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- PublicationRestrictedNeogene tectonic and climatic evolution of the Western Ross Sea, Antarctica — Chronology of events from the AND-1B drill hole(2012-10)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Wilson, G. S.; Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand ;Levy, R. H.; GNS Science, PO Box 30‐368, Lower Hutt, New Zealand ;Naish, T. R.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Powell, R. D.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, USA ;Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Ohneiser, C.; Department of Geology, University of Otago, PO Box 56, Dunedin, New Zealand ;Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Winter, D. M.; ANDRILL Science Management Office, Department of Geosciences, University of Nebraska-Lincoln, Lincoln, NE 68588‐0340, USA ;Cody, R.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Henrys, S.; GNS Science, PO Box 30‐368, Lower Hutt, New Zealand ;Ross, J.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, NM 87801, USA ;Krissek, L.; Byrd Polar Research Centre, The Ohio State University, Columbus, OH 43210, USA ;Niessen, F.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515, Bremerhaven, Germany ;Pompillio, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Scherer, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, USA ;Alloway, B. V.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Barrett, P. J.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Brachfeld, S.; Department of Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043, USA ;Browne, G.; GNS Science, PO Box 30‐368, Lower Hutt, New Zealand ;Carter, L.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Cowan, E.; Department of Geology, Appalachian State University, Boone, NC 28608‐2067, USA ;Crampton, J.; GNS Science, PO Box 30‐368, Lower Hutt, New Zealand ;DeConto, R. M.; Department of Geosciences, University of Massachusetts, Amherst, MA 01003‐9297, USA ;Dunbar, G.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Dunbar, N.; Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand ;Dunbar, R.; Department of Environmental Earth System Sciences, School of Earth Sciences, Stanford University, Stanford, CA 94305, USA ;von Eynatten, H.; Department of Sedimentology and Environmental Geology, Geoscience Center Göttingen (GZG), Goldschmidtstrasse 3, Göttingen, Germany ;Gebhardt, C.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515, Bremerhaven, Germany ;Giorgetti, G.; Dipartimento di Scienze della Terra, Universita di Sienna, Via Laterina 8, I-53100, Sienna, Italy ;Graham, I.; GNS Science, PO Box 30‐368, Lower Hutt, New Zealand ;Hannah, M.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Hansaraj, D.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Harwood, D. M.; ANDRILL Science Management Office, Department of Geosciences, University of Nebraska-Lincoln, Lincoln, NE 68588‐0340, USA ;Hinnov, L.; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA ;Jarrard, R. D.; Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112, USA ;Joseph, L.; Environmental Studies Program, Ursinus College, Collegeville, PA 19426, USA ;Kominz, M.; Department of Geology, Western Michigan University, Kalamazoo, MI 49008, USA ;Kuhn, G.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515, Bremerhaven, Germany ;Kyle, P.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, NM 87801, USA ;Läufer, A.; Federal Institute for Geosciences & Natural Resources, BGR, Stilleweg 2, D-30655 Hannover, Germany ;McIntosh, W. C.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, NM 87801, USA ;McKay, R.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, New Zealand ;Maffioli, P.; Università Milano-Bicocca, Dipartimento di Scienze Geologiche e Geotecnologie, Piazza della Scienza 4, I-20126 Milano, Italy ;Magens, D.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515, Bremerhaven, Germany ;Millan, C.; Byrd Polar Research Centre, The Ohio State University, Columbus, OH 43210, USA ;Monien, D.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515, Bremerhaven, Germany ;Morin, R.; US Geological Survey, Mail Stop 403, Denver Federal Center, Denver, CO 80225, USA ;Paulsen, T.; Department of Geology, University of Wisconsin, Oshkosh, 800 WI 54901, USA ;Persico, D.; Departimento di Scienze della Terra, Universita di Parma, Parco Aeres delle Scienze, 157 Parma, Italy ;Pollard, D.; Earth and Environmental Systems Institute, 2217 Earth-Engineering Science Bldg, University Park, PA 16802, USA ;Raine, J. I.; GNS Science, PO Box 30‐368, Lower Hutt, New Zealand ;Riesselman, C.; Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand ;Sandroni, S.; Dipartimento di Scienze della Terra, Universita di Sienna, Via Laterina 8, I-53100, Sienna, Italy ;Schmitt, D.; Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand ;Sjunneskog, C.; Antarctic Marine Geology Research Facility, Department of Geology, Florida State University, Tallahassee, FL 32306, USA ;Strong, C. P.; GNS Science, PO Box 30‐368, Lower Hutt, New Zealand ;Talarico, F.; Dipartimento di Scienze della Terra, Universita di Sienna, Via Laterina 8, I-53100, Sienna, Italy ;Taviani, M.; CNR, ISMAR — Bologna, Via Gobetti 101, I-40129 Bologna, Italy ;Villa, G.; Departimento di Scienze della Terra, Universita di Parma, Parco Aeres delle Scienze, 157 Parma, Italy ;Vogel, S.