日本海西南陆坡对马暖流影响下的全新世沉积物物源演化

PROVENANCE CHANGE OF HOLOCENE SEDIMENTS UNDER INFLUENCE OF THE TSUSHIMA WARM CURRENT ON THE SOUTHWESTERN SLOPE OF 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,进行了典型元素比值和物源判别函数方面的系统研究,以探讨全新世以来研究区沉积物的物质来源变化。结果表明,韩国的洛东江和中国的长江为所研究沉积物的主要来源。它们对研究区的物质贡献变化可划分为5个阶段,并主要受对马暖流演化和海平面上升的影响。全新世早期(9.6～6.5kaBP),特别是在两次冰融水事件MWP-1C(9.4～8.7kaBP)和MWP-1D(7.8～7.4kaBP)发生时,洛东江和长江对研究区沉积物组成的影响较大。随后,6.5～3.0和2.0～0.7kaBP,它们对研究区的影响减小,对应着此时东海北部及日本海西南部相对较弱的对马暖流强度。而在3.0～2.0和0.7kaBP以来,较强的对马暖流则将较多的洛东江和长江来源物质携带至研究区并沉降下来。

Synthetic analyses on typical element ratio and source discrimination function were carried out for a sediment core with high sedimentary rate collected along the Tsushima Warm Current（TWC） main stream on the southwestern slope of Japan Sea,in order to trace the sediment provenance change of the study area in the Holocene.Data suggest that the Nakdong River of Korea and Changjiang of China are the main source of the studied sediments.Affected by the TWC strength evolution and sea level rise,their contributions changed with time.There are five stages.In the early Holocene（9.6-6.5 kaBP）,especially during the two Melt Water Pulse（MWP） stages including MWP-1C（9.4-8.7 kaBP） and MWP-1D（7.8-7.4 kaBP）,the contribution of these rivers was high.Their contribution became lower during 6.5-3.0 kaBP and 2.0-0.7 kaBP,corresponding to the temporally weakening of TWC in the northern East China Sea and southwestern Japan Sea.In 3.0-2.0 kaBP and 0.7-0 kaBP,TWC was strengthened and more fluvial materials from the Nakdong River and Changjiang River were deposited in the study area.