88 ka 以来冲绳海槽北部古环境演化：来自元素地球化学的证据

Paleoenvironment changes in the northern Okinawa Trough since 88ka:evidences from element geochemistry

对CSH1岩心全样沉积物样品进行元素地球化学分析,揭示了过去88ka冲绳海槽北部沉积物成分、水动力条件及陆源碎屑物质源区风化历史。冲绳海槽北部碎屑沉积物母岩主要以长英质为主,在MIS 1期沉积物存在大量火山源物质。过去88ka,沉积物源区风化程度较弱,但是自冰消期以来有逐渐增强的趋势。沉积物Zr/Nb比值表明在MIS 1期和MIS 5.1期水动力较为强烈,这与黑潮增强的时间一致,可能是指示黑潮强度的一个指标。冲绳海槽北部陆坡沉积物陆源碎屑贡献在低海平面时期显著增加,而在MIS 1和MIS 5.1期生源贡献显著增加。冲绳海槽北部沉积物成分变化明显受到黑潮和入海径流的调节,实际上受海平面和东亚季风的制约。

Based on the analysis of major and minor elements in bulk sediments of core CSH1,we reconstructed the changes of sediment components,hydrodynamic conditions and weathering history in the provenance of terrigenous materials over the last 88 ka in the northern Okinawa Trough .The results show that the lithology of parent rock of the terrigenous detritus is felsic,and the volcanic detritus contributes significantly to the sediment components during MIS 1.Over the last 88 ka,the weathering in the provenance of terrigenous detribus is weak （WIP〈60%） but gradually increases since the last deglacial period.The Zr/Nb ratio indicates the hydrodynamic condition was much stronger during MIS 1 and MIS 5.1 in the northern Okinawa trough,a potential indicator of the strength of the Kuroshio,which occurs synchronically with the intensified Kuroshio.The terrigenous contributions significant-ly increased during lower sea level,while the biogenic contributions showed high values during MIS 1 and MIS 5.1. The sediment components are regulated by the Kuroshio and the runoff in the northern Okinawa Trough ,which in fact are controlled by sea level and the East Asian Monsoon.