Biostratigraphic constraints on the Plio-Pleistocene chronology of West Antarctic Ice Sheet grounding events in North Basin
Abstract
Several seismic units interpreted to represent discrete West Antarctic Ice Sheet (WAIS) grounding events are exposed at the seafloor in North Basin, Ross Sea. The chronology of these grounding events was investigated using diatom biostratigraphy from piston cores at locations where these seismic units outcrop. The piston-core data shows that the North Basin section is of late Pliocene to late Pleistocene age, and represents a period of Antarctic glacial history that has not previously been recovered in detail. Although the utility of diatom biostratigraphy is somewhat limited by the absence of open ocean species that define the biostratigraphic zones, the careful selection of piston cores within a seismic framework has yielded samples that clearly show a chronostratigraphic succession. Sediment draping Unconformity 10 is of late Pliocene age, ca 2.1-2.0 Ma. The drape overlying Unconformities 7 and 3 show consecutive younger ages 1.5-0.9 Ma and 0.7-0.07 Ma respectively. Coeval interglacial sediments at AND-1B demonstrate that major expansions of the WAIS to North Basin were followed by major retreat of grounded and floating ice to the south of Ross Island.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMPP43A1549B
- Keywords:
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- 0726 CRYOSPHERE / Ice sheets