LATE QUATERNARY TERRIGENOUS DEPOSITS FROM CORE P31 ON THE CHUKCHI PLATEAU OF WESTERN ARCTIC OCEAN AND THEIR PALEOCEANOGRAPHIC AND PALEOCLIMATIC IMPLICATIONS

Terrigenous components in the core P31 from the Chukchi Plateau, western Arctic Ocean, have been investigated to reconstruct source regions and related climate changes. Together with AMS¹⁴C dating, the stratigraphy of the core was established by a combination of variations of lithological features, color cycles, XRF scanned elements content, foraminifera abundance, Ice Rafted Detritus (IRD,>250 μm and>154 μm)events and grain size components. The Core P31 extends back to the Marine Isotope Stage (MIS) 3. A total of five IRD events were distinguished during the late MIS 1, MIS 2 and early to mid MIS 3. These IRD, transported by sea ice and icebergs, and brought to the Chukchi Plateau, by the Beaufort Gyre, might be exported from the M'Clure Strait Ice Stream, Canadian Arctic Archipelago. They are indicators of the collapse events of North American Ice Sheet (NAIS) and the evolutionary history of the Beaufort Gyre since MIS 3. Grain size components changes show that the sand components, which correspond to the high IRD size fraction, might be transported by icebergs; but the silt components might be mainly transported by sea ice, and the clay component was probably mainly carried by the Beaufort Gyre. The variation of two sensitive components (5-13 μm and 110-176 μm) present clear symmetric distribution, the coarser component corresponds to the IRD, and the finer may indicate the source region and the influence of deposition. During MIS 3, MIS 2 and MIS 1, the sedimentation rates of core P31 are 2.2 cm/ka, 0.16 cm/ka and 1.6 cm/ka, respectively. The average sedimentation rate is about 1.2 cm/ka. The overall picture of the western Arctic Ocean shows high sedimentation rates in the ice edge, and low sedimentation rates in areas with permanent sea ice cover. High sedimentation rates occur in areas of shallow water depth, and close to the terrigenous source regions, and low sedimentation rates in the high latitude area of Mendeleev-alpha ridge and Canada Basin area.