内蒙古乌奴格吐山大型铜钼矿床成矿流体来源及演化:流体包裹体及氢氧同位素地球化学证据  

Source and evolution of ore-fluid in Wunugetushan large Cu-Mo deposit,Inner Mongolia: evidence from fluid inclusions and hydrogen and oxygen isotopic geochemistry

作　　者：谭钢 佘宏全[2] 印建平[1] 杨郧城 李进文[2] 向安平[2] 张斌[2] 

机构地区：[1]中国有色金属建设股份有限公司,北京100029 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《世界地质》2013年第3期463-482,共20页World Geology

基　　金：国家科技支撑计划项目(2006BAB01A10);国家地质调查项目(1212011120992)联合资助

摘　　要：内蒙古乌奴格吐山大型铜钼矿床位于得尔布干成矿带西南段。矿体产于燕山早期二长花岗斑岩、流纹斑岩等构成的火山通道相与外围黑云母花岗岩接触带内外。矿床从中心向外发育典型的热液蚀变分带:钾化带、绢英岩化带和伊利石—水白云母化带。根据矿物组合不同,将热液成矿期分为早、中、晚3个阶段,其矿物组合分别为石英+钾长石+黄铁矿±辉钼矿、石英+绢云母+黄铜矿±辉钼矿+黄铁矿、石英+碳酸盐矿物+黄铁矿±闪锌矿。流体包裹体研究表明,乌山斑岩铜钼矿床发育L型富液相包裹体、V型富气相包裹体、S型含子矿物多相包裹体以及PG型纯气相包裹体。激光拉曼探针分析表明,石英斑晶和早阶段石英内水溶液包裹体除H2O外,多数含CO2,少数还含有CH4,C4H6等,含子矿物多相包裹体中子矿物主要有赤铁矿和黄铜矿;中阶段石英内只有少量V型包裹体含CO2,多数只有H2O,S型包裹体中子矿物有黄铜矿和黄铁矿,不再含有赤铁矿;而晚阶段石英内包裹体只含H2O。成矿流体由H2O-CO2-NaCl体系逐渐演化为H2O-NaCl体系。成矿早、中、晚3个阶段均一温度分别集中在340℃～460℃,240℃～360℃和120℃～240℃;盐度变化范围分别为5.32～53.26 wt%NaCl.eqv,1.65～41.58 wt%NaCl.eqv和0.66～14.05 wt%NaCl.eqv。初始流体是直接从浅部结晶冷凝的岩浆熔体中出熔的高温、高盐度和高氧逸度的成矿流体。富气相包裹体、富液相包裹体和含矿物的多相包裹体普遍共生,流体的沸腾可能是早期金属硫化物大量沉淀的重要机制。结合氢、氧同位素研究,认为中-晚阶段天水的混入导致的流体混合及降温作用在成矿过程中也发挥了重要作用。Wunugetushan large metallogenic belt. The orebodies are porphyry, and their contact zones are Cu-Mo deposit of Inner Mongolia, is located in the southwestern of Derbugan mainly hosted in the volcanic vent constituted by monzogranite and rhyolite with biotitic granite. The Cu-Mo deposit exhibits typical mineralization andalteration characters. Three alteration zones can be circled around the ore-bearing porphyry outwardly, including a center core of potassic and silicic alteration zone, outside ring zone of phyllic and illite-damourite zone. According to mineral assemblages, the ore-forming processes were divided into early, middle and late stages. In quartz pheno- cryst and quartz veins, four types of fluid inclusions are distinguished, namely L-type and V-type aqueous fluid in- clusions, daughter mineral bearing multiphase inclusions, and pure gaseous phase inclusions. According to the a- nalysis of Laser Raman probe, most aqueous fluid inclusions in quartz phenocryst and early-stage quartz veins con- tain H20 and CO2, some of them also contain CH4and C4H6 ; the daughter minerals in muhiphase inclusions in- clude hematite and chalcopyrite. In the middle-stage quartz veins, most fluid inclusions only consist of H20, and only some V-type inclusions contain CO2. The daughter minerals in muhiphase inclusions only include chalcopyrite and pyrite. There are only H20 in aqueous fluid inclusions in late-stage quartz veins. The ore-forming fluid evolved from H20-CO2-NaC1 system to H20-NaC1 fluid system gradually. Homogeneous temperatures in the early, middle and late stage quartz veins are 340℃ -460℃, 240℃ - 360℃ and 120℃ - 240℃ respectively, and the salinities are 5.32 -53.26wt% NaC1. eqv, 1.65 - 41.58wt% NaC1. eqv and 0. 66 - 14.05 wt% NaC1. eqv respectively. The initial fluids, exhibiting high-temperature, hypersaline and high-oxygen fugacity, were directly resulted from the fluid exsolution of the shallow crystallizing magma melt at the final stage. Coexistence of daughter mineral bear- ing muhiphase inc

关 键 词：流体包裹体 成矿作用 氢氧同位素 乌奴格吐山 内蒙古 

分 类 号：P618.4[天文地球—矿床学] P597[天文地球—地质学]