Late glacial to Holocene climatic and oceanogrpahic record of sediment facies from the South Scotia Sea off the northern Antarctic Peninsula

Abstract

Two gravity cores were collected from the South Scotia Sea during the 02/03 KARP (Korea Antarctic Research Program) expeditions to determine the late Quaternary climatic and oceanographic history of the area. Sedimentological, geochemical and micropaleontological analyses combined with AMS 14C determination represent the most detailed record of late Pleistocene climatic/oceanographic change, to date in Antarctica. During the Last Glacial Maximum, the South Scotia Ocean received large amounts of sorted terrigenous sediments and some of the reworked diatom fossils emplaced by bottom currents from an extensively glaciated Weddell Sea continental margin. Drifting icebergs calved from the glacial fronts have dispersed glacial dropstones over a broad area of the study area. The bottom current deposits in glacial phase comprise two sedimentary units: (1) bioturbated gravelly sandy mud (Facies I), formed by sluggish bottom current caused by reduced dense water production originated from the ice sheet on the Weddell shelf, (2) indistinctly layered diatomaceous mud as shown by TOC highs in the Facies I, deposited by sporadic bottom currents caused by intensified sea-ice formation in polynya during the glacial stage. The Last Glacial Maximum is characterized by greater and long sea-ice coverage and a restricted Weddell/Scotia summer communication, as evidenced by a relative decrease in percentage Thalssiosira antarctica and Chaetoceros resting spores, which are more abundant close to the Weddell Ice Shelf. Deglaciation in the South Scotia Sea was dated from about 12,500 14C yr BP until at least 8,700 14C yr BP, with increasing TOC, diatom abundance, and decreasing MS value, sand content up core. At this time, subglacial meltwater streams began to emanate from the Weddell Ice Sheet with peak of ice-rafting. Sediment-laden turbid plumes from melting glacier and deglaciated Weddell shelf have probably caused high influx of fine suspended sediments into the realm of contour curren