events (Heidbach et al., 2004) and aftershocks (Bohnhoff et al., 2006). Maximum compressive stress is generally oriented at 35°–45° with respect to the fault trend and in agreement with predictions from Coulomb friction theory. In contrast to other major plate bounding faults,, the NAFZ does not appear to be a weak fault. However, no data exist on stress magnitudes and on heat low close to the NAFZ in the Marmara Sea region. The GONAF initiative focuses on the installation of a borehole observatory in a deep borehole at the NAFZ. This will conduct long-term monitoring of seismic activity, stress, heat and luid low. The target area is located offshore Istanbul in the Marmara Sea close to the main branch of the NAFZ on the outermost island of Sivriada (Fig. 2). The projected observatory is located at the transition between the western end of the 1999 Izmit rupture and the 150-km-long -km-long km-long -long long seismic gap along the western NAFZ that may have accumulated a 4–5 m slip deicit within the Figure 2. Proposed drilling location on the is- past 250 years. land of Sivriada that is located in direct vicinity to the main branch of the NAFZ. Presentations at the workshop included an overview of existing fault drilling projects, a session on seismotectonics, seismology,, and the geological setting of western part of the NAFZ and the Marmara Sea region, and deep borehole monitoring results and technology. The potential drill site on Sivriada island was visited during a one-day ield trip. A summary of suggested pre-site and drilling-phase studies concluded the workshop. Key scientiic and technical aspects of a deep drillhole and long-term geophysical observatory were discussed in order to prepare for a full drilling proposal to be submitted to the International Scientiic Continental Drilling Program (ICDP). Reports on fault mechanics and earthquake processes as well as technical and logistical challenges of a drilling presented included projects in California (San Andreas Fault Observatory at Depth� Hickman, et al., 2007), ), Taiwan (Taiwan Chelungpu-Fault Drilling Project� Ma and Tanaka,, 2007), ), Japan (Nojima Fault� Ito et al.,, 2003), ),, and Greece (Corinth Rift Laboratory� Cornet,, 2007). ). All fault drilling projects produced new and ground-breaking results with regards to physics of faulting, slip distribution at hypocentral depth, source mechanisms,, and the earthquake energy budget. Other presentations detailed the structure, kinematics,, and seismotectonics of the western NAFZ emphasizing recent and partly unpublished ield data. Unresolved fault structure and hypocenter locations in the Marmara Sea underscored the need for high-resolution long-term seismological observations and detailed wide-angle seismic proiling close to the planned drill site. A inal series of presentations focussed on state-of-the-art monitoring strategies for a borehole observatory including instrumentation and other technical aspects. In particular, detailed introductions presented new scientiic results and technical achievements covering high-resolution earthquake monitoring, strain monitoring, velocity measurements, stress measurements, heat and luid low measurements,, and borehole logging techniques. References Bohnhoff, M., Grosser, H., and Dresen, G., 2006. Strain partitioning and stress rotation at the North Anatolian fault zone from aftershock focal mechanisms of the 1999 Izmit Mw=7.4 earthquake. Geophys. J. Int., 160:373–385. Cornet, F.H., 2007. The Corinth Rift Laboratory or an in situ investigation on interactions between luids and active faults), Sci. Drill. Special Issue, 1:35–38. Heidbach, O., Barth, A., Connolly, P., Fuchs, F., Müller, B., Reinecker, J., Sperner, B., Tingay, M., and Wenzel, F., 2004. Stress maps in a minute: The 2004 world stress map release. Eos Trans., 85(49):521–529. Hickman, S., Zoback, M., Ellsworth, W., Boness, N., Malin, P., Roecker, S., and Thurber, C., 2007. Structure and properties of the San Andreas Fault in central California: Recent results from the SAFOD experiment. Sci. Drill. Special Issue, 1:29–32. Hubert-Ferrari, A., Barka, A., Jacques, E., Nalbant, S.S., Meyer, B., Armijo, R., Tapponnier, P., and King, G.C.P., 2000. Seismic hazard in the Marmara Sea region following the 17 August 1999 Izmit earthquake. Nature, 404:269–273, doi:10.1038/35005054. Karabulut, H., Bouin, M.-P., Bouchon, M., Dietrich, M., Cornou, C., and Aktar, M., 2002. The seismicity in the Eastern Marmara Sea after the 17 August 1999 Izmit Earthquake. Bull. Seismol. Soc. Am., 92(1):387–393, doi:10.1785/0120000820. Le Pichon, X., Şengör, A.M.C., and Taymaz, T., 1999. The Marmara fault and the future Istanbul earthquake. In Karaca, M., and Ural, D.N. (Eds.), ITU-IAHS International Conference on the Kocaeli earthquake 17 August 1999, Istanbul (Istanbul Technical University), 41–54. Ma, K.-F., and Tanaka, H.,2007. Drilling of the Chelungpu Fault after the 1999 Chi-Chi, Taiwan earthquake (Mw7.6): Understanding physics of faulting). Sci. Drill. Special Issue, 1:33–34. McClusky, S., Balassanian, S., Barka, A., Demir, C., Ergintav, S., Georgiev, I., Gurkan, O., Hamburger, M., Hust, K., Kahle, H., Kastens, K., Kekelidze, G., King, R., Kotzev, V., Lenk, O., Mahmoud, S., Mishin, A., Nadariya, M., Ouzounis, A., Paradissis, D., Peter, Y., Prilepin, M., Reilinger, R., Sanli, I., Seeger, H., Tealeb, A., Toksöz, M.N., and Veis, G., 2000. Global positioning system constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus. J. Geophys. Res., 105:5695–5719, doi:10.1029/1999 JB900351. Ito, H., Roeloffs, E., Matsumoto, N., Kuwahara, Y., 2003. Has the Nojima Faulthhealed Rapidly? – Results from seismogenic Zone Drilling and Monitoring at the Nojima Fault, Japan. European Geophysical Society, Geophys. Res. Abstr., Vol. 5, 06047. Örgülü, G., and Aktar, M., 2001. Regional Moment Tensor Inversion for Strong Aftershocks of the August 17, 1999 Izmit Earthquake (Mw=7.4). Geophys. Res. Lett., 28(2), 371–374, doi:10.1029/2000GL011991. Özalaybey, S., Ergin, M., Aktar, M., Tapirdamaz, D., Biçmen, F., and Yörük, A., 2002. The 1999 Izmit earthquake sequene in Turkey: seismological and tectonic aspects, Bull. Seismol. Soc. Am. 92: 376–386, doi:10.1785/0120000838. Authors Georg Dresen, GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473, Potsdam, Germany, e-mail: dre@ gfz-potsdam.de. Marco Bohnhoff, GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473, Potsdam, Germany. Mustafa Aktar, Bogazici University, Kandilli Observatory and Earthquake Research Institute (KOERI), Cangelkoy, Istanbul, 81220, Turkey. Haluk Eyidogan, Istanbul Technical University, Mining Faculty, Department of Geophysics, 34469, Maslak, Istanbul, Turkey. Related �eb Link http://www.gonaf.de/ Scientific Drilling, No. 6, July 2008 59 Workshop Reports Scientific Drilling of the Terrestrial Cretaceous Songliao Basin by Yongjian �uang, Chengshan �ang, and the Terrestrial Scientiic Drilling of the Cretaceous Songliao Basin Science Team doi:10.04/iodp.sd.6.11.00 Investigations of critical climate changes during the Cretaceous have the potential to enhance our understanding of modern global warming because the extreme variances are the best-known and most recent example of a greenhouse Earth (Bice et al., 2006). Marine Cretaceous climate archives are relatively well explored by scientiic ocean drilling programs such as the Integrated Ocean Drilling Program (IODP) and its predecessors. However, Cretaceous terrestrial climate records are at best fragmentary (Heimhofer et al., 2005). The long-lived Cretaceous Songliao Basin of NE China is an excellent candidate to ill this gap and provide important ocean-continent linkages in relation to environmental change (Fig. 1). This basin, located within one of the largest Cretaceous landmasses (Scotese, 1988), acted for about 100 million years as an intra-continental sediment trap� the present-day area of the basin is about 260,000 km 2 . It provides an almost complete terrestrial sedimentary record from the Upper Jurassic to the Paleocene (Chen and Chang, 1994). Large-scale geological and geophysical investigations of lacustrine sediments and basin structures demonstrate that a rich archive of Cretaceous paleoclimate proxies exists. For example, the basin includes the Jehol Biota, a terrestrial response to the Cretaceous oceanic anoxic events (OAEs), and a potential K/T boundary (Qiang et al., 1998). An ongoing drilling program is supported by the Ministry of Science and Technology