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THE KUROSHIO MOVEMENT AND OCEANIC ENVIRONMENTAL CHANGE FOR THE LAST 150,000 YEARS

过去15万年的黑潮运动与海洋环境变化

基本信息

批准号：
07404028
负责人：
OBA Tadamichi
金额：
$ 22.72万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07404028/
关键词：
Kuroshio movement Oceanic environmental change Mineral assemblage Microfossil assemblage oxygen isotope Carbon isotope Nitrogen isotope Surrounding Japan 鉱物組織有孔虫 X線回折群集組成酵素同位体比

项目摘要

In order to reconstruct the paleoenvironmental changes related to the Kuroshio movement around the Japanese Islands since the last 150,000 years, we have carried out multidisciplinary analysis on about 15 marine sediment cores collected from the surrounding sea areas of Japan. The new results obtained are summarized as follows : 1) From the relative abundance of warm-water planktonic foraminifera in a core off Sanriku district, it has been inferred that the effect of the Kuroshio Current was strong during the oxygen isotopic stages 5._1 and 1, nearly absent during the stages 4 and 2, and sometime observed during the stage 3.2) From faunal and oxygen isotopic analysis of planktonic foraminifera in a core off Kashimanada, it has been revealed that the sea surface temperature(SST)decreased by several to nearly ten degrees Celsius at the last glacial maximum. 3) Compared to the Holocene SST,a decrease of 2-3ﾟC in SST during the last glacial period is revealed by the UK37-index analyzes in several cores off the southern coast of Japan. The accumulation rates of eolian dust (Quartz, Feldspar, Illite), as well as organic carbon content, increased during the last glacial period than in the Holocene. 4) Nannofossil assemblage in one of the southernmost core (30ﾟN) off the southern coast of Japan show fluctuations in accordance with the global climatic change since the last 130,000 years. The biological productivity in this core site, however, does not change so much. This suggests that the influence of the Kuroshio Current did not reach as far north as 30ﾟN during the last 130,000 years. 5) In a core from the Okinawa Trough, the organic carbon and nitrogen isotopic ratios has remained relatively constant since the last 40,000 years. This suggests that the Kuroshio Current has been convected into the Okinawa Trough for the last 40,000 years.

为了重建近15万年来与黑潮运动有关的日本列岛周围的古环境变化，我们对从日本周边海域收集的约15个海洋沉积物岩心进行了多学科分析。根据三陆近海一个岩心中暖水浮游有孔虫的相对丰度，推测在氧同位素5阶段，黑潮的影响很强。2）对鹿岛滩外一个岩芯中浮游有孔虫的区系和氧同位素分析表明，末次盛冰期时，海表温度（SST）下降了几至近10 ℃。3)与全新世SST相比，末次冰期期间SST下降了2-3 ℃，这是由日本南部沿海几个岩心的UK 37指数分析所揭示的。末次冰期风成尘（石英，长石，伊利石）的积累速率，以及有机碳含量，增加在末次冰期比全新世。4)日本南部海岸最南端的一个岩芯（30 ° N）的超微化石组合显示出与近13万年来全球气候变化相一致的波动。然而，这个核心站点的生物生产力并没有发生太大的变化。这表明，在过去的13万年里，黑潮的影响并没有达到北纬30度。5)在来自冲绳海槽的岩心中，有机碳和氮同位素比率自过去40，000年以来一直保持相对稳定。这表明在过去的40，000年里，黑潮一直对流进入冲绳海槽。