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, USA ;Wilch, T.; Albion College, Department of Geology, Albion, MI 49224, USA ;Williams, T.; Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY 10964, USA ;Wilson, T. J.; Byrd Polar Research Centre, The Ohio State University, Columbus, OH 43210, USA ;Wise, S.; Antarctic Marine Geology Research Facility, Department of Geology, Florida State University, Tallahassee, FL 32306, USA; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Stratigraphic drilling from the McMurdo Ice Shelf in the 2006/2007 austral summer recovered a 1284.87 m sedimentary succession from beneath the sea floor. Key age data for the core include magnetic polarity stratigraphy for the entire succession, diatom biostratigraphy for the upper 600 m and 40Ar/39Ar ages for in-situ volcanic deposits as well as reworked volcanic clasts. A vertical seismic profile for the drill hole allows correlation between the drill hole and a regional seismic network and inference of age constraint by correlation with well‐dated regional volcanic events through direct recognition of interlayered volcanic deposits as well as by inference from flexural loading of pre‐existing strata. The combined age model implies relatively rapid (1 m/2–5 ky) accumulation of sediment punctuated by hiatuses, which account for approximately 50% of the record. Three of the longer hiatuses coincide with basin‐wide seismic reflectors and, along with two thick volcanic intervals, they subdivide the succession into seven chronostratigraphic intervals with characteristic facies: 1. The base of the cored succession (1275–1220 mbsf) comprises middle Miocene volcaniclastic sandstone dated at approx 13.5 Ma by several reworked volcanic clasts; 2. A late-Miocene sub-polar orbitally controlled glacial–interglacial succession (1220–760 mbsf) bounded by two unconformities correlated with basin‐wide reflectors associated with early development of the terror rift; 3. A late Miocene volcanigenic succession (760–596 mbsf) terminating with a ~1 my hiatus at 596.35 mbsf which spans the Miocene–Pliocene boundary and is not recognised in regional seismic data; 4. An early Pliocene obliquity-controlled alternating diamictite and diatomite glacial–interglacial succession(590–440 mbsf), separated from; 5. A late Pliocene obliquity-controlled alternating diamictite and diatomite glacial–interglacial succession (440–150 mbsf) by a 750 ky unconformity interpreted to represent a major sequence boundary at other locations; 6. An early Pleistocene interbedded volcanic, diamictite and diatomite succession (150–80 mbsf), and; 7. A late Pleistocene glacigene succession (80–0 mbsf) comprising diamictite dominated sedimentary cycles deposited in a polar environment.486 63 - PublicationRestrictedObliquity-paced Pliocene West Antarctic ice sheet oscillations(2009-03-19)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Naish, T.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand ;Powell, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA. ;Levy, R.; ANDRILL Science Management Office, Department of Geosciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0340, USA ;Wilson, G.; University of Otago, Department of Geology, PO Box 56, Leith Street, Dunedin, Otago 9001, New Zealand ;Scherer, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA. ;Talarico, F.; Universita` di Siena, Dipartimento di Scienze delle Terra, Via Laterina 8, I-53100 Siena, Italy ;Krissek, L.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA ;Niessen, F.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany ;Pompilio, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Wilson, T.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA ;Carter, L.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand ;DeConto, R.; Department of Geosciences, 233 Morrell Science Centre, University of Massachusetts, Amherst, Massachusetts 01003-9297, USA ;Huybers, P.; Department of Earth and Planetary Sciences, Harvard University, Massachusetts 02138, USA ;Mckay, R.