of China and by the Daqing Oilield. It allowed for recovering of nearly complete cores from Upper Albian to the Uppermost Cretaceous in two boreholes (SK-I, SK II� commenced in 2006, Fig. 1). However, the older Cretaceous sedimentary record of Songliao Basin has not yet been cored. For that reason, a scientiic drilling program has been proposed to the International Continental Scientiic Drilling Program (ICDP) to sample the deeper sedimentary record of the Songliao Basin through a new drill hole (Figs. 1 and 2). In order to better constrain the scientiic objectives, feasibility of deep drilling, and study of the core material, an ICDP workshop on “Deep Terrestrial Scientiic Drilling Project of Cretaceous Songliao Basin” was held on 28–30 August 2007 in Daqing, China. The workshop was organized by the China University of Geosciences at Beijing and by the Daqing Oilield and was jointly supported by the ICDP and sponsors from China: the Department of International Cooperation and Technology, Ministry of Land and Resources, China� Department of Basic Research, Ministry of Science and Technology, China (MOST)� Department of Earth Science, National Natural Science Foundation of China (NSFC)� and China Geological Survey. About seventy participants (thirty-one from outside China) from eleven countries took part in the workshop. Three sessions were organized with more than ifty talks to meet the objectives of the workshop including “Evolution of Songliao Basin and East Asia, and Terrestrial Scientiic Drilling Program”, “Terrestrial Environment Change and Paleontological Response to Cretaceous Global Change” and “Cretaceous Paleoceanography”. During the workshop the following ive key scientiic goals for the project were deined: • Figure 1. Location of the Songliao Basin in the tectonic framework of the North China–Mongolia Tract (NCMT). The NCMT is separated from the East Siberian Craton by the Mongolia-Okhotsk suture zone and is marked by the Yinshan-Yanshan Belt in the south and by the Daxing-Ganling Belt in the east. YYF=Yilan-Yitong fault; DMF= Dunhua-Mishan fault; HSZ = Honam Shear Zone; B= basin; F = fault. 60 Scientific Drilling, No. 6, July 2008 • • • Improve understanding of the geodynamics of deep Earth, in particular the relation between the Cretaceous Super-Chron and Large Igneous Provinces� Quantify the biotic response to terrestrial environmental change and the deep biosphere (fossil DNA)� Reine stratigraphic boundaries to improve the correlation between marine and terrestrial stratigraphy� Determine the terrestrial response to OAEs� and identiication of an optimum drilling location. The existing data base comprises, for example, over 250,000 km of seismic relection proiles, some 3-D seismic relection volumes, and about 50,000 wells (without coring). A preliminary site for SK-III has been selected in the center part of the basin (Fig. 2). Finally, meeting participants agreed to form ive strategic teams covering the objectives as outlined above. The goals of this science team are to compose a full drilling proposal and to submit it to ICDP and other potential funding agencies in early 2008. References Bice, K.L., Birgel, D., Meyers, P.A., Dahl, K.A., Hinrichs, K.-U., and Norris, R.D., 2006. A multiple proxy and model study of Cretaceous upper ocean temperatures and atmospheric CO2 concentrations. Paleoceanogr., 21(2206):PA2002, doi:10.1029/2005PA001203. Chen, P.-J., and Chang, Z.-L., 1994. Nonmarine Cretaceous stratigraphy of eastern China. Cretaceous Research, 5(3):245–257, Figure 2. W-E Seismic profile showing the locale of the proposed Songke-III well with stratigraphic interpretation. The vertical blue line indicates the strata to be drilled in rotary mode. The yellow line indicates the planned wireline coring section down to the total depth of ~2700 m. This was done in order to avoid structural complications and to penetrate the most complete stratigraphic section. doi:10.1006/cres.1994.1015. Heimhofer, U., Hochuli, P.A., Burla, S., Dinis, J., and Weissert, H., 2005. Timing of Early Cretaceous angiosperm diversiication and possible links to major paleoenvironmental change. Geology, 33:141–144, doi:10.1130/G21053.1. Qiang, J., Currie, P.J., Norell, M.A., and Shu-An, J., 1998. Two feathered dinosaurs from northeastern China. Nature, 393:753– • Investigate the formation of mass terrestrial hydrocarbon source rock. 761, doi:10.1038/31635. Scotese, C.R., Gahagan, L., and Larson, R.L., 1988. Plate tectonic reconstruction of the Cretaceous and Cenozoic ocean In order to address these overarching research goals, workshop participants recommended that all boreholes (SK-I, SK-II, and the planned SK-III) should be incorporated into the planned ICDP project. The Upper Cretaceous core from SK-1 will especially serve to focus on the K/T boundary� SK-II cores will be analyzed to investigate mid-Cretaceous events� and samples from the proposed SK-III well will focus on the Lower Cretaceous including the J/K boundary, OAEs, and the evolution of the Jehol Biota. Preliminary results from existing boreholes and outcrop studies presented at the workshop showed great promise. During a ield trip to the core curation facility of the Daqing Oilield Company, the workshop participants were able to examine the cores of the SK-I and SK-II wells. basins. Tectonophysics, 155:27–48, doi:10.1016/0040- 1951(88)90259-4. Authors Yongjian Huang and Cheng-Shan Wang, Research Center for Tibetan Plateau Geology, China University of Geosciences, Xueyuan Road 29, Haidian District, 100083, Beijing, People’s Republic of China, e-mail: huangyj@cugb.cn, and the Terrestrial Scientific Drilling of the Cretaceous Songliao Basin Science Team Related �eb Link http://songliao.icdp-online.org An important objective was to assess the feasibility of the deep drill hole (SK-III) in the Songliao Basin and its potential to recover strata older than Albian. Discussions of site selection concluded that the project should aim to core from the Albian Quantou to the Upper Jurassic Huoshiling Formations. Several site selection principles for drilling SK-III were deined as follows: to drill the most complete section, to ind the least thickness of the overlying strata, and to preferentially drill ine-grained, clay-rich deposits. With these principles in mind, existing data were evaluated for Scientific Drilling, No. 6, July 2008 61 Workshop Reports CPCP: Colorado Plateau Coring Project – 100 Million Years of Early Mesozoic Climatic, Tectonic, and Biotic Evolution of an Epicontinental Basin Complex by Paul E. Olsen, Dennis �. Kent, and John �. Geissman doi:10.04/iodp.sd.6.1.008 Introduction Early Mesozoic epicontinental basins of western North America contain a spectacular record of the climatic and tectonic development of northwestern Pangea as well as what is arguably the world’s richest and most-studied Triassic-Jurassic continental biota. The Colorado Plateau and its environs (Fig. 1) expose the textbook example of these layered sedimentary records (Fig. 2). Intensely studied since the mid-nineteenth century, the basins, their strata, and their fossils have stimulated hypotheses on the development of the Early Mesozoic world as relected in the international literature. Despite espite this long history of research, the lack of numerical time calibration, the presence of major uncertainties in global correlations, and an absence of entire suites of environmental proxies still loom large and prevent integration of this immense environmental repository into a useful global picture. Practically insurmountable obstacles to outcrop sampling require a scientiic drilling experiment to recover key sedimentary sections that will transform our understanding of the Early Mesozoic world. To bring our insight into this critical time in Earth history to a new level, we developed the concept of the Colorado Plateau Coring Project (CPCP), an effort to recover continuous core spanning the early Mesozoic (Triassic-Jurassic) section of the Colorado Plateau and adjacent areas. The original basis for this was outlined at the 1999 International Continental Scientiic Drilling Program (ICDP) and U.S. National Science Foundation (NSF) funded International Workshop for a Climatic, Biotic, and Tectonic, Pole-to-Pole Coring Transect of Triassic-Jurassic Pangea (http://www. ldeo.columbia.edu/~polsen/nbcp/pangeainalreport.html, Olsen et al., 1999), section “Western Equatorial Pangea” (http://www.ldeo.columbia.edu/~polsen/nbcp/westpangea. html). Forty-ive