日本海西南陆坡全新世对马暖流演化的沉积学和地球化学记录

EVOLUTION OF THE TSUSHIMA WARM CURRENT DURING THE HOLOCENE:SEDIMENTOLOGICAL AND GEOCHEMICAL RECORDS ON THE SOUTHWESTERN SLOPE OF EAST/JAPAN SEA

对日本海西南陆坡对马暖流主流轴下方高沉积速率沉积物柱状样,进行了沉积学和地球化学系统研究,以探讨全新世以来对马暖流在研究区的形成与演化,并得出了与附近地区古海洋学方法非常相近的结果,从而为今后研究区的对马暖流演化研究提供了沉积学和地球化学指标。据此,该柱状样中所记录的对马暖流演化可划分为5个主要阶段。全新世初期(9.6kaBP),对马暖流开始进入日本海,其强度较弱,同时,伴随着富营养东海沿岸水的影响,海底环境由还原性向氧化性转变;6.5kaBP时,对马暖流控制下的日本海南部现代对流模式最终建立起来,东海沿岸水的影响基本消失,随后,对马暖流明显减弱;3.0kaBP时,对马暖流再次增强并基本达到现在水平,且在随后的3ka里保持总体稳定,期间在2.0～0.7kaBP存在一次较弱的减弱过程。

Synthetic analyses on sedimentology and geochemistry of a sediment core with high deposition rate collected under the Tsushima Warm Current （TWC） axis on the southwestern slope of East/Japan Sea were carried out, in order to discuss the formation and evolution of TWC during the Holocene. Based on them, we got very similar results to those from paleoceanographical method in nearby areas. Thus, sedimentological and geochemical methods were offered for the future study on TWC evolution in the study area. Totally, there were five main evolution periods of TWC recorded in the study core. In the early Holocene, that is 9.6 kaBP, TWC began to weakly enter into the East/Japan Sea, together with the East China Sea Coast Water （ECSCW） enriched in nutrient matter, which led to the transfer of bottom environment from anoxic to oxic. At 6.5 kaBP, the modern current mode dominated by TWC in the southern East/Japan Sea finally formed, whereas the influence of ECSCW almost disappeared. After that, TWC obviously weakened. At 3.0 kaBP, TWC strengthened again to almost reach its present level, since then the circulation structure has been relatively stable, except for a weak depression of TWC during 2. 0-0. 7 kaBP.