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Reconstruction of paleoceanographic changes in the Japan Sea in response to centennial to millennial-scale global climatic changes

重建日本海古海洋变化以应对百年至千年规模的全球气候变化

基本信息

批准号：
08458141
负责人：
TADA Ryuji
金额：
$ 3.46万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

This research is aimed to clarify paleoceanographic changes of the Japan Sea in association with centennial to milennial-scale global climatic changes known as Dansgaard-Oeschger [D-O] Cycles through the high resolution analysis of piston cores retrieved from the deeper partrs of the Japan Sea. Two piston cores KT 94-15-PC-5 and PC-9 which were retrieved from the sites off Akita were used for analyzes of bulk chemistry, bulk mineralogy, sedimentary structures such as lamination and bioturbation, and diatom assemblage. Based on the results of these analyzes, character of the surface water, bottom water oxygenationlevel, and contribution of aeolian flux from the continent were evaluated. By examining temporal and spatial changes of these parameters, weinvestigated a) how character of the surface water and oxygenation level of the deep water had been changed in response to D-OCycles, b) what the phase relationship between these two parameters and D-O Cycles was, and c) what the phase rela … More tionship of between aridity changes in inland East Asia deduced from the contribution of aeolian materials and D-O Cycle was.The results suggest 1) the dark layrs in the Japan Sea sediments correlate to interstadials of D-O Cycles, 2) the dark layrs always preserve parallel laminations which suggests deposition under suboxic to euxinic bottom water conditions, 3) sudden increases in contribution of aeolian materials generally coincide with but sometimes lead or lag by one sample (c. a. 600 yrs) from the start of deposition of the dark layrs, and 4) the linear sedimentation rates of the dark layrs tend to be slower than the adjacent light layrs and consequently aeolian flux also seems to have been smaller in the dark layrs than in the adjacent light layrs. The observed phase shift of one sample (c. a. 600 yrs) between the start of the dark layrs deposition and the increase in aeolian contribution could be attributed to the fact each sample represent a 2.5cm stratigraphic interval and sometimes cover the boundary between the dark land light layrs. The possible phase lag of aeolian contribution decrease behind the start of deposition of the dark layrs by as much as 3000 yrs previously pointed out by us based on the analyzes of 1500 yrs interval samples from ODP Site 797 seems to be suppositional and caused by coarse and not continuous sampling. Less

本研究的目的是澄清古海洋学变化的日本海与百年至千年尺度的全球气候变化称为Dansgaard-Oeschger [D-O]周期通过高分辨率分析活塞芯检索从日本海的更深的partrs。利用从日本秋田海域采集的KT 94-15-PC-5和PC-9两个活塞岩心，进行了体化学、体矿物学、沉积构造（如纹层和生物扰动）和硅藻组合的分析。在此基础上，分析了该海域表层水、底层水的含氧水平，以及来自大陆的风成通量对该海域的贡献。通过考察这些参数的时空变化，我们研究了表层水的性质和深层水的氧合水平是如何响应D-O循环而发生变化的，B）这两个参数与D-O循环之间的相位关系，以及c）这两个参数与D-O循环之间的相位关系 ...更多信息根据风成物质的贡献推断出东亚内陆干旱化变化与D-O旋回的关系，结果表明：1）日本海沉积物中的暗层与D-O旋回的阶间相对应，2）暗层始终保持平行纹层，表明沉积环境为亚氧至缺氧底层水条件，3）风成物质贡献的突然增加通常与一个样本相一致，但有时会领先或滞后一个样本（c. a. 600年），以及4）暗层的线性沉降速率往往比相邻的亮层慢，因此暗层的风成通量似乎也比相邻的亮层小。观察到的一个样品的相移（c. a. 600年）之间的开始黑暗层沉积和风成作用的增加，可以归因于这样一个事实，即每个样品代表一个2.5厘米的地层间隔，有时覆盖之间的边界黑暗的土地轻层。根据对ODP 797站1500年间隔样品的分析，我们曾指出，风成作用的相位滞后可能比暗层沉积开始的时间晚3000年，这似乎是一种假设，是由于取样粗糙和不连续造成的。少