Geochemistry Features and Its Significance of Rare-earth Elements and Trace Elements of Clastic Rocks of E_2d_1~2 in Gaoyou Depression of Subei Basin

The geochemistry features of rare-earth elements and trace elements in clastic rocks played an important role in tracing and instruction for discriminating geostructure settings,identifying mother rock characters,source directions and palaeo-geographic reconstructing environments.By systematically studying the characteristics of rare earth elements and trace elements in E2d12 of Gaoyou Sag,Subei Basin,the result indicates that the geostructural settings of E2d12 is a active continental margin and the type of provenance is highland in craton,it has the characteristics of stable platform sediment;the source rocks of clastic rocks are mainly from felsic provenance and intermediate acidity arc provenance in active continental margin area.The provenance is mainly centralized in some structural salients around the sag,such as Tongyang Uplift,Zheduo low bulge,Lingtangqiao low bulge and etc;except the areas around the Faulted Zone Zhen2as the brine sediment environment of offshore lake basin,the salinity of water in western fault zone and the inner basin is low,it is freshwater-brackish water depositional environment.