Holocene dynamics in the Bering Strait inflow to the Arctic and the Beaufort Gyre circulation based on sedimentary records from the Chukchi Sea

Abstract

ABSTRACT The Beaufort Gyre (BG) and the Bering Strait inflow (BSI) are important elements of the Arctic Ocean circulation system and major controls on the distribution of Arctic sea ice. We report records of the quartz/feldspar and chlorite/illite ratios in three sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the BG circulation and the BSI during the Holocene. The quartz/feldspar ratio, a proxy of the BG strength, gradually decreased during the Holocene, suggesting a long-term decline in the BG strength, consistent with orbitally-controlled decrease in summer insolation. We suppose that the BG rotation weakened as a result of increasing stability of sea-ice cover at the margins of the Canada Basin, driven by decreasing insolation. Millennial to multi-centennial variability in the quartz/feldspar ratio (the BG circulation) is consistent with fluctuations in solar irradiance, suggesting that solar activity affected the BG strength on these timescales. The BSI approximated by the chlorite/illite record shows intensified flow from the Bering Sea to the Arctic during the middle Holocene, which is attributed primarily to the effect of an overall weaker Aleutian Low. The middle Holocene intensification of the BSI was associated with decrease in sea-ice concentrations and increase in marine production, as indicated by biomarker concentrations, suggesting an influence of the BSI on sea-ice distribution and biological production in the Chukchi Sea.