@article{8e42a5e89e9847ad92b2fcdf43757c60,
title = "Episodes of Early Pleistocene West Antarctic Ice Sheet Retreat Recorded by Iceberg Alley Sediments",
abstract = "Ice loss in the Southern Hemisphere has been greatest over the past 30 years in West Antarctica. The high sensitivity of this region to climate change has motivated geologists to examine marine sedimentary records for evidence of past episodes of West Antarctic Ice Sheet (WAIS) instability. Sediments accumulating in the Scotia Sea are useful to examine for this purpose because they receive iceberg-rafted debris (IBRD) sourced from the Pacific- and Atlantic-facing sectors of West Antarctica. Here we report on the sedimentology and provenance of the oldest of three cm-scale coarse-grained layers recovered from this sea at International Ocean Discovery Program Site U1538. These layers are preserved in opal-rich sediments deposited ∼1.2 Ma during a relatively warm regional climate. Our microCT-based analysis of the layer's in-situ fabric confirms its ice-rafted origin. We further infer that it is the product of an intense but short-lived episode of IBRD deposition. Based on the petrography of its sand fraction and the Phanerozoic 40Ar/39Ar ages of hornblende and mica it contains, we conclude that the IBRD it contains was likely sourced from the Weddell Sea and/or Amundsen Sea embayment(s) of West Antarctica. We attribute the high concentrations of IBRD in these layers to “dirty” icebergs calved from the WAIS following its retreat inland from its modern grounding line. These layers also sit at the top of a ∼366-m thick Pliocene and early Pleistocene sequence that is much more dropstone-rich than its overlying sediments. We speculate this fact may reflect that WAIS mass-balance was highly dynamic during the ∼41-kyr (inter)glacial world.",
keywords = "Antarctic Ice Sheet, Ar-Ar, deglaciation, ice rafted debris, ice-sheet retreat, iceberg alley, IODP, IODP expedition 382, MicroCT, pirie basin, provenance, QEMSCAN, scotia sea, SEM, southern ocean, West Antarctic Ice Sheet",
author = "Ian Bailey and Sidney Hemming and Reilly, {Brendan T.} and Gavyn Rollinson and Trevor Williams and Weber, {Michael E.} and Raymo, {Maureen E.} and Peck, {Victoria L.} and Ronge, {Thomas A.} and Stefanie Brachfeld and Suzanne O'Connell and Lisa Tauxe and Warnock, {Jonathan P.} and Linda Armbrecht and Cardillo, {Fabricio G.} and Zhiheng Du and Gerson Fauth and Marga Garcia and Anna Glueder and Michelle Guitard and Marcus Gutjahr and Iv{\'a}n Hern{\'a}ndez-Almeida and Hoem, {Frida S.} and Hwang, {Ji Hwan} and Mutsumi Iizuka and Yuji Kato and Bridget Kenlee and Martos, {Yasmina M.} and P{\'e}rez, {Lara F.} and Osamu Seki and Shubham Tripathi and Xufeng Zheng",
note = "Funding Information: This research used samples provided by International Ocean Discovery Program (IODP), which is sponsored by the US National Science Foundation and participating countries under management of Joint Oceanographic Institutions, Inc. We thank H. Kuhlmann and A. Wuelbers for help with sampling. This work was made possible by the use of the Oregon State University microCT facility ( microct.oregonstate.edu ), a user facility developed with support from the Major Research Instrumentation Program of NSF's Earth Science (EAR) directorate under award #1531316. We also thank Dorthe Wildenschild and Douglas Meisenheimer for help with the collection and analysis of the microCT data. We thank the editor (Matthew Huber), Tim Naish and two other anonymous reviewers for constructive feedback that helped to improve the final version of this manuscript. I. Bailey, S. Hemming, B. T. Reilly, T. Williams, J. P. Warnock, S. O'Connell, S. Brachfeld and L. Tauxe acknowledge support from a National Science Foundation (NSF) award (OPP 2114763, 2114764, 2114769, 2114777, 2114786, 2114768). US participants on Expedition 382 acknowledge support from the US Science Support Program and Columbia University (NSF award OCE 1450528). I. Bailey and L. F. P{\'e}rez. also thank the Natural Environmental Research Council (NERC) for financial support for their participation in IODP Exp. 382 and for I. Bailey{\textquoteright}s subsequent research on the materials examined for this study (UK IODP Grant NE/T006609/1 and NE/T013648/1, respectively). L. F. P{\'e}rez also received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk{\l}odowska‐Curie grant (agreement No. 792773). M. E. Weber received funding for this research from the Deutsche Forschungsgemeinschaft (DFG–Priority Programme 527, Grant We2039/17‐1). Y. M. Martos acknowledges the support of NASA (award number 80GSFC21M0002). L. Armbrecht was supported by the Australian and New Zealand International Ocean Discovery Program Consortium (ANZIC), and an Australian Research Council (ARC) Discovery Early Career Researcher (DECRA) Fellowship (DE210100929). M. Garcia acknowledges the funding of projects CTM2017‐89711‐C2‐1‐P and CGL2015‐74216‐JIN by the Spanish MINECO and support from the SCAR Scientific Research Programme PAIS. Funding Information: This research used samples provided by International Ocean Discovery Program (IODP), which is sponsored by the US National Science Foundation and participating countries under management of Joint Oceanographic Institutions, Inc. We thank H. Kuhlmann and A. Wuelbers for help with sampling. This work was made possible by the use of the Oregon State University microCT facility (microct.oregonstate.edu), a user facility developed with support from the Major Research Instrumentation Program of NSF's Earth Science (EAR) directorate under award #1531316. We also thank Dorthe Wildenschild and Douglas Meisenheimer for help with the collection and analysis of the microCT data. We thank the editor (Matthew Huber), Tim Naish and two other anonymous reviewers for constructive feedback that helped to improve the final version of this manuscript. I. Bailey, S. Hemming, B. T. Reilly, T. Williams, J. P. Warnock, S. O'Connell, S. Brachfeld and L. Tauxe acknowledge support from a National Science Foundation (NSF) award (OPP 2114763, 2114764, 2114769, 2114777, 2114786, 2114768). US participants on Expedition 382 acknowledge support from the US Science Support Program and Columbia University (NSF award OCE 1450528). I. Bailey and L. F. P{\'e}rez. also thank the Natural Environmental Research Council (NERC) for financial support for their participation in IODP Exp. 382 and for I. Bailey{\textquoteright}s subsequent research on the materials examined for this study (UK IODP Grant NE/T006609/1 and NE/T013648/1, respectively). L. F. P{\'e}rez also received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk{\l}odowska-Curie grant (agreement No. 792773). M. E. Weber received funding for this research from the Deutsche Forschungsgemeinschaft (DFG–Priority Programme 527, Grant We2039/17-1). Y. M. Martos acknowledges the support of NASA (award number 80GSFC21M0002). L. Armbrecht was supported by the Australian and New Zealand International Ocean Discovery Program Consortium (ANZIC), and an Australian Research Council (ARC) Discovery Early Career Researcher (DECRA) Fellowship (DE210100929). M. Garcia acknowledges the funding of projects CTM2017-89711-C2-1-P and CGL2015-74216-JIN by the Spanish MINECO and support from the SCAR Scientific Research Programme PAIS. Publisher Copyright: {\textcopyright} 2022. The Authors.",
year = "2022",
month = jul,
doi = "10.1029/2022PA004433",
language = "English",
volume = "37",
journal = "Paleoceanography and Paleoclimatology",
issn = "2572-4517",
publisher = "John Wiley and Sons Inc.",
number = "7",
}
