琼东南盆地沉积岩心的地球化学特征

Geochemical Characteristics of Sediment Cores in Qiongdongnan Basin

根据琼东南盆地北部边缘碳酸盐岩发育层段所取得的3口井的岩心样品,对该区域的元素地球化学特征进行了分析研究,初步确定:Y ING6井岩石为白云岩,BD23-1-1井为石灰岩,QH36-2-1井主要为白云岩,还含有其他一些非碳酸盐自生矿物和陆源矿物混入物。碳酸盐岩中稀土元素分异程度较小,呈现出较明显的Ce负异常和Eu正异常特征,指示碳酸盐岩主要沉积于弱氧化和弱还原环境;样品中Sr、Ba含量较高,ρ(Sr)/ρ(Ba)比值可以用来区分海洋沉积物与大陆沉积物,ρ(Sr)/ρ(Ba)>1,代表海洋沉积,ρ(Sr)/ρ(Ba)<1,代表大陆沉积,研究区沉积物既有海洋生物碎屑也有陆源碎屑。

Trace and major elements were measured in sediment cores collected at the edge of Qiongdongnan（QDN） basin.Changes of element contents reflect the material sources and sedimentary environmental changes.Preliminary analysis result is that the lithologic character of YING6 well is dolomite,BD23-1-1 well is limestone and QH36-2-1 well is dolomite.Besides,there are a lot of anauthigenic minerals and detrital materials of terrigenous origin.Changes of element contents reflect that differentiation in rare earth elements of carbonatites is very small,and it shows sharp Ce negative anomaly and Eu normal anomaly,indicating that carbonates sediment in QDN were deposited in weak oxic environment and weak reducing environment.In sediments cores,the content of Sr and Ba is more,and its ratio can distinguish marine sediment from continental sediment,with Sr/Ba1,indicating marine sediment;Sr/Ba1,indicating continental sediment;and there are marine organisms clastic sediments and detrital materials of terrigenous origin in QDN basin.