Orbital-scale changes of sea ice conditions of Sea of Okhotsk during the last glaciation and the Holocene (MIS 4–MIS 1)

Abstract

In this paper, 5 schemes for reconstructing the sea ice conditions in the Sea of Okhotsk (the SO) during the last 74 kyr are presented. These schemes were constructed based on calculations of the ice rafted debris (IRD) fluxes in 16 sediment cores and the available published mineralogical data (Derkachev et al., 2004). We obtained new data on the orbital-scale changes of the IRD fluxes in the studied area for the last four marine isotopic stages (MIS). As a result, the key areas of sea ice formation and general direction of sea ice drift and, in turn, dominate direction of geostrophic wind in the SO were established for each of the investigated MISs. It allows us to suppose the positions of Siberian High and Aleutian Low during the individual MISs. At that, the sea ice was of predominantly seasonal for studied period, except for the northwestern and western parts of sea, where perennial sea ice fields were preserved over a period of several years during MIS 2. The variations of sea ice conditions attest to a particular type of atmospheric pressure field prevailing over the SO during individual MISs. The secondary sea ice drift directions points out that the predominant atmospheric pressure field during individual MISs were inconstant except the MIS 2.