Geochemical records of sediment cores from the Sea of Japan

Intervals of organic C- and carbonate-rich laminated sediments occur in the Sea of Japan with roughly the same frequency as temperature changes observed in Greenland ice cores, providing clear evidence of rapid oceanographic change during the past 36 kyr. Planktonic foraminiferal d18O data suggest that only the laminated sediments deposited during the Last Glacial Maximum (LGM), and perhaps one other interval formed during a period of increased water column stratification. Sedimentary Re and Mo data are consistent with bottom waters that were sulfidic during the LGM and suboxic during other laminated intervals. Results of a numerical model of Corg and Re burial are consistent with a mechanism whereby an increased Corg flux to the seafloor drove oxygen concentrations toward depletion during times of deposition of the suboxic laminated intervals. Such a process could have resulted from increased upwelling driven either by increased deep water formation due to colder and/or more saline surface waters or by stronger northeasterly monsoonal winds.

日本海分布有富有机碳与碳酸盐的纹层状沉积序列，其形成频率与格陵兰冰芯记录的温度变化频率大致相当，为过去36千年间发生的快速海洋学变化提供了明确证据。浮游有孔虫d¹⁸O数据显示，仅末次冰盛期（Last Glacial Maximum，LGM）期间沉积的纹层状沉积物，以及另有一个形成于水体层化增强时期的沉积层序，符合该频率特征。沉积岩芯中的铼（Re）与钼（Mo）数据表明，末次冰盛期时期的底层水体为硫化环境，而其他纹层沉积时期的底层水体则处于亚氧化状态。有机碳（Corg）与铼埋藏数值模型的结果，与下述机制高度吻合：在亚氧化纹层沉积阶段，向海底输送的有机碳通量增加，促使底层水体溶氧浓度逐步趋近于耗竭。该过程可能由两类因素驱动：一是因表层水体变冷和/或盐度升高导致深水形成作用增强，进而引发上升流活动加剧；二是东北季风环流强度增大，直接推动上升流增强。