Evolution of Northwest Pacific Sedimentation Patterns since 6 Ma (Site 882)

Abstract

A high-resolution carbonate record from the northwest Pacific covering roughly the last 6 m.y. generally shows "Atlantic-type" interglacial spikes of carbonate preservation. These spikes parallel maxima in the biogenic opal and total organic carbon records, indicating increased productivity during interglacials. The variations can be explained best by changes in the advection of nutrient- rich deep water originating in the North Atlantic and ultimately upwelling in the northwestern Pacific, the terminus of the global salinity conveyor belt. During interglacial times, the conveyor was enhanced, which led to increased upwelling of nutrient-rich deep water and, therefore, to a regionally enhanced surface productivity. As a result, carbonate production and accumulation at Site 882 exceeded the local carbonate dissolution during early/peak interglacial times, in contrast to the central Pacific where CaCO3 corrosion is characteristic of warm stages as a response to an increase in the circulation of the salinity conveyor belt, leading to the "Pacific type" of interglacial minima of carbonate accumulation.