浆液过渡态流体在矽卡岩型钨矿成矿过程中的作用——以湖南柿竹园钨锡多金属矿为例  

The role of magma-hydrothermal transition fluid in the skarn-type tungsten mineralization process:A case study from the Shizhuyuan tungsten and tin polymetallic ore deposit

作　　者：祝新友[1,2] 王京彬[1,2] 王艳丽[3] 陈细音 

机构地区：[1]北京矿产地质研究院,北京100012 [2]中色地科矿产勘查有限公司,北京100012 [3]有色金属矿产地质调查中心,北京100012

出　　处：《岩石学报》2015年第3期891-905,共15页Acta Petrologica Sinica

基　　金：国家科技支撑项目(2011BAB04B08);国土资源部公益性行业科研专项(201411024-1);全国危机矿山接替资源找矿项目(20089927)联合资助

摘　　要：湖南杮竹园是世界著名的大型矽卡岩型锡钨多金属矿床,产于千里山碱长花岗岩岩体南部接触带。矽卡岩中广泛发育网脉状碱交代脉和少量花岗岩脉、云英岩脉等各类脉体。碱交代脉主体由钾长石、萤石、少量石英、磁铁矿、黑钨矿、白钨矿及花岗岩构成,以往被统称为"云英岩脉"。其中早阶段碱交代脉中央发育花岗岩,边部为钾长石-萤石-黑钨矿,脉体两侧发育石榴子石透辉石矽卡岩化,对应矽卡岩阶段。晚阶段碱交代脉主要成分为钾长石、萤石,脉体及两侧出现大量阳起石、绿帘石、磁铁矿、白钨矿及辉钼矿、辉铋矿、自然铋等,对应退变质氧化物阶段。空间上,碱交代脉分布于矽卡岩和矽卡岩化大理岩中,不进入岩体。自花岗岩体→岩脉→碱交代脉→矽卡岩,Ca O、Ti O2、成矿元素W、Bi、Mo、Cu、Pb、Zn以及Sr、Ba等元素含量增高,显示出成矿元素向热液中富集,且岩浆和矽卡岩受到碳酸盐岩围岩的影响。碱交代脉的组构显示出其形成于富含成矿物质和挥发份流体的岩浆,其中广泛发育熔融包裹体和熔流包裹体,显示其浆液过渡态流体的成因性质。从岩浆晚期分异演化→热液阶段是连续演化的过程,块状云英岩和矽卡岩阶段,岩浆并未完全固结,成矿作用自岩浆固结之前已经开始。总结了杮竹园矿床成矿模型:碱长花岗岩岩浆演化晚期分异出的高度富含挥发份的熔浆,在岩体顶部聚集,部分形成似伟晶岩(壳)和块状云英岩以及条带状硅灰石符山石矽卡岩。进一步聚集以及矽卡岩化产生大量CO2引起大规模隐爆,富含挥发份的岩浆或浆液过渡态流体沿隐爆形成的碎裂裂隙进入碳酸盐岩围岩,与碳酸盐岩不断发生反应,在脉体边部形成钾长石化以及大范围的石榴子石透辉石矽卡岩化。至退变质氧化物阶段,随着岩浆冷凝和温度、压力的降低,地下水大范围参与,成矿流体Shizhuyuan large-scale skarn type tungsten and tin polymetallic ore deposit is located at Chenzhou County,Hunan Province,which occurred in the southern margin of the Qianlishan alkali feldspar granite body. The stockwork in skarn includes different types of veins,mostly alkali metamorphic vein（ AMV）,a few granite vein and greisen veins. The early stage AMV consists of granite vein in the central part,and K-feldspar-fluorite-wolframite in the margins,with garnet-diopside skarn alteration around the vein. The late stage AMV consists of K-feldspar, fluorite, minor actinolite, epidote, magnetite, scheelite, molybdenite, and bismuthinite. The AMV occurs only in the skarn and the skarnization marble,but is lack in the granite. The contents of Ca O,Ti O2,W,Bi,Mo,Cu,Pb,Zn,Sr and Ba show an increase trend from the granite,granite vein,AMV,to skarn,which may indicate an enrichment of ore materials from the magma to hydrothermal fluids. Evidence from the structure of granite vein in the center and the Kfeldspar-fluorite in the margins,together with occurrence of melt or melt-fluid inclusions in the AMV indicate that the veins may have formed from a unique fluid transition from magma to hydrothermal. The evolution of this fluid is continuous from magmatic to hydrothermal process,and the mineralization started before the magma fully consolidation. We suggest the following mineralization model： Firstly,the pegmatite,massive greisen and banded wollastone-garnet skarn formed in the top and outboard of the granite in the latest magmatic stage; then in the prograde stage after widespread hydrothermal-brecciation,magma or the magma-hydrothermal transition fluid flow along the fractures of the carbonate rocks,which formed the stockwork mineralization and cause alteration of Kfeldspar and garnet-diopside skarn. In the retrograde stage after magma consolidation,the mineral assemblage includes actinolite,magnetite,scheelite,molybdenum,and bismuth sulfides. In the latest sulfide stage,the temperature and fluid salinity decreased f

关 键 词：多金属矿 矽卡岩 矿床成因 浆液过渡态流体 成矿模型 钨矿 湖南 

分 类 号：P618.67[天文地球—矿床学]