IODP Expedition 323: Pliocene-Pleistocene paleoceanography and climate history of the Bering Sea

Background and objectives The primary objective of drilling at Site U1345 was to study high-resolution HoloceneLate Pleistocene paleoceanography at a proximal gateway location to the Arctic Ocean at a water depth of ~1008 m. The drill site is located on an interfluve ridge near the large and broad head of Navarin Submarine Channel off the Bering Sea Shelf. It is anticipated to receive ample supply of terrigenous sediments from the shelf during the glacials. This is also in the area of high biological productivity called “Green Belt”. The Green Belt is formed by the Bering Slope Current (BSC), which has an origin in the incoming Alaskan Stream water in the western Aleutians into the Bering Sea. As going further northwest, the higher primary productivity and % organic carbon is observed at the sea-floor. Thus, the expectation of the impingement by the dissolved oxygen minimum zone (OMZ) in the past is relatively high at this site. Because the expected sedimentation rates are high with intermittently laminated sediment of mm to sub-mm in thickness (see below) it should be possible at this site to pursue reconstructing detailed climate changes of submillennial time scales. Therefore, it is possible to compare the data from this site with those from other pertinent high-resolution records from such places as the Santa Barbara Basin, the Cariaco Basin, and GISP2. It is also important to compare the vertical extent of water mass conditions in a basin wide scale extent including the Bowers Ridge and gateway as well as Umnak sites.