滇西北独龙江花岗岩中浆混包体特征

班公湖-东巧-怒江结合带(南段)西侧的独龙江花岗岩可划分为2个序列。早期序列(龙岗不若序列)富含混杂包体和混成包体。前者包括(石英)辉长苏长岩、辉长岩及辉长辉绿(玢)岩;后者由闪长岩、石英闪长玢岩、安山岩、安山玄武岩组成。从地球化学特征看,这些岩石由同源岩浆分异,并与生成寄主岩石的酸性岩浆混合而成。地球化学图解判别,浆混包体属钙碱性玄武岩系列,形成于岛弧环境,与寄主岩石———龙岗不若序列的生成环境一致。该类包体的存在,进一步证明了独龙江花岗岩早期序列(龙岗不若序列)由壳幔混源岩浆形成。

CHARACTERISTICS OF MAGMATIC MIX INCLUSION IN DULONGJIANG GRANITE OF NORTHWEST YUNNAN

The Dulongjiang Granite on the west side of Bangonghu-Dongqiao-Nu- jiang conjunction zone(south segment) can be divided into 2 succession. The early succession(Longgangburuo succession) is rich in mix-complex inclusion and mix-formation inclusion. The former include (quartz-) gabbro-norite, gabbro, gabbro-diabase(porphyrite). The latter is composed of diorite, quartz diorite porphyrite, andesite, andesite basalt. According to the geochemistry, these rocks are formed by the differentiation of cogenetic magma and the mixing of the differential rock with the acid magma of main rock. By the geochemical diagram discrimination, the magmatic mix inclusion belongs to the calc-alkali basalt series, formed in the island arc environment, which is consistent with that of the main rock(Longgangburuo succession). These kinds of inclusions confirm that the early succession(Longgangburuo succession) of Dulongjiang Granite is formed from the crust-mantle derived magma.