Advance, retreat, and possible collapse of the West Antarctic Ice Sheet as recorded in the Amundsen Sea Embayment: A new IODP proposal

gerhard.kuhn [ at ]


The West Antarctic Ice Sheet (WAIS), which is grounded below present-day sea level and, thus, is highly sensitive to climatic changes, is likely to have had a very dynamic history over the last several million years. WAIS collapse would result in a global sealevel rise of 3-5 m over present levels yet little is known of how it has behaved in the past. Large uncertainties exist regarding the chronology, extent, rates, and spatial and temporal variability of past advances and retreats of the WAIS across the continental shelves, particularly in the Amundsen Sea sector, where no drilling has taken place despite the intense interest in the current and potential behavior of the glaciers feeding into the over-deepened Pine Island Bay. These uncertainties are mainly due to the paucity of data from drill core from this sector. We propose a series of drill cores for the Amundsen Sea Embayment shelf, which is unambiguously fed by the WAIS, where seismic data reveal seaward-dipping sedimentary sequences that are estimated to span the time from the pre-glacial conditions, Miocene or older, to the most recent glacial cycle. Our drilling strategy is to target a transect that includes the oldest sedimentary sequences deposited onto bedrock in the south to the youngest sequences in the north of the western and eastern Amundsen Sea Embayment continental shelf. This transect will yield a detailed history of the glacial cycles in the Pine Island-Amundsen Sea region and allow correlations to the glacial history known from the Ross Sea and to global climate records. In addition, deep-water sites on the continental rise of the embayment are selected for recovering continuous records of glacially transported sediments and the details of climatic and oceanographic changes throughout glacial-interglacial cycles. Because so little is known about the stratigraphy on the Amundsen Sea shelf, new drill core will allow a wide range of questions to be addressed, including: (1) What is the history of advance and retreat of the WAIS in this sector and thus its contribution to past sea-level changes in terms of both rate and magnitude? Have sectors of the marine-based WAIS experienced significant collapses? (2) How does this glacial history correlate with periods of climate warming and changes in ocean circulation? How do warm Circumpolar Deep Water (CDW) incursions onto the continental shelf affect the stability of marine-based ice sheet margins? (3) How did the WAIS behave in the middle Pliocene, the last time Earth’s atmosphere contained more than 400 ppm CO2 and when the Arctic was significantly warmer than today? (4) When did the WAIS first expand onto the ASE continental shelf? Was ice sheet expansion related to uplift in neighboring Marie Byrd Land or related to largescale climate trends?

Item Type
Conference (Talk)
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Primary Topic
Publication Status
Event Details
Antarctic Geologic Drilling Workshop, 07 Nov 2013 - 08 Nov 2013, University of Houston, TX, USA.
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Wellner, J. S. , Gohl, K. , Anderson, J. B. , Bickert, T. , Hillenbrand, C. D. , Konfirst, M. , Kuhn, G. , Salzmann, U. and Uenzelmann-Neben, G. (2013): Advance, retreat, and possible collapse of the West Antarctic Ice Sheet as recorded in the Amundsen Sea Embayment: A new IODP proposal , Antarctic Geologic Drilling Workshop, University of Houston, TX, USA, 7 November 2013 - 8 November 2013 .

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