黑龙江省张广才岭南部早侏罗世花岗岩暗色微粒包体成因研究  

Genesis Study on Mafic Microgranular Enclave from Early Jurassic Granites in the Southern Zhangguangcai Mountains in Heilongjiang Province

作　　者：任永健 程烁 朱敬宾 王博 张明明 张旭 于汪 韩玥[2] 

机构地区：[1]中化矿山总局地质研究院,河北涿州072750 [2]国家行政学院,北京100089

出　　处：《现代地质》2017年第1期33-45,共13页Geoscience

基　　金：中国地质调查局项目"黑龙江省1:5万南蛤拉河子等四幅区域地质矿产调查"(1212011220474)

摘　　要：黑龙江省张广才岭南部早侏罗世花岗岩具有明显的岩浆混合特征。岩体中暗色微粒包体发育,主要为细粒闪长质岩浆包体,包体形态多样,与寄主岩呈截然、过渡关系。包体的矿物组合明显不平衡,如矿物具有定向排列的特点,斜长石发育自形环带并存在新、老两个世代,发育针状磷灰石。由电子探针对斜长石、角闪石和黑云母等矿物分析结果可知,寄主花岗岩和包体中各主要矿物含量基本一致。岩石地球化学特征研究显示,包体与寄主花岗岩关系密切,两者在稀土元素和微量元素方面也表现为明显的地球化学亲缘关系。这表明张广才岭南部早侏罗世花岗质岩石具有壳幔混合成因特征,暗色微粒包体是由较基性的地幔岩浆进入寄主岩浆中淬火结晶而成,花岗质岩浆的源区主要为新生的地壳物质。Early Jurassic granites in the Southern Zhangguangcai Mountains show magma-mixing characteristics.In the granite mafic microgranular enclaves are well developed. They are mostly fine-grained dioritic magmatic enclaves. The enclaves highly vary in shape and size and have clear-cut,vague or transitional relationships with host rocks. It is evident that the mineral assemblage of enclaves is not in balance. For example,mineral has the characteristic of directional arrangement; the plagioclase has developed from the epicyclic zone and has the presence of both the old and the new generations,and there also appears acicular apatite. Research on geochemistry shows that enclaves and their host granite are closely related both in the REE and trace elements,which also shows a significant geochemical affinity. It indicates that Early Jurassic granitic rocks are of crust-mantle mixing,and that dark enclaves are formed by relatively basic mantle magma into the host magma,quenching and crystallizing. Granitic magma sources are mainly from newborn crust substance in the Southern Zhangguangcai Mountains.

关 键 词：张广才岭 岩浆混合 早侏罗世花岗岩 暗色微粒包体 壳幔混合成因 黑龙江省 

分 类 号：P588[天文地球—岩石学]