东昆仑约格鲁岩体暗色微粒包体特征及成因

对东昆仑约格鲁花岗岩体中暗色微粒包体的形态、大小、成分和分布等主要特征进行了较详细地研究。发现包体形态多样,以强烈的塑性流变为特征;包体大小悬殊,多数直径为几十厘米,最大者长轴达4m;包体成分以闪长质为主,结构总体上比寄主岩石的粒度细,岩体中不同部位的包体成分和结构都有所变化;包体分布不均匀,经常呈族状、条带状密集分布,具定向性。镜下研究发现,在包体中经常见到针状磷灰石、石英捕虏晶和斜长石的自形内核环带及增生边等现象,显示了岩浆混合成因的特点。

Features and origin of mafic microgranular enclaves in the Yuegelu granite in the Eastern Kunlun

The form,size,composition and distribution of mafic microgranular enclaves in the Yuegelu granite in the Eastern Kunlun are studied in detail.The enclaves are characterized by a great variety of forms and strong plastic rheology;their sizes are highly varied,being usually tens of centimeters in diame-ter,and the largest one has a long-axis length of up to400cm;they are mainly dioritic in composition and fine-grained than the host rock in texture as a whole,with the composition and texture varying somewhat in different parts of the rock;they are of uneven distribution,usually occurring densely as clus-ters and bands,and are oriented.Under the microscope,acicular apatite,quartz xenoliths and the idiomor-phic inner core zone and overgrowths of plagioclase are often found,all of which show the features of magma mixing.