Sediment source strength, transport pathways and accumulation patterns on the Siberian–Arcticʹs Chukchi and Laptev shelves

In this study, we estimate sediment source strength and determine sediment transport/accumulation patterns on the Chukchi and Laptev shelves for lithogenic material from several key source regions. In the western Laptev Sea, sediments from the Siberian flood basalt province account for <20% of surface sediments, while detritus from the eastern Laptevʹs Lena and Yana Rivers constitutes as much as 40% of seafloor sediments. Eastern Laptev Sea sediments similarly reflect inputs from multiple sources; here, however, local inputs from the Lena and Yana Rivers are most prevalent. Chukchi Sea sediments are more homogeneous in composition, with sediments originating from the Okhotsk-Chukotsk volcanic belt and Bering Strait inflow comprising over 60% of surface sediments except near Wrangel Island and along sections of the Siberian coast. In the Chukchi portion of our study area, the dominant sediment dispersal pathways are from the Bering Strait region to the north and from Long Strait to the east, into the central Chukchi Sea. There appears to be comparatively minimal sediment transport parallel to the Siberian coast at our sample sites (>40 m water depth). In contrast, at our Laptev Sea sites (typically >20 m water depth) sediments supplied by the Lena and Yana Rivers move primarily eastward/northeastward parallel to the coast, with relatively minimal transport to the west/northwest or north to the central shelf. Good correspondence between sediment accumulation patterns and currents on the Chukchi shelf indicates water circulation is an important sediment transport mechanism in this marginal sea. In the Laptev Sea, a combination of river outflow, cyclonic water circulation and the Siberian Coastal Current controls sediment distribution. We speculate that sediment ice rafting may also affect shelf sedimentation patterns through a combination of factors. Our findings have implications for the fate of particle reactive contaminants released to the Siberian continental margin.