researchers from six countries attended the inaugural CPCP planning workshop held 13–16 November 2007, in St. George, Utah. The main goal was to develop a community consensus science plan for the CPCP (http:// www.ldeo.columbia.edu/~polsen/cpcp/CPCP_home_page. html). The participants represented disciplines ranging from geochronology and physical stratigraphy through vertebrate paleontology and paleobotany. A plenary lenary session with speakers highlighting the major science issues, precedents, and geoinformatics priorities was followed by thematic breakout groups. These included Stratigraphy, Geochronology and Magnetostratigraphy, Climate and Environments, Paleontology and Biotic Change, and Geoinformatics and Core-log Outcrop utcrop Integration. ntegration. A half-day ield trip was made to the St. George Dinosaur Discovery Site at Johnson Farm (http://www.sgcity.org/dinotrax/) and Warner Valley outcrops of Triassic-Jurassic strata (Fig. 3), and was followed by a plenary synthesis session. As developed by consensus at the workshop, the goal of the CPCP is to transform our understanding of the interplay between major biotic transitions, global climate change, plate position, and tectonics over 100 Ma of Earth histories (Fig. 2). Overall Concept and Goals Figure 1. Map of the Colorado Plateau (white line) and adjacent areas: [Left] Shaded digital elevation map (courtesy of Andrew D. Birrell http://birrell.org/andrew/reliefMaps/ and http://birrell.org/andrew/ copyright.html); [Right] Generalized geological map showing Permian and Triassic and Jurassic strata (modified from R. Blakely http://jan. ucc.nau.edu/~rcb7/Jurassic_erg_graphics.html). Core areas are: PF, Petrified Forest, Arizona; RP, Rock Point, Utah; SG, St. George, Utah; WT, Ward Terrace, Arizona; SRS, San Rafael Swell, Utah. 6 Scientific Drilling, No. 6, July 2008 Broad questions that could be proitably addressed in the Colorado Plateau venue include the following:: what are the global or regional climate trends vs. plate position changes in “hot house” Pangea� how do largely luvial systems respond to cyclical climate� what are the rates and magnitudes of the transition from the Paleozoic to essentially modern terrestrial ecosystems� and how does the stratigraphy relect the interplay between growth in accommodation, uplift, and eustatic luctuations? Based on these questions, the workshop identiied eight goals attainable by coring of key Triassic/Jurassic sections: 1) Establishment of paleogeographic boundary conditions, particularly changes in paleolatitude. Figure 2. Details are given to the right. 2) 3) 4) 5) 6) 7) 8) Development of the highest-resolution magnetic polarity stratigraphy for Early Triassic through Late Jurassic strata to facilitate detailed regional and global correlation. Determination of how paleoclimates are expressed through time in the sedimentary record of western Pangea. Identiication of the precise stratigraphic position of major global biotic transitions (i.e., Permo-Triassic, Triassic-Jurassic, and Toarcian) Reinement of lithostratigraphic and biostratigraphic correlations, considering regional unconformities and their possible relationship to eustacy and tectonics (c.f., Bachmann and Kozur, 2004). Development of a chemostratigraphic (δ13 C, cuticular CO2 proxy, Nd, Sr, clays, etc.) reference sections. Improvement of U-Pb zircon provenance stratigraphy and geochronology of ash beds. Establishment of links among the temporal evolution of the Colorado Plateau sedimentary record, rifting of Pangea opening of the Atlantic Ocean, and emplacement of basalt provinces (Fig. 2). Coring Plans Given these overall goals, the workshop reached several conclusions that dictated the coring plan. 1) Early Triassic through Late Jurassic Formations including the Morrison Formation should be cored in order to cover the full range of climatic milieus represented by these rocks. Collectively, the group deined a three-tiered coring plan consisting of (1) three relatively thick (~1 km) synoptic intervals that together would yield an overlapping stratigraphic framework for the entire Jurassic and Triassic section, (2) two thinner (<500 m) cored sections that would tie to critical outcrop areas or to expanded critical intervals, and (3) a number of short sections to address more speciic problems or provide regional coverage to the other ive cores that are the nexus of the project. Generalized Colorado Plateau section (Glen Canyon/Kaiparowits Plateau, based on http://jan.ucc.nau.edu/~rcb7/Glen_Can.jpg) with the cored sections recommended by the CPCP workshop participants, a generalized evaporation-precipitation (E-P) curve loosely based on climate sensitive facies, and some major geological and biological events (* actual boundary may or may not be present in rock section). See Fig. 1 for core area abbreviations. Note that the relative thicknesses of various stratigraphic units are generally different than what is shown in the color section and not the same between different coring areas. The ive major stratigraphic units shown here were deposited under dramatically changing climatic conditions that constitute the Triassic and Jurassic of the Colorado Plateau: the Early to Middle Triassic Moenkopi Formation (marginal marine and coastal sabka to semiarid luvial and loodplain, minor eolian); the Late Triassic Chinle Group (humid to semiarid luvial to lacustrine, some eolian near top); the latest (?) Triassic-Early Jurassic Glen Canyon Group (semiarid to arid, major eolian, luvial, lacustrine); the Middle to Late Jurassic San Rafael Group (marine to coastal sabka, major eolian and luvial arid to semiarid; from http://www.nps.gov/ arch/); and the Late Jurassic Morrison Formation (semiarid to humid, luvial and lacustrine). Determining the precise nature and origin of the large climatic transitions represented by these units is a major goal of the CPCP. 2) Superposition is paramount. Evaluation of the critical Early Mesozoic transitions is required d of all Early Mesozoic units in clear superposition. The ive major stratigraphic units identiied as major coring targets relect, from oldest to youngest: arid (Moenkopi)� humid to semiarid (Chinle)� very arid (Glen Canyon and San Rafael)� and return to semiarid and humid (Morrison) (Figs. 2 and 4). These climate transitions have been explained in several ways—translation of the North American plate from equatorial to mid-latitudes through zonal climate belts (Dickinson, 2005� Kent and Muttoni, 2003� Kent and Tauxe, 2004)�� large scale changes in the climate system involving changes in the non-zonal components of the climate system, particularly the monsoon (Kutzbach and Gallimore, 1989� Parrish, 1995� Rowe et al., 2007)�� or luctuations in greenhouse gases like CO2 (e.g., McElwain et al., 1999� Kürschner, 2001). These fundamentally different hypotheses remain untested because the temporal evolution of major boundary conditions, most notably latitude, has not been resolved to a useful level of precision (Tauxe and Kent, 2004� Tan et al., 2007). 3) Internal time calibration needed. Correlation of the Plateau sequence is presently based on low-resolution non-marine biostratigraphic approaches,, and it does not provide clear biogeographic patterns or determination of the rates of biotic change in these very fossiliferous sequences. None of the major intervals of biotic change (Permo-Triassic� Triassic-Jurassic� or Toarcian) are located with precision in this succession. A combination of polarity stratigraphy along with geochronologic dates from ash deposits and dispersed grains will allow global correlations, including: 1) Triassic and Early Jurassic reference sections (Szurlies, 2007)� 2) the astronomically calibrated polarity time scale (Kent and Olsen, 1999, 2008� Olsen and Kent, 1999� Hounslow et al., 2004� Kemp and Coe, 2007)� 3) the Germanic basin (Bachmann and Kozur, 2004)� 4) fully marine Tethyan sections (Muttoni et al., 2005� Channell et al., 2003� Gallet et al., 2007)� 5) non-marine Jurassic to Early Cretaceous sequences of China (Feursich et al., 2002� Yao et al., 2003� Xu, 2005)� Scientific Drilling, No. 6, July 2008 6 Workshop Reports and 6) possibly, the marine magnetic anomaly M-sequence (Channell et al., 1995� Sager et al., 1998). 