Spatial variations in sedimentary fluxes and paleoenvironment in the Sea of Okhotsk over the last 30 kyr

Abstract

Gaining insight into sedimentary fluxes provides a robust foundation for understanding the transport, deposition, and burial of terrestrial materials and other related substances at continental margins. The complex land-sea interactions and ocean dynamics have shaped the distinct sedimentary features of the Sea of Okhotsk across its spatial extent. However, our understanding of the evolutionary processes and the driving mechanisms of sedimentary fluxes in the Sea of Okhotsk during the late Quaternary remains elusive. Here, high-resolution sedimentological and elemental geochemical analyses of core LV87-55-1, retrieved from the central Sea of Okhotsk were selected to investigate sedimentary fluxes and paleoenvironmental history of this sea since 30 ka BP. The results indicate that the fluxes of detrital sediments were elevated during the last glacial period (30–14.7 ka BP), dominated by fine-grained detrital sediments sourced from Siberian mainland. During the last deglaciation and early to middle Holocene (14.7–4.2 ka BP), sedimentary fluxes decreased, and detrital sediments consisted of a mixture of sediments from the Siberian mainland, the Amur River, and Sakhalin Island. During the late Holocene (<4.2 ka BP), the sedimentary fluxes reached their lowest level, while sediments were dominated by coarse-grained fractions from Sakhalin Island and the Okhotsk-Chukotka volcanic belt. Combined with a compilation of published data from 10 cores, we found distinct spatial variations in sedimentary fluxes across the Sea of Okhotsk. The sedimentary fluxes were high in the central and southern Sea of Okhotsk during the last glacial period and decreased since the last deglaciation, in contrast to the northern part, where the trend was reversed. Sea ice is the main environmental factor driving changes in sedimentary fluxes and detrital provenance, while sediment composition is also reworked by bottom current activity. We suggest that variations in sedimentary fluxes and sediment characteristics in the Sea of Okhotsk result from interactions between sea ice, bottom currents, river discharge, and sea level changes, which are in turn controlled by northern high-latitude insolation, atmospheric circulation and global ice volume changes.