Changing histories of glaciomarine deposition and water masses in the subarctic Okhotsk Sea of Late Quaternary

The subarctic Okhotsk Sea is one of the most important carbon sinks in the world and the main source areas of ​​North Pacific Intermediate Water (NPIW). The study of Late Quaternary paleoenvironmental changes of the ​​Okhotsk Sea and their effect factors are of great significance for understanding the responses of subpolar oceans to global climate change. Coarse fraction, drop stone, foraminiferal abundance, CaCO₃ content, benthic foraminifera Uvigerina spp. oxygen and carbon isotopes in the core ARC2-T00 collected from the Academy of Sciences on Rise of Southern Okhotsk Sea are tested, counted or analyzed by the authors and then the stratigraphic chronology of the core is established based on the comparison of the benthic foraminifera Uvigerina spp.-δ¹⁸O, the global deep-sea oxygen isotope stacks LR04-δ¹⁸O and the adjacent site OS03-1 Uvigerina spp.-δ¹⁸O. The results indicate that, in the most intervals of MIS 6—2, the sedimentary dynamic mechanisms in the Southern ​​Okhotsk Sea are dominated by westerlies, ocean currents and sea ice. Changes in the accumulation rate of eolian dust indicate that the westerlies strengthened and weakened during the glacials and the interglacials, respectively. The variation in the accumulation rate of sea ice sediments illustrates that during the glacials, sea ice deposition was severely influenced by the location of the seasonal sea ice depositional center at that time. Meanwhile, as indicated by proxies of sea ice and water masses, the southern ​​Okhotsk Sea was covered by seasonal sea ice and the upper Okhotsk Sea Intermediate Water (uOSIW) production was strengthened. Salinity variation in lower Okhotsk Sea Intermediate Water (lOSIW) may be related to inflow of the Forerunner of Soya Warm Current Water (FSCW), brine rejection due to sea ice formation and intrusion of the Pacific Deep Water (PDW).