Palaeomagnetic investigation of three sediment cores from the Chukchi and Beaufort Sea margins was performed to better constrain the regional chronostratigraphy and to gain insights into sediment magnetic properties at the North American Arctic margin during the Holocene and the preceding deglaciation. Palaeomagnetic analyses reveal that the sediments under study are characterized by low‐coercivity ferrimagnetic minerals (magnetite), mostly in the pseudo‐single domain grain‐size range, and by a strong, stable, well‐defined remanent magnetization (MAD <5°). Age models for these sediment cores were constrained by comparing their palaeomagnetic secular variations (inclination, declination and relative palaeointensity) with previously published and independently dated sedimentary marine records from the study area. The magnetostratigraphical age models were verified by AMS radiocarbon dating tie points, tephrochronology and 210Pb‐based sedimentation rate estimate. The analysed cores 01JPC, 03PC and 02PC span c. 6000, 10 500 and 13 500 cal. a BP, respectively. The estimated sedimentation rates were stable and relatively high since the deglaciation in cores 01JPC (60 cm ka−1) and 03PC (40–70 cm ka−1). Core 02PC shows much lower Holocene sedimentation rates with a strong decrease after the deglaciation from ~60 to 10–20 cm ka−1. Overall, this study illustrates the usefulness of palaeomagnetism to improve the dating of late Quaternary sedimentary records in the Arctic Ocean.

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 10.6 ka cal 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.

The rare earth element concentrations and radiogenic isotope (Sr-Nd-Hf) compositions measured in bulk sediment leachates, together with bulk and clay mineralogical data, from two piston cores recovered in the Canadian Beaufort (AMD0214-02PC) and Chukchi-Alaskan (HLY0501-01JPC) margins were studied to investigate changes in the weathering regimes and deep water circulation during the Holocene. The coupled evolutions of the Nd and Hf isotopic compositions (expressed in epsilon units: ɛNd and ɛHf, respectively) are in good agreement with modern seawater and bulk sediment leachate data from Pacific water, Atlantic water, and the Mackenzie River. This agreement supports the idea that boundary exchange and brine formation likely play a significant role in the ɛNd and ɛHf values of the bottom waters in the western Arctic Ocean. The ɛNd and ɛHf records from the Canadian Beaufort and Chukchi-Alaskan margins reveal changes toward more radiogenic values from the early to late Holocene. Based on the ɛNd and ɛHf records, we suggest that the unradiogenic values are not controlled by water mass provenance and mixing but rather by provenance and a change in the weathering regime in the Mackenzie and Yukon drainage basins during the early to mid-Holocene. In contrast, the more radiogenic ɛNd and ɛHf values in the Chukchi-Alaskan margin and the mineralogical records in the late Holocene have primarily been controlled by an increase in the contributions of seawater and detrital particles from the Bering Sea via the Bering Strait inflow, which is likely related to major changes in the Pacific Ocean-atmospheric dynamics.

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