A High-Resolution Hydrographic Contrast Between the East China Sea and the Japan Sea Based on Foraminiferal Isotopic Records for the Late Holocene

Abstract

High-resolution foraminiferal isotopic records obtained from cores from the East China Sea and Japan Sea reveal a pattern of contrasting hydrographies for the last 6000 years. The first core, retrieved form the upper continental slope of the East China Sea, was analyzed for £_18O and£_13C in both Neogloboquadrina dutertrei (planktonic) and Uvigerina spp. (benthic) foraminifera and, hence, provides a record of paleoceanographic change through time. The relatively reduced amplitude of the planktonic£_18O signal relative to the benthic samples suggests some modification resulting form changes in the prevailing Kuroshio Current. A progressive depletion in both the£_18O and£_13C records of N. dutertrei over the last 2000 years suggests a warmer, more humid climate around the East China Sea. Isotopic records of the second core collected from the Japan Sea show a comparable temporal resolution ot those form the East China Sea, but they exhibit larger amplitudes presumably due to the more restricted hydrographic setting and greater sensitivity to environmental changes in that area. In addition to the temperature differences revealed by oxygen isotopes, the N. dutertrei£_13C records for these two cores also provide clues as to the cvolution of the Kuroshio Current during the late Holocene.

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