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand ;Pollard, D.; Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA ;Ross, J.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, New Mexico 87801, USA ;Winter, D.; ANDRILL Science Management Office, Department of Geosciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0340, USA ;Barrett, P.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand ;Browne, G.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand ;Cody, R.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand ;Cowan, E.; Department of Geology, Appalachian State University, ASU Box 32067, Boone, North Carolina 28608-2067, USA ;Crampton, J.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand ;Dunbar, G.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand ;Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Gebhardt, C.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany ;Graham, I.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand ;Hannah, M.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand ;Hansaraj, D.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand ;Harwood, D.; ANDRILL Science Management Office, Department of Geosciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0340, USA ;Helling, D.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany ;Henrys, S.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand ;Hinnov, L.; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA ;Kuhn, G.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany ;Kyle, P.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, New Mexico 87801, USA ;Laüfer, A.; Federal Institute of Geosciences & Natural Resources, BGR, Stilleweg 2, D-30655 Hannover, Germany ;Maffioli, P.; Universita` Milano-Bicocca, Dipartimento di Scienze Geologiche e Geotecnologie, Piazza della Scienza 4, I-20126 Milano, Italy ;Magens, D.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany ;Mandernack, K.; Colorado School of Mines, Department of Chemistry & Geochemistry, 1500 Illinois Street, Golden, Colorado 80401, USA ;McIntosh, W.; New Mexico Institute of Mining & Technology, Earth & Environmental Sciences, Socorro, New Mexico 87801, USA ;Millan, C.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA ;Morin, R.; US Geological Survey, Mail Stop 403, Denver Federal Center, Denver, Colorado 80225, USA ;Ohneiser, C.; University of Otago, Department of Geology, PO Box 56, Leith Street, Dunedin, Otago 9001, New Zealand ;Paulsen, T.; University of Wisconsin-Oshkosh, Department of Geology, 800 Algoma Boulevard, Oshkosh, Wisconsin 54901, USA ;Persico, D.; Dipartimento di Scienze della Terra, Universita` degli Studi di Parma, Via Usberti 157/A, I-43100 Parma, Italy ;Raine, I.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand ;Reed, J.; CHRONOS, Iowa State University, Department of Geological & Atmospheric Sciences, 275 Science I, Ames, Iowa 50011-3212, USA ;Riesselman, C.; Department of Geological and Environmental Sciences, School of Earth Sciences, Stanford University, Stanford, California 94305, USA ;Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Schmitt, D.; Department of Physics, Mailstop #615, University of Alberta, Edmonton, Alberta T6G 2G7, Canada ;Sjunneskog, C.; Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA ;Strong, P.; GNS Science, 1 Fairway Drive, PO Box 30-368, Lower Hutt 5040, New Zealand ;Taviani, M.; CNR, ISMAR – Bologna, Via Gobetti 101, I-40129 Bologna, Italy ;Vogel, S.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA. ;Wilch, T.; Albion College, Department of Geology, Albion, Michigan 49224, USA ;Williams, T.; Columbia University, Lamont-Doherty Earth Observatory, Palisades, New York 10964, USA; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Thirty years after oxygen isotope records frommicrofossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth’s orbital geometry control the ice ages1, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles2. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the ‘warmer-than- present’ early-Pliocene epoch (̃5–3Myr ago) is needed to better constrain the possible range of ice-sheet behaviour in the context of future global warming3. Here we present a marine glacial record from the upper 600 m of theAND-1B sediment core recovered from beneath the northwest part of the Ross ice shelf by the ANDRILL programme and demonstrate well-dated, ̃40-kyr cyclic variations in ice-sheet extent linked to cycles in insolation influenced by changes in the Earth’s axial tilt (obliquity) during the Pliocene. Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to ̃3 C warmer than today4 and atmospheric CO2 concentration was as high as ̃400 p.p.m.v. (refs 5, 6). The evidence is consistent with a new ice-sheet/ice-shelf model7 that simulates fluctuations in Antarctic ice volume of up to + 7 m in equivalent sea level associated with the loss of the WAIS and up to +3 m in equivalent sea level from the EastAntarctic ice sheet, in response to ocean-induced melting paced by obliquity.During interglacial times, diatomaceous sediments indicate high surface-water productivity, minimal summer sea ice and air temperatures above freezing, suggesting an additional influence of surface melt8 under conditions of elevated CO2.525 98 - PublicationRestrictedPreliminary Integrated Chronostratigraphy of the AND-1B Core, ANDRILL McMurdo Ice Shelf Project, Antarctica(2007)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;the ANDRILL-MIS Science Team ;Wilson, G.; Department of Geology, University of Otago, PO Box 56, Dunedin - New Zealand ;Levy, R.; ANDRILL Science Management Office, 126 Bessey Hall, University of Nebraska - Lincoln, Lincoln, NE 68588-0341 - USA ;Browne, G.; GNS Science, PO Box 30368, Lower Hutt - New Zealand ;Cody, R.; ANDRILL Science Management Office, 126 Bessey Hall, University of Nebraska - Lincoln, Lincoln, NE 68588-0341 - USA and GNS Science, PO Box 30368, Lower Hutt - New Zealand ;Dunbar, N.; Earth and Environmental Science Department, New Mexico Institute of Technology, 801 Leroy Place, Socorro, NM 87801 - USA ;Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Herrys, S.; GNS Science, PO Box 30368, Lower Hutt - New Zealand ;Graham, I.; GNS Science, PO Box 30368, Lower Hutt - New Zealand ;McIntosh, W.; Earth and Environmental Science Department, New Mexico Institute of Technology, 801 Leroy Place, Socorro, NM 87801 - USA ;McKay, R.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington - New Zealand ;Naish, T.; GNS Science, PO Box 30368, Lower Hutt - New Zealand and Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington - New Zealand ;Ohneiser, C.; Department of Geology, University of Otago, PO Box 56, Dunedin - New Zealand ;Powell, R.; Department of Geology and Environmental Geosciences, 312 Davis Hall, Normal Road, Northern Illinois University, De Kalb, IL 60115-2854 - USA ;Ross, J.; Earth and Environmental Science Department, New Mexico Institute of Technology, 801 Leroy Place, Socorro, NM 87801 - USA ;Sagnotti, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Scherer, R.; Department of Geology and Environmental Geosciences, 312 Davis Hall, Normal Road, Northern Illinois University, De Kalb, IL 60115-2854 - USA ;Sjunneskog, C.; Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803 - USA ;Strong, C. P.; GNS Science, PO Box 30368, Lower Hutt - New Zealand ;Taviani, M.; Istituto di Geologia Marina, CNR, Via Gobetti 101, I-40129 Bologna - Italy ;Winter, D.; Department of Geosciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0340 - USA ;the ANDRILL-MIS Science Team; ANDRILL; ; ; ; ;; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Chronostratigraphic data available for the preliminary age model for the upper 700 m for the AND-1B drill core include diatom biostratigraphy, magnetostratigraphy, 40Ar/39Ar ages on volcanic material, 87Sr/86Sr ages on calcareous fossil material, and surfaces of erosion identified from physical appearance and facies relationships recognised in the AND-1B drill core. The available age data allow a relatively well-constrained age model to be constructed for the upper 700 m of the drill core. Available diatom biostratigraphic constraints and 40Ar/39Ar ages allow a unique correlation of ~70% of the AND-1B magnetic polarity stratigraphy with the Geomagnetic Polar Time Scale (GPTS). Unique correlation is not possible in several coarse diamictite intervals with closely spaced glacial surfaces of erosion and sparse microflora. However, the age model indicates relatively rapid (up to 1 m/k.y.) and continuous accumulation of intervening finer grained diatomaceous intervals punctuated by several half- to million-years hiatuses representing more than half of the last 7 m.y. in the AND-1B record. The mid- to late Pleistocene is represented by superimposed diamictite units separated from upper Pliocene alternating diamictites/diatomites by a ~1 m.y. hiatus co-incident with a regionally correlated seismic reflection surface. A c. 100 m-thick diatomite represents a significant portion of the early Pliocene record in the AND-1B drill core. Strata below ~620 m are late Miocene in age; however, biostratigraphic constraints are absent below 586 m and correlation with the GPTS is relatively unconstrained. At the the of writing, the only chronostratigraphic data available below 700 mbsf include three 40Ar/39Ar ages on volcanic clasts from near 1280 mbsf affording a maximum depositional age of 13.57 Ma for the base of the AND-1B drill core.187 27