Seismic stratigraphic record of the Amundsen Sea Embayment shelf from pre-glacial to recent times: Evidence for a dynamic West Antarctic Ice Sheet

• Published in: Marine Geology
• Main Authors: Gohl, Karsten, Uenzelmann-Neben, Gabriele, Larter, Robert D., Hillenbrand, Claus-Dieter, Hochmuth, Katharina, Kalberg, Thomas, Weigelt, Estella, Davy, Bryan, Kuhn, Gerhard, Nitsche, Frank O.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: Antarctic; The Antarctic; West Antarctica; Amundsen Sea; West Antarctic Ice Sheet; Antarc*; Antarctica; Ice Sheet
• Online Access: http://nora.nerc.ac.uk/id/eprint/502396/; https://nora.nerc.ac.uk/id/eprint/502396/1/1-s2.0-S0025322713001321-main.pdf; https://doi.org/10.1016/j.margeo.2013.06.011

Studies of the sedimentary architecture and characteristics of the Antarctic continental margin provide clues about past ice sheet advance-retreat cycles and help improve constraints for paleo-ice dynamic models since early glacial periods. A first seismostratigraphic analysis of the Amundsen Sea Embayment shelf and slope of West Antarctica reveals insights into the structural architecture of the continental margin and shows stages of sediment deposition, erosion and transport reflecting the history from pre-glacial times to early glaciation and to the late Pleistocene glacial-interglacial cycles. The shelf geometry consists of a large pre- and syn-rift basin in the middle shelf region between basement cropping out on the inner shelf and buried basement ridge and highs on the outer shelf. A subordinate basin within the large basin on the mid-shelf may be associated with motion along an early West Antarctic Rift System branch. At least 4 km of pre-glacial strata have been eroded from the present inner shelf and coastal hinterland by glacial processes. Six major sedimentary units (ASS-1 to ASS-6) separated by five major erosional unconformities (ASS-u1 to ASS-u5) are distinguished from bottom to top. Unconformity ASS-u4 results from a major truncational event by glacial advance to the middle and outer shelf, which was followed by several episodes of glacial advance and retreat as observed from smaller-scale truncational unconformities within the units above ASS-u4. Some of the eroded sediments were deposited as a progradional wedge that extends the outer shelf by 25 to 65 km oceanward of the pre-glacial shelf-break. We compare the observed seismic characteristics with those of other Antarctic shelf sequences and assign an Early Cretaceous age to bottom sedimentary unit ASS-1, a Late Cretaceous to Oligocene age to unit ASS-2, an Early to Mid-Miocene age to unit ASS-3, a Mid-Miocene age to unit ASS-4, a Late Miocene to Early Pliocene age to unit ASS-5, and a Pliocene to Pleistocene age to the top unit ASS-6. Buried ...