四川盆地西南缘中侏罗统沙溪庙组沉积地球化学特征及其意义

Sedimentary Geochemisstry and Its Significances of the Middle Jurassic Shaximiao Formation on the Southwestern Margin of the Sichuan Basin

通过对四川盆地西南缘中侏罗统沙溪庙组碎屑岩的主量元素、微量元素、稀土元素进行综合研究,得出其主量元素富CaO、MnO,贫SiO2、Al2O3、Na2O、K2O;微量元素中富Cr、Zr、Cs、Th元素,贫Sr、Nb、Ta元素;稀土元素比地壳中的稀土元素总量相对较高,轻稀土元素弱富集,重稀土元素相对亏损,具有轻度的负铕异常。四川盆地西南缘沙溪庙组物源区为长英质岩区,物源区为大陆岛弧。沙溪庙期处于温暖、潮湿的沉积环境,具有中等程度的化学风化作用。为该区中侏罗世环境演化研究提供了基础资料。

Study of major elements and minor elements and REE indicates that clastic rock of the Middle Jurassic Shaximiao Formation on the southwestern margin of the Sichuan basin is characterized by enrichment in CaO,MnO,Cr,Zr,Ce and Th and depletion in SiO2,Al2O3,Na2O,K2O,Sr,Nb and Ta,HighΣREE with LREE enrichment and weakly negative Eu anomaly.From this it is concluded that the provenance of the Shaximiao Formation on the southwest margin of the Sichuan basin was felsic rock area in continental island arc in a warm,humid environment.