4) Minimize hiatuses. Acquiring as much stratigraphic scope as possible through the more continuous units and testing any paleomagnetic reversal sequences across geography by designing stratigraphic overlap between cores will help overcome signiicant unconformities and possible smaller and cryptic hiatuses. The thickest sections, least likely to be affected by rampant hiatuses, are not conined to a single area in the Colorado Plateau because of lateral shifts in the basin’s depocenters. Several cores will be necessary to get the most favorable sections of each of the units. However, the thick sections proposed for coring are far from comparable surface outcrops,, and thus,, subsidiary sections more proximal to sources of the surface data must be cored as well. The goal is to provide a long enough section with unambiguous ties to the outcrop and suficient stratigraphic scope to correlate with the main, long cores. St. George and Tuba City sections appear to span the same overall section, they are actually critical complements. The Moenkopi and latest (?) Triassic-Early JurassicTriassic-Early Jurassic Moenave formations are well-developed, -developed, developed, cyclical, and probably relatively complete in the St. George area, yet the Chinle Group is very thin and erosionally truncated. In the Tuba City area, the Chinle is very well-developed, -developed, developed,, but the Moenkopi is very thin and erosionally truncated. Also, the Moenave lacks the well-developed, cyclical lacustrine strata present around St. George. The two medium depth sections (Fig. 2) are targeted for 1) the Rock Point area (north of Round Rock, Utah), ~600 m from basal Wingate Formation to Permian Kiabab Formation, 5) Thick eolianite successions should be avoided while key limestone and eolianite tongues must be intersected for age control by lateral correlation to outcrop. Using these ive principless above,, three areas identiied for long (~1 km) cores are, from the uppermost stratigraphic interval downward ward (Figs. 1 and 2): 1) Dry Mesa (east side of San Rafael Swell, UT), ~1400 m from basal Cretaceous Cedar Mountain Formation to the Permian Kaibab Formation� 2) St. George (west of the Hurricane fault), ~1100 m from locally basal Navajo Formation to Permian Kaibab Formation� and 3) Tuba City (north of Ward Terrace): ~700 m from basal Navajo Formation to Kaibab Formation. Although the Figure 3. Examples of dinosaur tracks at the St. George Discovery Site at Johnson Farm in the lower Whitmore Point Member of the Moenave Formation: [A] Example of natural cast of Eubrontes giganteus (~35 cm long), plausibly made by a large theropod dinosaur similar to Dilophosaurus from the lower Kayenta Formation; [B] small theropod dinosaur footprints of the “Grallator” and “Anchisauripus” types (~10–15 cm long each). The importance of these fossil assemblages is that they document the terrestrial assemblages just after the Triassic-Jurassic extinction event that surprisingly is overwhelmingly dominated by carnivores. 64 Scientific Drilling, No. 6, July 2008 Figure 4. Details are given below. Although the American Southwest, including the Colorado Plateau, is famous for spectacular exposures in striking badlands, the thickest sections of key time intervals are often projected from the subsurface. The most continuous sections in outcrop are often exposed as inaccessible vertical cliffs or are heavily weathered and geochemically altered, precluding research at the appropriate level of detail. Because of low bedding dips, the assembly of sections spanning large stratigraphic thicknesses requires long-distance traverses that often compromise the essential assumption of superposition because of facies changes. The problems are amply revealed by repeated attempts in the literature at compiling long, high-resolution sections that describe the succession in any speciic area. Long, continuously cored intervals tied to outcrop in key areas are required for further substantial progress. Opportunities and problems of working only with outcrops present themselves in examples of superb near-100% outcrops, especially of muddy facies (Fig. 4). Mudstones are often bentonitic and with a partial volcanic source, which means there are datable ashes; however, it also means that the outcrop surfaces present horrendous sampling problems where freshness and physical integrity are at a premium as for geochemistry or paleomagnetics. Two examples include the Late Jurassic Morrison Formation (Fig. 4A and 4B) and the Late Triassic Chinle Group (Fig. 4C and 4D). Fig. 4A, Brushy Basin Member of the Morrison Formation west of Green River, Utah (from http://en.wikipedia.org/wiki/Morrison_Formation); Fig. 4B, typical “popcorn” surface of bentonitic mudstone of the Brushy Basin Member of the Morrison Formation west of Green River, Utah (same source as 4A); Fig. 4C, “popcorn” surface of the Chinle Group near Bluewater Creek, NM (Stop 1 of Lucas et al., 2007), with fragmentary weathered metoposaur amphibian dermal bones; and Fig. 4D, outcrops of bentonitic Painted Desert Member of the Petriied Forest Formation of the Chinle Group in Petriied Forest National Park with the U-Pb dated Black Forest Bed (Riggs et al., 2003) outcropping as the white bed in foreground. and 2) the Petrified Forest area (within Petriied Forest National Park, AZ), ~400 m from Sonsela (mid-Chinle) to Permian. The Rock Point area is a critical target because it exposes the Triassic-Jurassic boundary section in the largely eolian Wingate Formation, based on both vertebrate paleontology and magnetostratigraphy, and it is a natural complement to the lacustrine-dominated Moenave Formation near St. George. The Petriied Forest area has produced the bulk of the Chinle fauna and lora, as well as dated ash beds, and it is a natural complement to the Chinle section in the Tuba City area. The workshop concluded that the geophysical logs of the core holes and cores will be critical in tying cores to outcrop (Szurlies et al.,, 2003). Ne�t Steps Data management scenario for the CPCP showing the relationship between data gathering (i.e., from the cores and core holes) and the low of information and samples derived from it to community access systems. Acronyms are: DIS, Drilling Information System; CoreWall, a real-time stratigraphic correlation, core description and data visualization system (http://www.evl.uic.edu/cavern/corewall/index.php); SESAR, System for Earth Sample Registration (http://www. geosamples.org/); PaleoStrat, a community digital information system for paleontology and sedimentary geology (https://www. paleostrat.com/); IGSN, International Geo Sample Number; SDDB, The Scientiic Drilling Database is the repository for data from operations of ICDP (http://www.icdponline.org/contenido/lakedb/front_content. php); EarthChem, system to facilitate the preservation, discovery, access, and visualization of geochemical datasets (http://www. earthchem.org/); MagIC, Magnetics Information Consortium (http://www.earthref. org/MAGIC/). A robust and effective data management/geoinformatics system, accessible through a CPCP Data Portal, will facilitate and support the science and provide the basis for education and outreach efforts. This will include coupling the Drilling Information System (DIS) of the ICDP with System for Earth Sample Registration (SESAR; www. geosamples.org), EarthChem (www. earthchem.org), CoreWall (www.evl.uic.edu/ cavern/corewall), and PaleoStrat (www. paleostrat.org), a core-core hole-log integration system, and a novel digital framework of regional geology (Fig. 5). The CPCP workshop Figure 5. Details are given to the right. endorsed aiming full drilling proposals to ICDP and U.S. .S. S.. 37(7):362. National Science Foundation (NSF) Continental Dynamics. Feursich, F.T., Sha, J.G., Jiang, B.Y., and Pan, Y.H., 2002. High resoluIn preparation for this,, there will be an international CPCP tion palaeoecological and taphonomic analysis of Early proposal planning workshop in Albuquerque, N.M., to be Cretaceous lake biota, western Liaoning (NE-China). advertised in the near future. Palaeogeogr.. Palaeoclimatol.. Palaeoecol.., 253:434–457. References Bachmann,, G.H.,, and Kozur,, H.W.,, 2004. The Germanic Triassic: correlations with the international chronostratigraphic scale, numerical ages and Milankovitch cyclicity. Hallesches Jahrbuch Geowissenschaften B, 26:17–62. Channell, J.E.T., Erba, E., Nakanishi, M., and Tamaki, K., 1995. Late Jurassic-Early Cretaceous time scales and oceanic magnetic anomaly block models.. In n Berggren, W.A., Kent, D.V., Aubry, M.