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, interpreted as a proxy of the BG strength, gradually decreased during the Holocene, suggesting a long-term decline in the BG strength, consistent with an orbitally controlled decrease in summer insolation. We propose that the BG rotation weakened as a result of the 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 approximation by the chlorite / illite record, despite a considerable geographic variability, consistently shows intensified flow from the Bering Sea to the Arctic during the middle Holocene, which is attributed primarily to the effect of higher atmospheric pressure over the Aleutian Basin. The intensified BSI was associated with decrease in sea-ice concentrations and increase in marine production, as indicated by biomarker concentrations, suggesting a major influence of the BSI on sea-ice and biological conditions in the Chukchi Sea. Multi-century to millennial fluctuations, presumably controlled by solar activity, were also identified in a proxy-based BSI record characterized by the highest age resolution.

Holocene variability in sea ice cover, primary production, and Pacific‐Water inflow and climate change in the Chukchi and East Siberian Seas (Arctic Ocean)

“…Thus, an increase in these specific minerals determined in sediment cores from the Chukchi Sea can be used as signal for the re‐establishment of PW inflow during early Holocene times (cf. Ortiz et al , ; Nwaodua et al ., ; Kobayashi et al ., ; Yamamoto et al ., ).…”

“…Information on re‐opening of the Bering Strait and the resulting PW inflow into the Arctic Ocean can be obtained from mineralogical tracers (e.g. Stein, ; Ortiz et al ., ; Yamamoto et al ., ). As the Arctic Ocean is surrounded by very different geologic terrains (Fagel et al , , and references therein) which are characterized by very different rock lithologies and compositions, spatial trends in the lithology, mineralogy (i.e.…”

“…S3). Furthermore, the (chlorite+kaolinite)/illite ratios determined in the same core also support strong but highly variable PW inflow between ∼6.0 and 4k cal a BP but do not show the general decrease towards the late Holocene (Yamamoto et al ., ). The re‐establishment of PW inflow and its short‐term, high‐amplitude variability − as reflected in the chlorite+muscovite of both cores HLY0501‐6 and ARA2B‐1B (Fig.…”

“…In the Chukchi Sea, our study area, especially the clay minerals smectite and chlorite as well as muscovite (illites) are important tracers for sediment sources and transport processes (Fig. S4; Naidu et al , , ; Naidu and Mowatt, ; Stein, ; Ortiz et al , ; Nwaodua et al ., ; Kobayashi et al ., ; Yamamoto et al ., ). Here, large amounts of smectite and chlorite of up to about 30% were determined (Naidu et al , ; Naidu and Mowatt, ; Wahsner et al , ; Viscosi‐Shirley et al , ).…”

“…These data, in combination with other geochemical and mineralogical data, have been interpreted in terms of Holocene changes in sea ice cover, primary production and Pacific‐Water (PW) inflow. Most recently, Polyak et al () and Yamamoto et al () followed up this approach and published further important biomarker‐based Holocene sea ice records and mineralogical data indicative for PW inflow, obtained from the Chukchi Sea margin area (see Fig. for study sites 5 and 8).…”