南黄海3.50Ma以来海陆环境演变的元素地球化学记录

Elemental Geochemical Record of Land and Sea Environmental Evolution Since 3.50 Ma in South Yellow Sea

通过对南黄海西部陆架CSDP-1孔晚上新世—第四纪地层中的地球化学元素S、Sr和Ba的测试,结合该钻孔已发表的岩性、磁性地层和微体古生物等资料,综合分析发现:CSDP-1孔元素S、Sr、Ba质量分数及比值Sr/Ba在不同沉积相中的分布变化特征与研究区海陆沉积环境的变化密切相关,体现了S和Sr/Ba值的亲海相特性。S元素的高值主要出现在海相沉积环境中,对应了本区3.50Ma以来的海侵事件,可以指示本钻孔海陆环境。Sr/Ba值在U2沉积单元(1.66～0.83 Ma)的高值与海侵无关,认为主要是物质来源改变导致的沉积矿物组成发生变化所控制,而在U1沉积单元(0.83 Ma以来)Sr/Ba值能指示海陆环境的变化,表明0.83Ma以来海侵成为Sr/Ba值的主控因素。

Through testing the geochemical elements S,Sr and Ba in the strata from the Late Pliocene to Quaternary in the Core CSDP-1in the west shelf of South Yellow Sea,combined with the published lithological,magnetic stratigraphic and paleontological data,the authors found that the distribution and variation characteristics of these elements S,Sr,Ba and their ratio Sr/Ba in different sedimentary facies are closely related to the sedimentary environment changes in the study area,which reflects the pro-marine feature of S and Sr/Ba ratio.The high value of S element mainly occurs in marine sedimentary environment,corresponding to the transgressions since 3.50 Ma in this area,which indicates the sea and land environment of the core site.The high value of Sr/Ba ratio in U2 sedimentary unit(1.66-0.83Ma)is not related to transgression,but is mainly controlled by the change of material source,which leads to the changes of the sedimentary mineral composition;while in the U1 sedimentary units(since 0.83Ma),the Sr/Ba ratio indicates the change of the sea-land environment,showing that transgression has become the main control factor of the Sr/Ba ratio since 0.83 Ma.