-P., and Hardenbol, J. (Eds.), ds.), ),, Geochronology, Time Scales and Global Stratigraphic Correlations. Tulsa, Okla. (SEPM SEPM (Society for Sedimentary Geology)) SEPM Special Volume No. 54, p. 51–63. Channell, J.E.T., Kozur, H.W., Sievers, T., Mock, R., Aubrecht, R., and Sykora, M., 2003. Carnian-Norian biomagnetostratigraphy at Silicka Brezova (Slovakia): correlation to other Tethyan sections and to the Newark Basin: Palaeogeogr.. Palaeoclimatol.. Palaeoecol Palaeoecol.,, 191:65–109. :65–109. 65–109. Dickinson, W.R., 2005.. Redbed paleomagnetism and Mesozoic paleolatitude of the Colorado Plateau. Geol.. Soc.. Am.. Abst.. Prog Prog.,, Gallet,, Y., Krystyn,, L., Marcoux,, J., and Besse,, J., 2007.. New constraints on the End-Triassic (Upper Norian-Rhaetian) magnetostratigraphy.. Earth Planet.. Sci.. Lett Lett.,, 255:458 :458 458 –470. Hounslow, M.W., Posen, P.E., and Warrington, G., 2004.. Magnetostratigraphy and biostratigraphy of the Upper Triassic and lowermost Jurassic succession, St. Audrie's Bay, UK.. Palaeoceanogr.. Palaeoclimatol.. Palaeoecol.., 213:331–358. :331–358. 331–358. Kemp, D.B.,, and Coe, A.L., 2007. A nonmarine record of eccentricity forcing through the Upper Triassic of southwest England and its correlation with the Newark Basin astronomically calibrated geomagnetic polarity time scale from North America. Geology, 35(11):991–994. :991–994. 991–994. Kent, D.V., and Muttoni, G., 2003. Mobility of Pangea: Implications for Late Paleozoic and Early Mesozoic paleoclimate.. In LeTourneau, P.M., and Olsen, P.E. (Eds.), Eds.), ds.), The Great Rift Valleys of Pangea in Eastern North America, Volume 1, Tectonics, Structure, and Volcanism. New York (Columbia Columbia University Press),11–20. ),11–20. ,11–20. Kent, D.V., and Olsen, P.E., 1999.. Astronomically tuned geomagnetic polarity time scale for the Late Triassic.. J.. Geophys.. Res Res.,, Scientific Drilling, No. 6, July 2008 65 Workshop Reports 104:12831–12841. :12831–12841. 12831–12841. Kent, D.V., and Olsen, P.E., 2008. Early Jurassic magnetostratigraphy and paleolatitude from the Hartford continental rift basin (eastern North America): Testing for polarity bias and abrupt polar wander in association with the Central Atlantic Magmatic Province. J. Geophys. Res., 113, B06105, doi:10.1029/2007JB005407. Kent, ent, D.V., and Tauxe, L., 2005. Corrected Late Triassic latitudes for continents adjacent to the North Atlantic. Science, 307:240–244. –244. 244. Kürschner, W.M.,, 2001. Leaf sensor for CO2 in deep time. Nature, 411:247–248. Kutzbach, J.E.,, and Gallimore, R.G.,, 1989. Pangean climates: megamonsoons of the megacontinent.. J. Geophys. Res., 94:3341–3357. Lucas, S.J., Heckert, A.B., Spielmann, J.A., Tanner, L.H., and Hunt, A.P., 2007. First Day: Middle and Upper Triassic stratigraphy, sedimentology, and paleontology of west-central New Mexico. In Lucas, S.J., and Spielmann, J.A. (Eds.), Eds.), ds.),, Triassic of the American West, New Mexico Museum of Natural History & Science Bulletin 40, 169–180. McElwain, J.C., Beerling, D.J., and Woodward, F.I., 1999. Fossil plants and global warming at the Triassic-Jurassic boundary. Science, 285(5432):1386–1390. Muttoni, G., Meco, S., and Gaetani, M., 2005.. Magnetostratigraphy and biostratigraphy of the Late Triassic Guri Zi Section, Albania: Constraint on the age of the Carnian-Norian boundary.. Rivista Italiana di Paleontologia e Stratigrafia, 111:233 :233 –245. Olsen, P.E., and Kent, D.V., 1999. Long-period Milankovitch cycles from the Late Triassic and Early Jurassic of eastern North America and their implications for the calibration of the early Mesozoic time scale and the long-term behavior of the planets. Phil.. Trans.. Roy.. Soc Soc. London A, 357:1761–1787. Olsen, P.E.,, Kent, D.V., and Raeside, R., 1999.. International workshop for a climatic, biotic, and tectonic, pole-to-pole coring transect of Triassic-Jurassic Pangea. Newsletter, ICDP (Potsdam), 1:16–20. :16–20. 16–20. Parrish, J.T.,, 1995. Geologic evidence of Permian climate. In Scholle, P.A., Peryt,, T.M., and Ulmer-Scholle, D.S. (Eds.), Eds.), .),, The Permian of Northern Pangea, Paleogeogr., .,, Paleoclimatol.. Stratigr.. vol. 1 1, Berlin (Springer Springer Verlag), ), 53–61. Riggs, M.R., Ash, S.R., Barth, A.P., Gehrels, G.E., and Wooden, J.L.,, 2003. Isotopic age of the Black Forest Bed, Petriied Forest Member, Chinle Formation, Arizona: An example of dating a continental sandstone. Geol.. Soc.. Am.. Bull.., 115:1315–1323. Rowe,, C.M., Loope,, D.B., Oglesby,, R.J., Van der Voo,, R., and Broadwater,, C.E.,, 2007. Inconsistencies between etween Pangean reconstructions econstructions and basic asic climate limate controls. ontrols. Science, 318:1284–1286. Sager,, W.W., Weiss, M.A., Tivey, M.A., and Johnson, H.P., 1998.. Geomagnetic polarity reversal model of deep-tow proiles from the Paciic Jurassic "Quiet Zone" J.. Geophys.. Res Res.,, 103:5269–5286. :5269–5286. 5269–5286. Szurlies, M., Bachmann, G.H., Menning, M., Nowaczyk, N.R., and Käding, K.-C., 2003. Magnetostratigraphy and high-resolution lithostratigraphy of the Permian-Triassic boundary interval in Central Germany. Earth Planet. Sci. Lett., 66 Scientific Drilling, No. 6, July 2008 212(3-4):263–278. Szurlies, M., 2007. Latest Permian to Middle Triassic cyclo- magnetostratigraphy from the Central European Basin, Germany: Implications for the geomagnetic polarity timescale: Earth Planet. Sci. Lett., 261:602–619. Tan, X., Kodama, K.P., Gilder, S., and Courtillot, V., 2007. Rock magnetic evidence for inclination shallowing in the Passaic Formation red beds from the Newark basin and a systematic bias of the Late Triassic apparent polar wander path for North America. Earth Planet. Sci. Lett., 254:345–357. Tauxe, L., and Kent, D.V., 2004. A simpliied statistical model for the geomagnetic ield and the detection of shallow bias in paleomagnetic inclinations: Was the ancient magnetic ield dipolar? In Channell, J.E.T., Kent, D.V., Lowrie, W., and Meert, J. (Eds), Timescales of the Paleomagnetic Field, AGU Geophysical Monograph 145,101–115. Xu, D.Y., 2005. Astro-geologic time scale and the advancements of cyclostratigraphy. J. Stratigr., 29:635–640 (in Chinese with English abstract). Yao, Y.-M., Fu, G.-B., Xu, D.-Y., Qin, J., and Yao, S., 2003. Preliminary study on the high-resolution cyclostratigraphy of the Jurassic system in Turpan-Hami basin, Xinjiang. J. Stratigr., 27:122–128 (in Chinese with English abstract). Authors Paul E. Olsen, Lamont-Doherty Earth Observatory (LDEO) of Columbia University, 61 Route 9W, Palisades, N.Y., 10964-1000, U.S.A., e-mail: polsen@ldeo.columbia.edu. Dennis V. Kent, Department of Earth & Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, N.J. 08854, U.S.A. and Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, N.Y. 10964,, U.S.A. John W. Geissman, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, N.M., 87131, U.S.A. Related �eb Links http://www.earthchem.org/ http://www.earthref.org/MAGIC/ http://www.evl.uic.edu/cavern/corewall/index.php http://www.geosamples.org/ ht t p://w w w.icdp - onl i ne.org/contenido/ la kedb/f ront _content.php ht t p://w w w.ldeo.columbia .edu/~polsen/cpcp/CPCP_ home_page.html ht t p://w w w.ldeo.columbia .edu/~polsen/cpcp/CPCP_ dosecc_nsf.html http://www.ldeo.columbia.edu/~polsen/nbcp/pangeainalreport.html http://www.ldeo.columbia.edu/~polsen/nbcp/westpangea. html https://www.paleostrat.com/ http://www.sgcity.org/dinotrax/ Figure Credits Fig.. 1: courtesy of Andrew D. Birrell http://birrell.org/ andrew/reliefMaps/ and http://birrell.org/andrew/copyright.html Workshop Reports ICDP Workshop on Borehole Monitoring at the Nankai Subduction Zone: Building a Land-Ocean Borehole Network to Study the Seismogenic Zone by y Takeshi Sagiya doi:10.04/iodp.sd.6.1.008 Examples of subduction processes are currently investigated around the Kii Peninsula, Honshu Island by Japanese as well as international projects. The most well-known is the NanTroSEIZE project conducted by the Integrated Ocean Drilling Program (IODP). Drilling (riserless) with the drillship Chikyu started southeast off the Kii Peninsula in October 2007. In addition, the Japanese government launched a new project called Dense Ocean loor Network System for Earthquakes and Tsunamis (DONET) to install an integrated ocean bottom cable system for continuously monitoring earthquakes and tsunamis between the Kii Peninsula and the NanTroSEIZE drilling site. On land on the Kii Peninsula, an array of shallow boreholes for monitoring changes in groundwater level and strain is being constructed by Japan’s National Institute of Advanced