CENTRAL ARCTIC SURFACE OCEAN ENVIRONMENT DURING THE PAST 80,000 YEARS

Stable oxygen and-carbon isotope and sedimentological-paleontological investigations supported by accelerator mass spectrometry C-14 datings were carried out on cores from north of 85 degrees N in the eastern c entral Arctic Ocean. Significant changes in accumulation rates, proven ance of ice-rafted debris (IRD), and planktic productivity over the pa st 80,000 years are documented. During peak glacials, i.e., oxygen iso tope stages 4 and 2, the Arctic Ocean was covered by sea ice with decr eased seasonal variation, limiting planktic productivity and bulk sedi mentation rates. In early stage 3 and during Termination I, major degl aciations of the circum-Arctic regions caused lowered salinities and p oor oxygenation of central Arctic surface waters. A meltwater spike an d an associated IRD peak dated to similar to 14-12 C-14 ka can be trac ed over the southern Eurasian Basin of the Arctic Ocean. This event wa s associated with the early and rapid deglaciation of the marine-based Barents Sea Ice Sheet. A separate Termination Ib meltwater event is m ost conspicuous in the central Arctic and is associated with character istic dolomitic carbonate IRD. This lithology suggests an origin of gl acial ice from northern Canada and northern Greenland where lower Pale ozoic platform carbonates crop extensively out.