江苏连云港—淮阴地区前寒武系沉积岩稀土地球化学及其时代

THE REE GEOCHEMISTRY OF SEDIMENTARY ROCKS IN THE LIANYUNGANG—HUAIYIN AREA,JIANGSU PROVINCE,AND THEIR GEOLOGIC AGE

江苏省连淮地区前寒武系沉积岩稀土组成除东海群下亚群外显示为后太古宙沉积岩的特征。不同时代沉积岩的稀土元素组成,以及地层微古植物组合、特征,地层接触关系和同位素年龄资料等表明,东海群属晚太古代—早元古代(Ar_2—Pt_1),海州群属中—晚元古代(Pt_(2-3)),石桥群属震旦纪(Z)。本区处于大陆边缘环境。

The REE distribution pattern of sedimentary rocks of the lower subgroup ofthe Donghai Group in the Lian-Huai area of Jiangsu Province shows that theybelong to Archean sedimentary rocks. They are characterized by lower REEcontents,depletion in light REE and normal Eu anomaly. Tgey are considered tobe of late Archean age. The REE distribution pattern of sedimentary rocks of the upper subgroupof the Donghai Group, Jingping Formation, Yuntai Formation and Shiqiao Groupshow that they belong to post-Archean sedimentary rocks. They are characterizedby higher REE contents, enrichment in light REE and negative Eu anomaly. Theupper subgroup of the Donghai Group is early proterozoic in age, the JingpingFormation middle Proterozoic in age, the Yuntai Formation middle-late Protero-zoic in age and the Shiqiao Group Sinian in age. The REE distribution of greywacke of the Haizhou Group exhibits thefeatures of continental-margin geosyncline: ∑REE 184. 35×10^(-6), LREE/HREE9.02, and δEu 0 .76.