四川若尔盖地区西康群地球化学特征及其物源区和古风化程度分析

通过对四川省若尔盖地区西康群砂泥岩的主量元素、微量元素和稀土元素进行综合研究，发现本区砂泥岩的SiO₂ 、P₂O₅ 、MnO与PAAS有相同的含量,富集Na₂O、CaO，贫Al₂O₃ 、Fe₂O₃、MgO、K₂O和TiO₂。微量元素W含量大大高于上地壳丰度，Nb和Ta含量大大低于上地壳丰度，而与下地壳丰度相当，Sc的含量略低于上地壳丰度，造岩元素Sr 略高于地壳丰度值。稀土元素总量相对较高，平均值为133.97×10^-6，与地壳中的稀土元素总量112×10^-6较为接近。轻稀土元素相对于重稀土元素较为富集，具中等的负铕异常，稀土配分曲线均显示比较一致的右倾的轻稀土富集的配分模式。由此认为其地球化学特征与大陆岛弧和被动大陆边缘沉积物相似。综合其他地质资料认为若尔盖地区西康群砂泥岩的物源区可能为康滇古陆。

On the Geochemical Characteristics,Provenance and Paleoweathering Degree of Triassic Xikang Group in Ruoergai Area in Sichuan Province

Through a comprehensive study on the major elements,trace elements and rare earth elements of fluvial sand of Triassic Xikang Group in Ruoergai area in Sichuan Province,this paper found that the fluvial sand of this area has the same contents of SiO2,P2O5 and MnO as that in PAAS.It is enriched in Na2O,CaO and poored in Al2O3,Fe2O3,MgO,K2O and TiO2.The content of trace element W is far greater than the supracrustal abundance.The contents of Nb and Ta are far lower than the supracrustal abundance,but it is ab...