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High-resolution reconstruction of environmental change off the east coast of Japan since the last 50,000 years reconded in a marine sediment core.

在海洋沉积物岩芯中重新记录了过去 5 万年以来日本东海岸环境变化的高分辨率重建。

基本信息

批准号：
13304040
负责人：
OBA Tadamichi
金额：
$ 33.2万
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：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

The northwest Pacific, where the cold Oyashio and the warm Kuroshio Currents meet each other today, is the most sensitive region in the North Pacific for monitoring the migration of the western boundary corrects in response to the past climatic change. A long core (45.82 m length) was recovered from 2,224 m water depths off the central Japan during the IMAGES cruise in 2001. A multi-disciplinary study was carried out on the core by analyzing the following research items : color, grain size, mineral composition, paleomagnetism, δ^<18>O, δ^<13>C Opal, CaCO_3, species of diatoms, coccolithophorids, radiolaria, planktonic foraminifera and benthic foraminifera, CaCO_3 preservation, Uk37', TOC, C/N, δ^<13>C_<TOC>, δ^<15>N_<TOC>, biomakers and pollen. The following main results ware obtained. The δ^<18>O curve of G.bulloides is similar to the standard oxygen isotope curve, suggesting continuous deposition over the last 145 ka. All warm water indices yielded by the four microfossil assemblages (diatoms, coccolith, radiolaria, planktonic foraminifera) show temperature decreases during the MIS 2 and 6, and increases during the MIS 5, although their correlation coefficients with each other are not always high (between 0.5 and 0,6). The Alkenon-derived temperature (19℃) at the core top agrees with the mean annual SST at present time in this region. The SST at the end of the MIS 2 was 13℃, which is seen today about 4.5 degree latitude north than the core site. Similar migrations in SST are inferred from the coiling ratio of N.pachyderma. The C/N ratio, δ^<13>C_<TOC> and δ^<15>N_<TOC> indicate that the TOC is mainly of marine origin, although terrestrial origin slightly increases during the MIS 6. The curve of the warm pollen index is similar to the δ^<18>O curve of G.bulloides, except for the MIS 6 and 5e when the land temperature changes inferred from the pollen curve precede the δ^<18>O curve.

西北太平洋是北太平洋最敏感的区域，是监测西太平洋边界迁移的最敏感区域。西北太平洋是今天寒冷的Oyashio洋流和温暖的黑潮洋流相遇的地方。在2001年的图像巡航期间，从日本中部2224米深的水中打捞到了一个长达45.82米的岩芯。通过分析颜色、粒度、矿物组成、古地磁、δ^&lt；O、δ^&lt；13&gt；C Opal、CaCO_3、硅藻、球虫、放射虫、浮游有孔虫和底栖有孔虫、CaCO_3保存、Uk37‘、TOC、C/N、δ^&lt、13&gt、C_&lt、TOC&gt、δ^&lt、15&gt、N_&lt、TOC&gt；取得了以下主要结果。大泡石的δ^&lt；18&gt；O曲线与标准氧同位素曲线相似，表明145ka以来持续沉积。4个微化石组合(硅藻、球藻、放射虫、浮游有孔虫)所产生的暖水指数都显示出在MIS2和MIS6期间温度下降，在MIS5期间升高，尽管它们之间的相关系数并不总是很高(在0.5~0.6之间)。由Alkenon得到的核顶部温度(19℃)与该地区目前的年平均海温基本一致。在MIS2末尾的海温是13℃，今天可以看到它比核心站点北纬约4.5度。从厚皮新梢线虫的卷曲率可以推断出SST中类似的迁徙。C/N比δ^&lt；13&gt；C_&lt；TOC&gt；和δ^&lt；15&gt；N_&lt；TOC&gt；表明，TOC主要来自海相，但在MIS6期间陆源略有增加。暖花粉指数曲线与大花石棉的δ^&lt；18&gt；O曲线相似，只是MIS6和5E的地温变化先于δ^&lt；18&gt；O曲线。