Ice events along the East Siberian continental margin during the last two glaciations: Evidence from clay minerals

Abstract

A large ice sheet or ice shelf may have developed repeatedly along the East Siberian continental margin since the Middle Pleistocene. In combination with ice-rafted debris, major elements, and foraminifera, clay mineral records from four gravity sediment cores are used to trace ice events along the East Siberian continental margin during the last two glaciations. The clay mineral assemblages show a strong link to the extent of the East Siberian ice sheet (ESIS) rather than the ice shelf or icebergs sourced from the Canadian Arctic. During the last two glaciations, illite-rich sediment from East Siberia was transported mainly toward the deep basin, whereas kaolinite-rich sediment from the Canadian Arctic was mostly blocked from the East Siberian continental margin. We speculate that during marine isotope stage 2 (MIS2), the southern Mendeleev Ridge, Chukchi Basin, and Chukchi Rise may have been covered by an ESIS-extended ice shelf; however, the Chukchi Plateau and Northwind Ridge were dominated by a Laurentide-sourced ice shelf. During MIS4, the ESIS may have undergone a marked expansion, with an extended ice shelf occupying all of the Chukchi Plateau and Northwind Ridge, thereby restricting iceberg discharge from other ice sheets.