Dating glacimarine sediments from the continental shelf in the Amundsen Sea using a multi-tool box: Implications for West Antarctic ice-sheet extent and retreat during the last glacial cycle
Claus-Dieter Hillenbrand1, James Smith1, Johann P Klages2, Gerhard Kuhn3, Barbara Maher4, Steven Moreton5, Lukas Wacker6, Thomas Frederichs7, Steffen Wiers8, Patrycja Jernas9, John B Anderson10, Werner U Ehrmann11, Alastair GC Graham12, Karsten Gohl13 and Robert D Larter14, (1)British Antarctic Survey, Cambridge, United Kingdom, (2)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Marine Geosciences, Bremerhaven, Germany, (3)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research (AWI), Bremerhaven, Germany, (4)University of Lancaster, Lancaster, United Kingdom, (5)NERC Radiocarbon Facility, East Kilbride, United Kingdom, (6)ETH Zurich, Dept. of Ion Beam Physics, Zurich, Switzerland, (7)University of Bremen, Department of Geosciences, Bremen, Germany, (8)Uppsala University, Department of Earth Sciences, Uppsala, Sweden, (9)University of Tromsø, Department of Geology, Tromsø, Norway, (10)Rice University, Department of Earth Science, Houston, TX, United States, (11)Inst fuer Geophysik & Geologie, Leipzig, Germany, (12)University of South Florida St. Petersburg, College of Marine Science, St Petersburg, United States, (13)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany, (14)NERC British Antarctic Survey, Cambridge, United Kingdom
Abstract:
Satellite data and in-situ measurements show that today considerable mass loss is occurring from the Amundsen Sea sector of the West Antarctic Ice Sheet (WAIS). The observational record only spans the past four decades, and until recently the long-term context of the current deglaciation was poorly constrained. This information is, however, crucial for understanding WAIS dynamics, evaluating the role of forcing mechanisms for ice-sheet melting, and testing and calibrating ice-sheet models that attempt to predict future WAIS behavior and its impact on global sea level.
Over the past decade several multinational marine expeditions and terrestrial fieldwork campaigns have targeted the Amundsen Sea shelf and its hinterland to reconstruct the WAIS configuration during the Last Glacial Maximum (LGM) and its subsequent deglacial history. The resulting studies succeeded in shedding light on the maximum WAIS extent at the LGM and the style, pattern and speed of its retreat and thinning thereafter. Despite this progress, however, significant uncertainties and discrepancies between marine and terrestrial reconstructions remain, which may arise from difficulties in dating sediment cores from the Antarctic shelf, especially their deglacial sections. Resolving these issues is crucial for understanding the WAIS’ contribution to post-LGM sea-level rise, its sensitivity to different forcing mechanisms and its future evolution. Here we present chronological constraints on WAIS advance in the Amundsen Sea and its retreat from ~20 ka BP into the Holocene that were obtained by various techniques, such as 14C dating of large (~10 mg) and small (<<1 mg) sample aliquots of calcareous microfossils, 14C dating of acid-insoluble organic matter combusted at low (300 °C) and high (800 °C) temperatures and dating of sediment cores by using geomagnetic paleointensity. We will compare the different age constraints and discuss their reliability, applicability and implications for WAIS history.
