苏北盆地高邮凹陷E2d12碎屑岩稀土元素、微量元素地球化学特征及其地质意义

碎屑岩中的稀土元素与微量元素地球化学特征对判别大地构造背景、识别源区母岩性质、物源方向和重建古地理环境具有十分重要的示踪与指示作用。通过对苏北盆地高邮凹陷E2d21地层中稀土元素、微量元素的地球化学特征系统研究得出,E2d21沉积时期大地构造背景主要为活动大陆边缘,物源区类型为克拉通内的高地,具有稳定的地台沉积特点;碎屑岩的源岩主要来自于活动大陆边缘上的长英质源区和中酸性岛弧源区;物源区主要集中在凹陷周边一些构造凸起,如通扬隆起、柘垛低凸起、菱塘桥低凸起等;除真2断裂带附近主要为近海湖盆咸水沉积环境外,断裂带西侧和盆地内部水体盐度较低,为淡水-半咸水沉积环境。

Geochemistry Features and Its Significance of Rare-earth Elements and Trace Elements of Clastic Rocks of E2d12 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.