北祁连加里东造山带塔儿沟夕卡岩-石英脉型钨矿床地质及成因  

Geology and Genesis of Ta′ergou Skarn-Quartz Vein Type Tungsten Deposit in North Qilian Caledonian Orogen, Northwest China

作　　者：张作衡[1] 毛景文[1] 杨建民[1] 王志良[1] 张招崇[2] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质科学院地质研究所,北京100037

出　　处：《矿床地质》2002年第2期200-211,共12页Mineral Deposits

基　　金：国家计委科技找矿项目 (JG947190 2 );原地质矿产部定向科研项目 (DKJ95 -16 );国家重大基础研究项目 (G19990 432 16 )的资助

摘　　要：文章总结了塔儿沟夕卡岩_黑钨矿石英脉型钨矿床的地质特征 ,对该矿床黑钨矿石英脉中的石英流体包裹体进行了均一温度、盐度和成分测试 ,并对矿石的氧同位素和硫同位素组成进行了测试 ,结合野牛滩岩体的岩石学、矿物学特征以及硫同位素组成特征 ,认为矿床的成矿流体为岩浆流体与大气降水的混合 ,钨很可能部分来自前寒武纪地层 ,部分来自野牛滩岩体分异演化所形成的含矿流体 ,同时岩体作为“巨大热能机” ,导致热水溶液对流循环 ,从围岩中萃取矿化元素 ,进而卸载成矿。The Ta′ergou tungsten deposit in Gansu Province of Northwest China is located in the western part of the North Qilian Caledonian orogen. It comprises skarn and wolframite quartz vein types of ores. The tungsten_bearing skarn was produced by the replacement of carbonate layers intercalated in the Precambrian schist and amphibolite, whereas wolframite_quartz ore veins were formed along a group of fractures that cut through horizontal skarns. The Ta′ergou tungsten deposit is genetically related to the Yeniutan Caledonian granodiorite intrusion and developed in the exocontact zone 300～500 m away from the intrusion at the surface and in exo_ and endocontanct zone along the sections. However, the granitoid displays poor differentiation and has low content of SiO 2 and high content of basic components. There are three types of fluid inclusions in the wolframite quartz vein system, i.e., aqueous, CO 2_H 2O and CO 2_rich. The homogenization temperatures of two_phase aqueous inclusions range from 140 to 380℃, their t m from -13.5℃ to -2.5℃, and their salinities w (NaCl eq ) based on t m from 4.2% to 17.4%; as for CO 2_H 2O inclusions, the values are 205℃ to 312℃ and 3% to 4.3%, respectively. The Laser Raman Spectroscopy analyses show that the inclusions contain a relatively high content of CO 2. The δ 34 S values of skarn type ores range from +8.1‰ to +12.7‰ and those of quartz vein ores from +9.3‰ to +14.9‰. This suggests that the δ 34 S values of both ores and intrusion (from +6.0‰ to +11.7‰) share the same source. The δ 18 O values of quartz are between +10.5‰ and +13.3‰ and those of wolframite between +3.4‰ and +5.1‰. The ore_forming fluid with δ 18 O water of 0.6‰ to 6.4‰ shows the mixing of magmatic fluid and meteoric water. Due to a high abundance of tungsten in the Precambrian metamorphic rocks and a low abundance in granitoid, the authors hold that tungsten of the deposit must have been mainly derived from the Precamb

关 键 词：矿床地质特征 成因 成矿模式 稳定同位素 夕卡岩-黑钨矿石英脉型钨矿床 流体包裹体 

分 类 号：P618.67[天文地球—矿床学]