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晚第四纪以来伴随底层水含氧量的剧烈变化,浅色和深色沉积层的交替出现是日本海半远洋沉积物的主要特征.沉积特征分析表明,日本海Ulleung海盆南部KCES1孔的沉积物具有四种不同的沉积构造:均质、纹层、纹层状和混杂构造.深色沉积层一般具有纹层和纹层状构造,并且与我国内陆的千年尺度东亚夏季风强弱变化记录有很好的对应关系,表明纹层沉积物也具有千年尺度的变化规律,从而进一步说明了冰川性海平面变化和东亚夏季风波动应该是Ulleung海盆南部底层水溶解氧含量变化的主要原因.在暖期,在东亚夏季风降水相对增强的影响下,低温、低盐的东海沿岸水对日本海表层水体的贡献要大于对马暖流的贡献,日本海水体间的交换减弱,最终造成缺氧的海底沉积环境.在冷期,夏季风强度的减弱(冬季风增强)加快了日本海西北部深层水的生成,Ulleung海盆南部的底层水含氧量高,相应地沉积了具均质构造的浅色沉积物;在末次盛冰期最低海平面时,日本海成为一个封闭的海盆,降雨量高于蒸发量,水体出现分层,底层水处于停滞缺氧状态.自距今17.5 ka(日历年,下同)以来底层水含氧量较高,对马暖流逐渐成为影响日本海海洋沉积环境的主要因素.Ulleung海盆南部底层水的含氧量在YD期间有一定程度的降低,东海沿岸水的短暂强盛制约了深层水的流通.自距今10.5 ka以来对马暖流强盛,日本海海底处于富氧的沉积环境.“,”Sedimentological data are acquired from a piston core KCES1 off the southern Ulleung Basin margin in the East Sea (the Sea of Japan).These data include sediment color,X-ray radiographs,grain size distribution and AMS carbon-14 dating.Four kinds of sediments (homogeneous,laminated,crudely laminated and hybrid sediments) are identified according to the characteristics of the sedimentary structures that are considered to reflect changes in bottom-water oxygenation.The alternations of dark laminated /crudely laminated sediments and light homogeneous sediments represent millennial-scale variations which are possibly associated with the high-resolution changes in East Asian monsoon (EAM).The relative contributions of the East China Sea coastal water (ECSCW) and the Tsushima Warm Current (TWC) have been likely main reasons for the repetition of the anoxic and oxic depositional conditions in the East Sea since the last 48 ka BP.During the interstadial,the strengthened summer EAM was attributed to the development of expansion of the ECSCW because of more humid climate in central Asia,and more strongly low-salinity,nutrient-enriched water was introduced into the East Sea.The ventilation of deep water was restricted and the dark laminated layer deposited therefore under the anoxic bottom water condition.During the lowest stand of sea level in last glacial maximum,the isolated East Sea dominated by stratified water masses and the euxinic depositional environment formed.The homogenous sediments predominated since 17.5 ka BP indicate that the TWC has intruded into the East Sea gradually with the stepwise rise of sea level and the bottom water oxygen level is high.During the late Younger Dryas (YD) period,the last dark laminated layer deposited because the ventilation of bottom water was restricted by stronger summer EAM.The TWC has strengthened and the bottom water has become oxic again since 10.5 ka BP.