桂北—湘南中生代玄武质岩石及其深源包体的地球化学性质和岩石成因探讨

桂北-湘南中生代玄武质岩石中含有丰富的深源包体，它们分别为橄榄岩、变形的辉长岩和中酸性片麻岩三大类，本文在论述上述岩石地球化学性质的基础上，探讨了它们之间的成因关系；寄主的中生代玄武质岩石为地幔楣榄岩部分熔融的产物，与辉长岩和中酸性片麻岩并无成因联系，后者属偶然包体，值得注意的是，深源包体中的变形辉长岩与片麻岩之间为分离结晶的成因关系，它们均为元古宙壳、幔间底侵玄武质岩浆的演化产物，其中辉长岩为底侵岩浆的堆积相，而片麻岩则为底侵岩浆经历分离结晶的堆积作用之后所剩下的残余岩浆的变质产物。

Geochemistry and Petrogenesis of Mesozoic Basaltic Rocks and Their Deep-SourceEnclaves in Northern Guangxi-Southern Hunan

In the Mesozoic basaltic rocks from northern Guangxisouthern Hunan, there are abundant deep-source enclaves, which can be divided into peridotite, gabbro and intermediate-acid gneiss. Based on petrology and geochemistry of these rocks, the present paper indicates that Mesozoic basaltic rocks are products of partial melting of peridotite instead of being related to gabbro and intermediate-acid gneiss which are merely accidental enclaves. It is noteworthy that gabbro and gneiss in these deep-source enclaves show genetic connection of fractional crystallization. They are evolutionary products of underplated basaltic magma, which was intruded between the crust and the mantle in Proterozoic. The gabbro is of the cumulus phase of underplated magma, whereas the gneiss is the product of residual magma after the fractional crystallization of underplated magma.