"BACK-ARC" MARINE ICE SHEET IN THE SEA OF OKHOTSK

Abstract

Geomorphologic, marine geological, and paleoclimatic evidence, along with modeling results, indicate that, during the Late Pleistocene, the Sea of Okhotsk was glaciated by a "back-arc" marine ice-sheet, which was a continuous spillover of glaciation from the highlands of Northeast Siberia, buttressed by a submarine ridge of the Kurile Island Arc. That marine ice sheet also impounded and deflected the Lower Amur and Uda Rivers which resulted in reorganization of their drainage systems. The Okhotsk marine ice sheet was grounded on seafloor and reached to the outer (southern) edge of the submarine Academy Sill. From that limit, the ice sheet extended farther south, across the deep Kurile Basin, as a floating ice shelf. The Okhotsk Sea and Beringian Ice Sheets were the only "back-arc" Quaternary glaciers; they were two major sources of icebergs, meltwater, and ice-rafted debris supplied to the North Pacific Ocean during the Ice Ages.