湖南瑶岗仙花岗岩体中包体的地质地球化学特征与岩浆演化  

Geological and geochemical characteristics of xenoliths in Yaogangxian granite,Hunan Province

作　　者：祝新友[1] 王艳丽[2] 程细音[1] 田野[1] 

机构地区：[1]北京矿产地质研究院,北京100012 [2]有色金属矿产地质调查中心,北京100012

出　　处：《岩石矿物学杂志》2016年第1期16-32,共17页Acta Petrologica et Mineralogica

基　　金：国家科技支撑课题(2011BAB04B08);全国危机矿山接替资源找矿项目(20089927);国土资源部公益性行业科研专项(201411024-2);中国地质调查局项目(12120113086300)~~

摘　　要：湖南瑶岗仙钨矿床与成矿有关的碱长花岗岩岩株中发育多种类型包体,包括花岗岩、石英闪长斑岩、黑色包体及云英岩析离体等。这些包体的地质地球化学性质不同,来源和演化路径不同,记载着瑶岗仙花岗岩成因和岩浆分异演化的历史。对这些包体岩石学、地球化学的研究,结合岩体本身和区域燕山早期花岗岩基的对比研究,明确了花岗岩包体(Ⅰb)来自深部岩浆房中早期结晶的花岗岩,性质与区域花岗岩相近;石英闪长斑岩和黑色包体为前寒武纪变质岩在重熔时的残留;云英岩析离体是由花岗岩Ⅰ的岩浆晚期进一步分异形成的浆液过渡态流体结晶沉淀而成;产于石英斑岩中的细粒黑云母花岗岩包体(Ⅲb)捕获自岩浆房中分异的补体或补体上升时初步分异形成的花岗岩。形成瑶岗仙岩体的花岗岩高度富含挥发分,致使其中的包体强烈同化混染,并富含萤石、云母、电气石等以及硫化物矿物。瑶岗仙岩体是区域花岗岩基所代表的岩浆房高度分异的岩浆上侵的产物,石英斑岩岩浆直接来自于岩浆房结晶分异残留岩浆,而非瑶岗仙岩体的分异产物。建立了瑶岗仙地区燕山早期岩浆演化序列:岩浆房主体(二长花岗岩)→细粒黑云母花岗岩(补体)→碱长花岗岩岩株→浆液过渡态流体成矿→石英斑岩脉侵入。There are several types of xenoliths, such as monzonite, quartz diorite porphyry, black rock and greisen schlieren, in the alkali feldspar granite of the Yaogangxian tungsten deposit, Hunan Province. The xenoliths are different in geological and geochemical characteristics, sources and evolution paths, which implies the genesis and magma evolution history of the Yaogangxian granite. In this paper, the authors studied the petrology, geochemistry of the xenoliths, alkali feldspar granite, and monzonite batholiths formed in late Juras- sic period. It is detected that the monzonite inclusion （ I b） came from early crystallization of deep magma chamber similar to the monzonite batholith. The quartz diorite porphyry and black rock xenoliths seem to have been the residue of Precambrian metamorphic rocks in the melting. The greisen schlieren resulted from the transition from the alkali feldspar granite stage to the magma-hydrothermal stage. The fine biotite granite xenolith （Ⅲ b） in the quartz porphyry was captured from the supplementary granite which was differentiated from the main magma, or from the granite pluton formed from the supplementary rocks. The granite （I） was rich in volatiles,which resulted in strong contamination of the xenoliths, and a certain amount of fluorite, mica, tourmaline and sulfide minerals formed in the xenoliths. The Yaogangxian granite is a product of the intrusion of highly frac- tionated magma derived from the magma chamber equivalent to monzonite batholith. The quartz porphyry mag- ma directly resulted from the residue of segregation from fractional crystallization of magma chamber, rather than from the alkali feldspar granite of Yaogangxian. It is suggested that the magma evolved in order of magma chamber （main） （coarse monzonite） → fine biotite granite （supplementary） → alkali feldspar granite → magma-hydrothermal transition fluid （tungsten mineralization） → quartz porphyry veins.

关 键 词：湖南省 花岗岩 钨矿 捕虏体 岩浆演化 

分 类 号：P588.121[天文地球—岩石学] P59[天文地球—地质学]