日本海百年来沉积速率及粒度指示意义

对日本海中部、北部和西部四个深水多管沉积岩芯中的210Pb活度和沉积物粒度进行分析。结果显示百年以来大和海脊、日本海北部和西部陆坡沉积物以粉砂和黏土质粉砂为主。在日本海北部和大和海脊表层沉积物存在显著的生物扰动现象,而在西部陆坡不存在。基于恒定供给速率(CRS)模式建立了4个岩芯的年代框架,并计算了沉积速率。日本海现代平均沉积速率介于0.19~0.42 cm/a,最低值出现在大和海脊。4个岩芯中沉积物平均粒径呈现不同的分布模式,但是在1940年和1980年,沉积物粒度分布模式同时发生了改变,这可能与百年以来北太平洋十年涛动(PDO)及东亚夏季风震荡有关。

Sedimentation Rate and Implications of Sediment Grain Size of Japan Sea during the Last Hundred Years

Both of the 210Pb and sediment grain size in four deep-water multicore sediments which are located in the middle, north and west of Japan Sea are analyzed. The result shows that the sediments mainly consist of silt and clayey silt in the Yamato Ridge, northern part and western slope of Japan Sea over the last 100 years. There is a significant biological disturbance phenomenon of surface sediments in Yamato Ridge and the northern part of the Japan Sea, which does not exist in the western slope. According to the model of Constant Rate of Supply (CRS), we determined the age mode and calculated the sedimentation rate in four multicores. The modern average sedimentation rate in the Japan Sea varied between 0.19~0.42 cm/a, with a lowest value in Yamato Ridge. The mean sediment grain size of four cores showed different vertical patterns, but they simultaneously varied at about 1940 and 1980. We think such simultaneous change is closely related to the variations of Pacific Decadal Oscillation (PDO) and East Asian Summer Monsoon over the last 100 years.