Sediment Provenance Changes in the Western Arctic Ocean in Response to Ice Rafting, Sea Level, and Oceanic Circulation Variations Since the Last Deglaciation

Two sediment piston cores were recovered from the Chukchi-Alaskan (05JPC) and Canadian Beaufort (02PC) margins to investigate grain-size, geochemical, and mineralogical compositions. This allowed the reconstruction of changes in detrital sediment provenance and transport related to climate variability since the last deglaciation. The end-member modeling analyses of grain size indicate that sea ice and nepheloid transport and the Mackenzie River sediment plume are major factors influencing sedimentation in the Chukchi-Alaskan and Canadian Beaufort margins, respectively. Unmixing of the sediment composition indicates that detrital sediments in core 02PC are derived mainly from the Mackenzie River, whereas sediments from core 05JPC are derived mainly from the Mackenzie River during the deglaciation and include a mixture of Holocene sediments from the Bering Strait, Mackenzie River, and Eurasian margin. The dolomite-rich ice-rafted debris recorded in both cores could be related to the different phases of iceberg discharges from the Amundsen Gulf Ice Stream. Quartz and feldspar-rich ice-rafted debris dated at 13 and 10.6kacal BP (before present) are related to the Lake Agassiz outburst in core 02PC and meltwater discharge from the Brooks Range glaciers in core 05JPC. Detrital proxies in core 02PC support the hypothesis that large meltwater and iceberg discharges from the Lake Agassiz outburst to the Arctic Ocean and Amundsen Gulf ice stream may have triggered the Younger Dryas. Finally, similar trends observed between sea level curves and our detrital proxy suggest that the sea level changes in the western Arctic Ocean have an important influence on the sediment dynamic during the early to middle Holocene.