Late Pleistocene-Holocene marine conditions in the Ross Sea, Antarctica: evidence from the diatom record

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Abstract
Statistical analyses of diatom assemblages from radiocarbon-dated sediment cores were used to reconstruct changing palaeoceanographic conditions in the western and west-central Ross Sea, Antarctica, from. c.12 14C kyr BP to the present. Data from three Kasten cores support a north-to-south time-transgressive glacial/interglacial transition. Assemblages at the base of each core suggest that glacial processes affecting frustule preservation were significant during the late Pleistocene. Increasing biogenic silic and decreasing per centages of reworked species suggest that upper water-column productivity, instead of preservational processes, increasingly dominates diatom assemblages during grounding-line recession (c.12to c.6 14C kyr BP). A warm ing during the middle to late Holocene (c.6to c.3 14C kyr BP) may have resulted in: (a) spring sea ice melting prior to the annual inception of the Ross Sea polynya in the west-central Ross Sea, and (b) increased plateletice delivery due to increased melting beneath the ice sheet in coastal areas. An increasingly cooler late Holocene (c.3 14C kyr BP to the present) may have resulted in: (a) decreased sea-ice melting prior to physical disinte gration of the annual sea-ice cover by spring inception of Ross-Sea-polynya winds in the west-central Ross Sea, and (b) decreased platelet-ice delivery in coastal areas.