LAUSR

Abstract We investigated the petrographic composition of coarse-grained clasts (>250 μm) in 117 core-top sediment samples from the western Arctic Ocean (the Amerasian Basin, Chukchi Sea, Alaskan/Beaufort margin and East Siberian Sea). Combined with analyses of bulk sediment mineralogy and grain size, we use the results to elucidate the terrigenous clastic sediment distribution patterns and transport modes in four different regions: (1) In the Chukchi Sea, the Bering Strait Inflow (BSI) contributes most of the sediments, with an additional terrigenous clastic contribution from Northern Alaska and Eastern Siberia. The highest coarse clastic content and a northward-fining of the grain-size distributions are attributed to the winnowing by the BSI. (2) In the Alaskan margin, terrigenous clasts are enriched in sea ice/anchor ice-transported quartz-rich sediments from Northern Alaska, and in addition the Alaska Coastal Current (ACC) contributes sediments originating from the Yukon River. Coarse-grained sediments accumulate near offshore Alaska with the finer fractions being transported further into the Chukchi Sea Shelf. (3) In the East Siberian Sea, coarse clasts are sparse and even absent in most study sites. Combined with the results of previous studies, we conclude that the terrigenous components are derived from the Laptev Sea and the adjacent Siberian Platform. They are transported by the Siberian Coastal Current and sea ice. (4) In the Canada Basin, terrigenous clasts are characterized by carbonate and quartz-rich sediments derived from the Canadian Arctic Archipelago (CAA). Sediments incorporated in sea ice/anchor ice drift from the CAA to the Beaufort Sea, where they combine with sediments from the Mackenzie River and are then transported into the Canada Basin by the Beaufort Gyre. Sediments and grain size in northern and southern Canada Basin also involve the early Holocene iceberg-entrained IRD from CAA and winnowing/nepheloid transported mica from marginal areas, respectively.