铜陵冬瓜山铜矿成矿流体特征和演化  

Characteristics and Evolution of Ore Fluids in Dongguashan Copper Deposit, Anhui Province, China

作　　者：徐兆文[1] 黄顺生[2] 倪培[1] 陆现彩[1] 陆建军[1] 方长泉[1] 华明[1] 蒋少涌[1] 

机构地区：[1]南京大学地球科学系内生金属矿床成矿机制国家重点实验室,210093 [2]江苏省地质调查研究院,南京210018

出　　处：《地质论评》2005年第1期36-41,共6页Geological Review

基　　金：国家自然科学基金资助项目 (编号 49873 0 16;40 2 3 40 5 1);高等学校博士点专项科研基金 (编号 19990 2 843 5 )的成果

摘　　要：本文通过对安徽铜陵冬瓜山铜矿床内石英闪长斑岩中石英斑晶和夕卡岩矿物中流体包裹体显微测温及流体氢、氧同位素的研究认为 ,早期夕卡岩的形成可能涉及到高温岩浆流体过程 ,而在成矿过程中 ,以热液流体为主 ,至少发生了两次构造减压沸腾作用。第一次发生于静岩压力约为 112 MPa,流体温度主要介于 4 30～ 4 6 5℃之间 ,盐度介于 7.9%～ 5 3.7% (Na Cl eq.)之间 ,结果生成大量石英和磁铁矿 ;第二次发生于静岩压力约为 83.6 MPa,流体温度集中在 340～ 389℃之间 ,盐度介于 6 .6 %～ 5 2 .1% (Na Cl eq.)之间。在成矿近于结束时 ,有少量大气降水混入 ,形成了少量低温、低盐度流体。此外 ,保存在石英斑晶和早期夕卡岩矿物中的高温岩浆流体也曾发生沸腾作用。Based on the studies on microthermometry and H, O isotopes of fluid inclusion in the quartz phenocrysts at quartz diorite porphyry and fluid inclusions in skarn minerals, it is suggested the fluid responsible for early anhydrous skarn is dominantly magmatic water with high temperature. During the mineralization stages, hydrotherm played an important role and occurred two boiling events triggered by tectonic decompression processes. The first one occurred during quartz—magnetite—epidote stage with temperature of 430~465℃, salinity of 7 9%~53 7% (NaCl eq.) and lithostatic pressure of 112 MPa, resulting in the formation of magnetite and quartz. The second one occurred in the main mineralization period with temperature of 340 to 389℃, salinity of 6 6%~52 1% (NaCl eq.) and lithsatic pressure of 83 6 MPa. In the later stage, the ore fluid evolves to the low temperature, salinity aqueous solution because of the mixture of a little meteoric water from the country rocks. Furthermore, the fluid inclusions in the quartz phenocrysts and minerals of early skarn stage also show that fluid occurs boiling. The boilings caused by the tectonic decompression are much more favorable to the forming of the Dongguashan copper deposit.

关 键 词：成矿流体 特征和 冬瓜山铜矿床 演化 石英闪长斑岩 沸腾作用 岩浆流体 流体温度 流体包裹体 夕卡岩 显微测温 安徽铜陵 氧同位素 成矿过程 热液流体 大气降水 磁铁矿 低盐度 矿物 斑晶 高温 早期 压力 

分 类 号：P618.41[天文地球—矿床学]