Late Quaternary Climatic Cycles as Recorded in Sediments from the Antarctic Continental Margin

摘要: To reveal the late Quaternary paleoenvironmental changes at Antarctic continental margin, we test a lithostratigraphy, adjusted to stable isotope record from eastern Weddell Sea. The stratigraphy is used produce stacked sedimentological data set of eleven sediment cores. We derive general model glacio marine sedimentation and East margin during last two climatic cycles (300 kyr).The sedimentary processes considered include biological productivity, ice-rafting, current transport, gravitational downslope transport. These are controlled by complex interaction sea-level paleoceanographic paleoglacial conditions in response global climate local insolation. Sedimentation rates mainly ice-rafting which reflects mass balance behaviour ice sheet. decrease with distance continent interglacial glacial. Highest occur very beginning interglacials, i.e. oxygen events 7.5, 5.5, 1.1, these being up five times higher than glacials.The sediments can be classified into distinct facies correlated different paleoenvironments: glacial terminations (isotope 8.0, 6.0, 2.0), cryosphere adjusts new conditions. rise sea level, destruction shelves, retreat sea-ice recommenced feeding warm North Atlantic Deep Water (NADW) Circumpolar (CDW). During peak periods (at 7.3, 5.5., 1.1), CDW promotes warmer surface waters thus turn controls availability light waters. At thresholds insolation might also influence distribution. Primary productivity bioturbation increase, CCD rises carbonate dissolution occurs slope shallow depth. Ice shelves coastal polynyas favour formation cold saline Shelf (ISW) contributes bottom water formation. transition time stages 7.2-7.0, 5.4-5.0) superimposition both intense reduced currents produces typical lag specific change. With onset 7.0 5.0) sheet expands due lowering extensive glaciations northern Hemisphere. Gravitational transport becomes most active process, transfer deep provided turbidity through canyon systems. maxima between 7.0-6.0, 5.0-2.0) strongly input NADW Southern Ocean favours further advances far beyond shelf break continous ice. Below and/or closed coverage contourites deposited on slope.