Industrial Science and Technology (AIST, Fig. 1). As part of the latter project, the International Continental Scientiic Drilling Program (ICDP) organized and funded a workshop to prepare for land-based intermediate depth drilling to install monitoring equipment complementing the AIST and NantroSEIZE projects. The “ICDP Workshop on Borehole Monitoring at the Nankai Subduction Zone: Building a Land-Ocean Borehole Network to Study the Seismogenic Zone” was conducted on 20–23 August 2007 at Nagoya University. Thirty-ive scientists from four countries participated. Eighteen presentations addressed the seismic activity along the Nankai Trough Figure 1. Location map of the Nankai Trough and boreholes in Kii Peninsula. Circles denote drilling sites in the NanTroSEIZE project. Triangles on land denote IST boreholes. subduction zone, geologic background of the Kii Peninsula, present status of various ongoing projects (NanTroSEIZE, DONET, etc.), and state-of-the-art observatory technologies. Other key topics included pore pressure measurements and technical aspects of the planned monitoring system and its installation. The discussion of the merits of pore pressure measurement led to the conclusion that such data must be one of the main parameters to be monitored in the Nankai Trough subduction complex. For strain measurements, two options were considered in detail. An integrated monitoring system of the Tono Research Institute of Earthquake Science in Mizunami, Japan, shows high sensitivity and good stability. Alternatively, optical iber strain meters can be installed outside the borehole casing to allow using the boreholes for other purposes such as repeated downhole logs or permanent measurements inside casing. Another inding was that seismological monitoring and analysis should be included to study non-volcanic deep tremors. A major part of the workshop was dedicated to preparation of a drilling proposal including discussion of prioritized scientiic targets. Considering recent indings like non-volcanic deep low-frequency tremors (e.g. Obara, 2002), slow slip events (e.g. Ozawa et al., 2002), and ultra-slow earthquakes (e.g. Ito et al., 2007), participants agreed that the goal of drilling and monitoring is to resolve the complex behavior of the plate boundary megathrust at the deeper end of the locked zone. A ield trip was made to the Kii Peninsula to visit two geologic sites exhibiting Miocene igneous acidic rocks characterizing the southeastern part of the Kii Peninsula. The integrated borehole groundwater observatory constructed by AIST visited Kumano City (Fig. 2). The observatory was designed to detect precursory ground water level changes before a large megathrust earthquake (there were reports of ground water level change before the 1946 Nankai earthquake) and to Figure 2. Field trip to the integrated borehole investigate various groundwater observatory of AIST. Scientific Drilling, No. 6, July 2008 67 Workshop Reports plate boundary phenomena with precise observation with strainmeter, tiltmeter, and a seismograph. Finally, Kata village of Owase City, Japan was visited, where tsunami run-up heights were recorded and displayed on a telegraph pole (Fig. 3). The 1944 Tonankai and the 1854 Anse-Tokai earthquakes also shook this area. This display teaches us that the last earthquake in 1944 was a moderate one, and the region may have to prepare for a stronger one similar to the 1854 event. The whole workshop was very successful in raising the understanding on various ongoing projects, introducing state-of-the-art monitoring techniques to potential project proponents as well as technical problems to be resolved. It also deined the goals and milestones towards a full drilling proposal planned for submission to ICDP by fall 2008. Acknowledgements s The author would like to express sincere thanks to ICDP and the Japan Drilling Earth Science Consortium (J-DESC) for their inancial support of the workshop. References Ito, Y., Obara, K., Shiomi, K., Sekine, S., and Hirose, H., 2007. Slow earthquake coincident with episodic tremors and slow slip events. Science, 315:503–506, doi:10.1126/science.1134454. Obara, K., 2002. Nonvolcanic deep tremor associated with subduction in southwest Japan. Science, 296:1679–1681, doi:10.1126/science.1070378. Ozawa, S., Murakami, M., Kaidzu, M., Tada, T., Sagiya, T., Yarai, H., and Nishimura, T., 2002. Detection and monitoring of ongoing aseismic slip in the Tokai region, central Japan. Science, 298: 1009–1012, doi:10.1126/science.1076780. Figure 3. Display of tsunami heights (in red on pole) in Kata village, Owase City. Author Takeshi Sagiya agiya, Research Center for Seismology, Volcanology, and Disaster Mitigation, Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 Japan, e-mail: sagiya@seis. nagoya-u.ac.jp. Upcoming Workshops Marine Research Drilling in the Atlantic (Magellan �S Series) Scientific Drilling of Sediment in Lake Ohrid (SCOPSCO) 10–12 September 13–17 October 2008, 2008, Montpellier, Ohrid, Republic of France Macedonia Partial travel support is available. Please contact Bernard Coakley (bernard.coakley@gi.alaska.edu) or Ruediger (rstein@awi-bremerhaven.de) for Stein further information. Scientific Drilling for �uman Origins Participation on invitation only. Conveners: Scientiic collaboration on past speciation Marguerite Godard (Université Montpellier conditions in Lake Ohrid (SCOPSCO), 2), Gretchen Früh-Green (ETH Zurich), and Republic of Macedonia, will be discussed to 17–21 November 2008, Christopher MacLeod (Cardiff University). prepare drilling of sediments in the oldest Addis Ababa, Ethiopia MacLeod, e-mail: lake in Europe. See details at: http://ohrid. Contact: Dr. C. J. macleod@cardiff. ac.uk icdp-online.org Ultra-�igh Resolution Geological Records of Past Climate Change Arctic Ocean �istory �orkshop 3–5 November 2008, 29 Sept.–1 Oct. 2008, Bremerhaven, Germany Potsdam, Germany Application Deadline: See details at: http: //www.iodp.org/climatews-workshop/ 68 Scientific Drilling, No. 6, July 2008 Following recent, successful lake drilling projects in Africa 24 August 2008 To participate in this workshop, details are given at: www.oceanleadership.org/arctic. with implications for human origins, the time is right to consider new targets for drilling. A highly promising approach to this goal is to target lacustrine sedimentary sequences currently exposed on-land, in sedimentary basins of world-class importance to hominin evolutionary history. See details at: http:// www.magadi.icdp-online.org News and Views 7th International Symposium for Subsurface Microbiology new goals and effectively meets the chal- ICDP Drilling Training lenges of future ocean drilling will be drafted Geoscientists during 2010. The conference will be open to Shizuoka, Japan, 16–21 November 2008, all scientists with an interest in scientiic Regular Registration: 30 September 2008 ocean drilling. More information at http:// The application of molecular approaches to the study of subsurface microbial ecology has been most encouraging in the past decade. As would naturally be expected, the www.iodp.org. For more sions need special management skills, but this know-how is often not part of their Internships Available in Scientific Drilling deeper we delve, the more diverse the discoveries. leading drilling mis- academc background. Industry helps by providing training, but scientists usually start learning on the job during a drilling project. DOSECC Internships pro- The Operational Support Group of ICDP mote student involvement in offers a comprehensive one-week training projects where drilling has course covering key topics of scientiic drill- provided data and materials ing to address this issue. The idea is not only for study. Students can under- to transfer speciic knowledge and expertise take research related to ongo- but also to demonstrate the dependencies and ing or past drilling efforts. The internships linkages among different subjects involved, are open to undergraduate or graduate stu- especially between engineering and science. Application Deadline dents, and primary and secondary school Classes are taught by specialized instructors 30 September 2008 teachers worldwide. Internship funding will with practical industrial or academic experi- be available in the summer of 2009 and bud- ence in several basic modules. Content and gets of $2,000 to $5,000 are appropriate. See training level can be customized (deadline for application details