西华山花岗岩及钨锡铍矿田成矿流体演化  

Xihuashan granite and evolution of ore-forming fluid of tungsten-tin-beryllium ore field

作　　者：刘家齐[1] 汪雄武[1] 曾贻善[2] 王晓地[1] 

机构地区：[1]宜昌地质矿产研究所,湖北宜昌443003 [2]北京大学地质学系,北京100871

出　　处：《华南地质与矿产》2002年第3期91-96,共6页Geology and Mineral Resources of South China

基　　金：国家自然科学基金 (4 9673 193 ;40 0 73 0 2 5 );国家地质调查项目 (2 0 0 13 90 0 0 18)

摘　　要：西华山花岗岩由早期侵入的斑状中粒黑云母花岗岩 (γ2 -15)和晚期侵入的中 -细粒黑云母花岗岩 (γ2 -25)及γ2 -25顶部与γ2 -15接触带上含少量钨铁矿的似伟晶岩边壳组成。钨锡铍主要成矿阶段的黑钨矿 -长石 -石英脉或黑钨矿 -绿柱石 -石英脉及无矿石英脉均穿切两期花岗岩及似伟晶岩壳。单个水晶体不同部位及不同时空分布的石英中流体包裹体Rb -Sr等时线年龄为 (130 .3± 6 .3)Ma和 (139.8± 4 .5 )Ma ,黑钨矿和萤石的Sm -Nd等时线年龄为 (139.2± 3)Ma和 (137.4±3)Ma。西华山和荡坪钨锡铍矿床成矿时代为 (135± 5 )Ma ,其成矿作用与晚期侵入的中粒 -中细粒黑云母花岗岩有关 ,矿脉中绿柱石熔体、熔 -流体包裹体的发现及其与流体包裹体的共存表明 ,西华山钨锡铍成矿作用自岩浆 -热液过渡阶段即已开始。成矿作用早期以岩浆及岩浆水为主 ,晚期成矿作用是在相对开放体系中进行的 ,并有大量大气降水混入。Xihuashan granite consists of the early stage porphyritic medium grained biotite granite(γ 2-1 5),the late stage medium grained biotite granite(γ 2-2 5), and marginal pegmatoid crust, which some wolframite is often found around the contact zone with γ 2-1 5 at the apex of γ 2-2 5. Wolframite (feldspar) quartz veins or wolframite beryl quartz veins, which are the major tungsten mineralization stage, intersect the granites and pegmatoid crust and are in turn cut by (wolframite)sulfide quartz veins and quartz veins formed in the late stage. Rb Sr isochron ages for fluid inclusions in different section of an individual quartz crystal in vugs and those for various metallogenic stages or different localities of quartz are respectively (130.3±6.3)Ma and (139.8± 4.5 )Ma, Sm Nd isochron age of wolframite and its coexisting fluorite is (139.2±3)Ma and ( 137.4 ±3)Ma. It is indicated that (135±5)Ma only one time of mineralization event,which is divided into multistage, has occurred in Xihuashan Dangping W Sn Be field. Xihuashan late stage medium grained biotite granite is related to W Sn Be mineralization.The presence of melt and melt solution inclusions in beryls from ore veins imply that mineralization has been begun during magmatic hydrothermal transitional phase.It is concluded that magma and magamtic water dominate in the early metallogenetic stage and a great deal of meteoric water is incorporated into ore forming fluid. The miarolitic quartz crystal grow in a relatively open system where effective oxygen isotopic exchange happened between crystal and meteoric water.

关 键 词：花岗岩 成矿流体 岩浆-热液过渡阶段 流体包裹体 钨锡铍矿床 西华山 成矿作用 

分 类 号：P618.67[天文地球—矿床学] P618.44[天文地球—地质学]