Paleoceanography of the Bering Sea advanced by IODP Expedition 323:: significant roles playing for global circulation and climate change

Our understanding of the paleoceanography of the Bering Sea has been considerably advanced by IODP Expedition 323. The expedition aimed to create a high-resolution record of changes in paleoceanography since the Pliocene in a relatively high-latitude region of the North Pacific, subject to polar amplification. The expedition recovered 660 cores, mainly high-quality Advanced Piston Cores (APC), with a total length of 5741 m of continuous cores from seven sites distributed around the perimeter of the Aleutian Basin, including the Bowers Ridge, the Bering Slope edge, and the Umnak Plateau. These cores are crucial to our understanding of sea-ice distribution, productivity, laminated sediments, input of detrital materials, the formation of the North Pacific Intermediate Water mass, the Pacific water mass entry, the history of the Arctic gateway, and the enigma of the intensification of the Northern Hemisphere Glaciation and the mid-Pleistocene Transition. The maximum ages of the cores are ~5 Ma at the Bowers Ridge sites and 2.5 Ma at the Bering Slope sites. Meltwater from the Alaskan Ice Sheet has influenced the Bering Sea since 4.3 Ma, increasing in influence at 3.3 and 2.8–2.5 Ma. The significant development of sea-ice formation was identified at two sites on the Bowers Ridge at 2.7 and 2.2–2.0 Ma, based on analysis of sea-ice related diatoms and silicoflagellates. Such sea-ice formation affected the extent of the North Pacific Intermediate Water in the Bering Sea, which was strengthened during cold intervals such as when the Bering Strait closed due to falling sea level.