SPECIFICS OF LATE HOLOCENE SEDIMENTATION IN THE CHUKCHI SEA INFERRED FROM GRAIN SIZE AND MINERALOGICAL ANALYSES OF BOTTOM SEDIMENTS

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The aim of this work is to elucidate the specifics of recent sedimentation in the Chukchi Sea, based on the study of the material composition of Late Holocene bottom sediments. Analytical methods included grain size and mineralogical analyses. The results of 210Pb and 137Cs dating were used. The sediments are clayey silt and silty clay containing sand admixture and single gravel grains and pebble. The content of coarse-grained material increases slightly in the upper parts of the studied sections. This is probably due to the greater contribution of ice rafting to the recent Chukchi Sea sedimentation as a result of climate warming. The ultrafine- and fine-grained (0.25–0.05 mm) sandy material is dominated by light-fraction minerals. Volcanic glass was discovered in the sediments sampled in the southern and central areas of the Chukchi Sea. It might have been transported from the volcanoes of Alaska, the Aleutian Islands, and the Kamchatka Peninsula through the Bering Strait by the Pacific currents directed from south to north. The sediments collected in the southern, central, and northern areas of the Chukchi Sea differ in grain size and mineral composition. This is probably due to their remoteness from the coastline and provenance areas and is also caused by different rates of sedimentation.