东秦岭花岗岩的平均原子量及其与成岩成矿作用的关系

东秦岭不同构造单元中花岗岩类的平均原子量()有不同程度的差异。华北地台南缘为高值(20.65～21.15),秦岭褶皱系为中低值(20.35～20.43)。岩体的值与成岩物质来源和岩浆演化趋势有关,地台区花岗岩值介于“玄武岩地壳”平均值和“花岗岩地壳”平均值之间,而地槽区花岗岩则介于沉积壳层和花岗岩壳层之间。值东秦岭区域成矿作用分带与花岗岩的值分带有极明显的空间依存关系,成矿岩体的值远高于非成矿岩体,与金成矿作用有关岩体的值高于与铝多金属成矿作用有关的岩体。

THE MEAN ATOMIC WEIGHT STUDY OF GRANITES IN EASTERN QINLING MOUNTAINS

Eastern Qinling is an important region in China for its gold and molybdenum ore deposits,Situated in the joint part of two large tectonic elements, the district is characterised by its strong tectonic movement and frequent volcanic activities, especially the activities of intermediate and acidic magmatism. Among the widely spreaded granitic intrusions are mainly Yanshan granitoids and Caledonian granitoids in the second place. In the district, different kinds of endogenetic metal deposits are closely related to the granitic intrusions.Studies have been made previously to metal origin and magmatic evolution of the granitoids formed at different times and many useful results have been obtained. Through the study of mean atomic weights of granitoids in Eastern Qinling district, the author summerized some rules in this article.