at: http://www.dosecc. training proposals is 15 January each year), org/html/internship.html. Contact: David and costs for invited participants are paid by Zur, e-mail: dzur@dosecc.org. ICDP. Distinguished Lecture Series many at the drill site of the KTB from 5–9 detailed information, contact: Prof. Kenji Kato (Chair), Sanami Nishida (Secretary), e-mail: shizissm@ipc. shizuoka.ac.jp. Distinguished Lecturer Program ECORD is sponsoring an initiative for a lecture series to be given by leading scientists involved with the IODP. This program is designed to bring the exciting scientiic discoveries of the IODP to the geosciences community. For more information, please contact: ESSAC Ofice (ECORD Science Support & Advisory Committee)� e-mail: DOSECC’s Distinguished essac@cerege.fr, and apply via: http://www. Lecture Series makes avail- doodle.ch/4nxs78whk6xmedh9. able geoscientists to give talks or lectures on their areas of IODP Conference on Future Scientific Ocean Drilling The IODP expertise. DOSECC covers travel costs for the lecturers, is funded for the period 2003–2013, and is and the host institution is asked to provide food and lodging costs. Lecture themes include: The 2007 ICDP Training was held in GerNovember, attracting 33 scientists from 19 countries. A highlight of the training, in addition to the lectures at the fully equipped ield lab and core repository, was an excursion to two drill sites, at a 4.5-km-deep geothermal well and a site where the newly developed scientiic drilling facility InnovaRig was located. ICDP training is usually held in conjunction with an active drilling project to bridge now starting to plan for its renewal beyond • Paleoclimate and Human Evolution� the gap between the classroom and practical 2013. A community-wide, major conference • Global sea-level changes over the past 100 applications in the ield and to provide train- on future directions of scientiic ocean drilling is planned for 23–25 September 2009. The meeting location will be the University of Bremen, Germany. Based on this conference and million years� ing on the job. • Celestial Mechanics, Mass Extinctions, and Giant Volcanic Eruptions� • 32 Million Years of Astronomical Forcing other planning documents including past and of Climate from Tropical, Triassic-Jurassic future workshops, a science plan that deines Pangea� The next ICDP training is scheduled for 6– 10 October 2008 in Germany. Further information: http://www.icdp-online.org Contact: Thomas Wöhrl, ICDP, GFZ Potsdam, e-mail: woehrl@gfz-potsdam.de • New insights into African paleoclimate from the Lake Malawi Drilling Project� • Sublacustrine Paleoseismology: Coring Earthquake Event Horizons in the Great Salt Lake� and • Terrestrial Impact Cratering: The Earth’s Record of Bombardment from Space. Further details and speaker contact information is available at Chikyu and the boundless ocean view from IODP Exp. 316. Photo courtsey JAMSTEC/IODP. MSP�DS Professional Development Program Partnering with the MSPHDS (Minorities Striving and Pursuing Higher Degrees of Success in Earth Sys- http://www.dosecc. tem Science) Professional Development Pro- org/ ht m l/dist i ng uished _ lect ures.ht m l. gram, the Consortium for Ocean Leadership To apply, contact: David Zur, e-mail: dzur@ supported four students to attend the IODP dosecc.org. Science Steering and Evaluation Panel meet- Scientific Drilling, No. 6, July 2008 69 News and Views ing in Busan, Korea. Mentored by panel members, the students gained an inside look at the Joint EUROFORUM 008 For the irst time, proposal process for a large-scale science Aurora Borealis: A European Project IODP and ICDP held The European Commission identiied a joint EUROFORUM developing of the icebreaker Aurora Borelis meeting during the for the highest scientiic priority. A European EGU General Assem- Research Icebreaker Consortium (ERICON) bly on of 15 institutions, funding agencies and com- 17 April 2008. This afternoon meeting pro- panies from 10 European nations, including vided eleven talks in a platform to exchange Russia, has been formed to develop manage- diversity/professionals latest research highlights of various drilling ment structures for this unique facility and to projects covering new NanTroSEIZE results, implement it into the European Research New Member of IODP:Australia paleoclimate science on various marine and Area. The Alfred Wegener Institute for Polar terrestrial archives, as well as deep subsur- and Marine Research coordinates the inal face life and the planned volcanic risk engineering work for the development with research at Campi Flegrei. funds from the German Federal Ministry for program and had the opportunity to meet and discuss science issues with international colleagues. One student commented, “The importance of writing succinct proposals with clear and concise objectives was a great lesson learned by observing the meeting.” See details at http://oceanleadership.org/ An agreement between the Austra- in Vienna lian Research Coun- The EUROFORUM was followed by a Joint Science and Education. In December 2007, cil and the Lead Agencies of IODP to make Town Hall Meeting for latest program devel- SCHIFFKO GmbH was awarded a design Australia an Associate Member of IODP effec- opment updates and discussions. contract for the initial design concept (Fig.1), tive 1 January 2008 was in the process of inal signing by early July 2008. The Australian membership is intended to be amended by First Joint IODP-ICDP Town �all Meeting held in Japan membership of New Zealand within a joint J-DE SC sponsored AUS-NZ consortium. the first joint IODPICDP town hall New Members of ICDP: Sweden and Switzerland meeting on 27 May, while Japan Geosci- The Swedish Deep Drilling Program (SDDP) was initiated in early 2007 to address fundamental issues of the dynamic Earth system including (Palaeo)proterozoic orogens or ore genesis. The SDDP working group is planning a drilling program to attract ence Union Meeting 2008 was also being held in Japan. The town hall event got ~100 scientists and graduate students together to exchange program news and other informaton. This will be an annual event. der documentation. Currently the ice-tank and open water tests are being carried out. The new technical details include: • 55 MW, twin hull icebreaker • 201 m length, 49 m width • 15 kn max. speed • dynamic positioning, two moon pools • riserless drilling, in max. 5000 m water for 1000 m core Contact: Dr. Nicole Biebow, AWI, 27568 Bremerhaven, Germany, e-mail: nicole. biebow@awi.de, web link at : www. eri-aurora-borealis.eu. The Thrill to Drill in Japanese The ICDP brochure “The Thrill to Drill” funding for four world-class deep boreholes was produced jointly by ICDP and J-DESC over a ten-year period. Recently, the strongly anticipated inan- Japan in 2006 in English, and now its Japanese cial support for a Swedish ICDP membership version is available from J-DESC or can be has been granted by the Swedish Research downloaded from www.j-desc.org. Council, greatly supporting the efforts of SDDP. Please visit the SDDP website at http://www.sddp.se for information. Contact: general arrangement planning, and full ten- Henning Lorenz, Deep Earth Academy’s Sea90E Poster and �eb Site Deep Earth Acade- e-mail: my’s poster and Web henning.lorenz@geo.uu.se Figure 1. Side view of the Aurora Borelis, detailed cross sections. site won a 2008 Distin- ICDP Switzerland was initiated during the Swiss ICDP meeting on 1 February 2008 by guished about ifty scientists. Several are involved in Award from the Associ- Achievement ongoing or planned paleoclimate drilling ation of Educational Publishers in the cate- projects and are discussing projects in gory of curriculum for teaching science for azimuth Quaternary deep Alpine valleys and the Ivrea grades for six to eight, and more information gears on the D/V Zone. The Swiss National Science Foundation at http://www.aepweb.org/awards/curric- Chikyu was discovered during a dry-dock sur- recently assured the Swiss participation for win.htm. It features a bathymetry map, scien- vey in the late spring of 2008. Fabrication and the D/V Chikyu Undergoes Repairs Damage to the thruster Flavio tist proiles, student Q&As, and science reassembly of six new gears are expected to lavio.anselmetti@ challenges. See poster at http://www.ocean- be completed by January 2009, after which eawag.ch, and web link: http://www.swiss- leadership.org/learning/materials/posters/ NanTroSEIZE drilling operations will resume drilling.ethz.ch. sea90poster. (see back cover for schedule). next ive Anselmetti, years. e-mail: Contact: 70 Scientific Drilling, No. 6, July 2008 Views — Discussion Forum Comment: Magnetization of the Oceanic Crust Mission Moho Workshop. We would like to take this opportunity to emphasize the following points, which were also articulated in the C. Harrison Mission Moho proposal that was submitted to IODP in April 2007 : In the March 2007 issue of Scientific Drilling there is a report of the “Mission - Although Site 1256D is the site for cur- Moho” meeting. Mission Moho is being pro- rent deep drilling in the upper crust, it will posed to the Integrated Ocean Drilling not necessarily be the deep crustal, MoHole Program to investigate the formation and evo- site. The latter has yet to be chosen. Site lution of oceanic lithosphere. Deep drilling selection for deep drilling in the fast-spread has been one of the main objectives of the ocean crust faces a few major trade-offs, dom- drilling program ever since the irst phase inated by water depth vs temperature at (Deep Sea Drilling Project) started in 1968. Moho, and also magnetic geometry vs Shortly afterwards, a committee was formed to look at scientiic objectives of deeper penetration into the oceanic crust. Part of the rationale for deeper penetration was to understand how the oceanic crust is magnetized and how this magnetization contributes to the formation of sea loor spreading magnetic anomalies. More recently the COMPLEX Meeting (May 1999, Vancouver, Canada ht tp://w w w.odplegacy.org/PDF/Admin/ Long_Range/COMPLEX.pdf) had a section on “How do marine magnetic anomalies relate to crustal architecture, cooling, and alteration”. It is pointed out that “To fully understand the depth distribution of magnetization requires drilling of an intact crustal section”. The CONCORD report (July 1997: Tokyo, Japan, http://www.odplegacy.org/PDF/ Admin/Long_Range/CONCORD.pdf) on Ocean Riser Drilling posed the question “What role do the lower crust and upper mantle play in the origin of marine magnetic anomalies?” The Initial Science Plan (http:// w w w.odplegacy.org/PDF/Admin/L ong_ Range/IODP_ISP.pdf) for IODP “Initiative: how frequently a ield direction with positive inclination occurs when the core ield is reversed (see igure). For a recording latitude of 6.5º fully 25� of the samples of positive inclination will have been produced by the secular variation during a time that the main ield is of reversed polarity. Inclination is the only way of determining a sample’s magnetic polarity in the absence of horizontal orientation, and an error rate of 25� renders the data relatively useless. It will be very dificult to unscramble the magnetization values gathered at such a place so as to be able to determine the external magnetic signature of the crustal rocks. Even at a recording latitude of 25º the probability is still 5� of confusing reversed with normal polarity. The IODP scientiic advice structure should give serious consideration to choosing drilling sites at higher latitudes, preferably greater than 25º. Alternatively, they should ensure that a proven method of horizontal orientation of cores is available by the time “Mission Moho” starts. weather window. Sites under consideration near San Diego and near Valparaiso would satisfy Dr Harrison’s concerns. - Site 1256D, the “6.5 °N main site” mentioned by Dr Harrison is favored for the near future for reasons including gaining engineering experience in deep gabbro holes and for better predicting the thermal structure, which will be useful even if we eventually choose a site at a higher latitude. - We cannot emphasize enough the importance, for the future of scientiic drilling in the ocean crust, to be able to reorient cores in a geographic reference frame. A Hard Rock Core Orientation (HRCO) system would be the ideal solution, and further development and implementation requires community support. - Measuring the downhole magnetic ield with logging tools does meet some of the objectives that Dr Harrison suggests in choosing a site far from the equator. Remanent magnetic data from samples collected over nearly 40 years of drilling still do not provide an unambiguous solution to the dominant 21st Century Mohole” states that “…the Christopher Harrison, Rosenstiel School of source for lineated magnetic anomalies. This source of marine magnetic anomalies will be Marine and Atmospheric Science (RSMAS), is partly related to the prominent effect of much better understood when a complete University of Miami, 4600 Rickenbacker drilling induced remanence, and every effort section of the lower oceanic crust is available Causeway, Miami, Fla. 33149, U.S.A. to reduce this effect should be encouraged. for analysis”. These suggestions seem to have e-mail: charrison@rsmas.maiami.edu While much can be learned from the magne- been forgotten by the “Mission Moho” group. The only place that crustal magnetization is discussed is in one phrase: “better understand the origin of magnetic anomalies”. No tization of drillcore samples, detailed mag- Response to: Magnetization of the Oceanic Crust netic logging is arguably the best way to establish the relative contributions of the various parts of the crust to the magnetic anoma- B. Ildefonse, et al. mention was made of the desirability of drill- We fully share Dr Harrison’s concerns lies. A reliable gyro-oriented tool should be ing at higher latitudes in order to unscramble about the dificulty in deciphering the mag- designed, developed, and regularly used in the magnetic signal. The main site for drill- netic signal at low latitudes, such as the loca- IODP to achieve this goal. ing lies at 6.5ºN (but was probably formed tion of ODP/IODP Site 1256D , and we thank Benoît closer to the equator). I have recently com- him for bringing everyone’s attention to the Douglas S. Wilson, Jeffrey S. Gee, and the piled a data set of paleomagnetic observations critical need for a method to provide azi- Mission Moho Workshop Steering Committee over the past 5 Ma in which Virtual muthal orientation. Although this topic was (Natsue Geomagnetic Poles from all latitudes were not discussed in the workshop report pub- Donna Blackman, Bob Duncan, Emilie Hooft, used. From this data set it is possible to deter- lished in the March 2007 issue of Scientific Susan Humphris, and Jay Miller) mine, as a function of observation latitude, Drilling, it was extensively discussed at the e-mail: benoit.ildefonse@gm.univ-montp2.fr Ildefonse, Abe, Shoji David Arai, M. Christie, Wolfgan Bach, Scientific Drilling, No. 6, July 2008 71 Schedules IODP - Expedition Schedule http://www.iodp.org/expeditions/ ESO Operations * Platform Dates Port of Origin 1 313 - New Jersey Shallow Shelf MSP May '09–Aug. '09 TBD 2 Great Barrier Reef MSP Sep. '09–Nov. '09 USIO Operations ** Platform Dates Port of Origin 317 - Canterbury Basin JOIDES Resolution 12 Nov. '08–04 Jan. '09 Wellington, New Zealand 318 - Wilkes Land JOIDES Resolution 04 Jan. '09–09 Mar. '09 Wellington, New Zealand 320 - Pacific Equatorial Age Transect (PEAT) JOIDES Resolution 09 Mar. '09–09 May '09 Wellington, New Zealand 321 - PEAT/ Juan de Fuca Remedial Cementing JOIDES Resolution 09 May '09–09 Jul. '09 Honolulu, Hawaii, U.S.A. CDEX Operations *** Platform Dates Port of Origin 319 - NanTroSEIZE — Kumano Basin Riser Chikyu Mar '09 – mid Jun. '09 TBD NanTroSEIZE — Sediment Inputs Chikyu Mid Jun. '09 – late Jul. '09 NanTroSEIZE — Riserless Observatory Casing Chikyu Late Jul. '09 – Aug. '09 3 4 5 35 6 6 6 3 MSP = Mission Specific Platform TBD = to be determined * Dates subject to change pending final platform tenders. ** Dates of expeditions subject to change pending final delivery of vessel from shipyard. *** CDEX schedule subject to final program approval. ICDP 1 22 33 64 75 1 - Project Schedule http://www.icdp-online.org/projects/ ICDP Projects Drilling Dates Location Iceland Deep Drilling Project Jun. '08–'10 Krafla, Iceland Lake El'gygytgyn Drilling Project Apr. '08–May '10 Chukotka, Russia PASADO (Lake Potrok Aike) Sep. to Oct. '08 Patagonia, Argentina New Jersey ** May to Jul. '09 Offshore New Jersey, U.S.A. Lake Van Summer 2009 Anatolia, Turkey **IODP-ICDP joint project All dates are approximate. Schedules are subject to approval. 90º 120º 150º 180º 210º 240º 270º 300º 330º 2 30º 1 60º 4 30º 0º 60º 1 5 30º 6 5 0º 0º 2 -30º -30º 3 3 -60º -60º 4 IODP ICDP 90º 120º 150º 180º 210º 240º 270º 300º 330º 0º 30º