安徽铜陵胡村南铜钼矿床流体成矿过程

Fluid mineralization process of Hucunnan Cu-Mo deposit, Tongling,Anhui Province

胡村南铜钼矿床是在安徽铜陵铜（金）矿集区中发现的第一个矽卡岩-斑岩复合型铜钼矿床，在长江中下游成矿带具有特殊性和典型性。文章对该矿床进行了矿床地质和流体包裹体研究，旨在查明该矿床的流体成矿过程。胡村南铜钼矿床流体成矿过程可以划分为高温气成热液期、中高温热液期和低温热液期3个成矿期。高温气成热液期发育钾长石化和矽卡岩化，中高温热液期发育绿泥石化、绿帘石化和绢云母化，而低温热液期主要发育碳酸盐化。其中，中高温热液期为主要矿化期，形成辉钼矿和黄铜矿等多种硫化物网脉。高温气成热液期矿物中发育富液相和含子晶多相包裹体，中高温热液期矿物中也主要发育富液相包裹体和含子晶多相包裹体，但可见少量的富气相包裹体，低温热液期矿物中只发育富液相包裹体。从高温气成热液期经中高温热液期到低温热液期，成矿流体均一温度从43512以上，经203-458℃，降低到156-276℃；盐度w（NaCIcq）从14．0％～64．9％，经4．6％～47．5％，降低到1．0％～15．5％。成矿流体在其演化过程中发生过不混溶作用和沸腾作用。不混溶作用发生在气成热液期，使成矿流体中的成矿元素大量富集。沸腾作用发生在中高温热液期，导致成矿流体中的成矿元素卸载而沉淀出大量金属硫化物。

The Hucunnan deposit is the first skarn-porphyry multiple Cu-Mo deposit, which is found in the Tongling Cu （Au） ore-eoncentrated district of Anhui Province and appears special and typical in the Middle-Lower Yangtze metallogenic belt. Ore deposit geology and fluid inclusion studies have been carried out on this deposit in order to ascertain its fluid mineralization process. The fluid mineralization process is divided into three periods, i. e., high temperature pneumatolytie, middle to high temperature, and low temperature hydrothermal periods. Potash feldspathization and skarnization occurred in the first period, chloritization, epidotization and sericitiza-tion in the second period, and carbonization in the third period. Cu-Mo mineralization mainly took place in the second period, forming sulfide ore veins of molybdenite and chalcopyrite. Liquid-rich aqueous inclusions with daughter mineral-bearing multiphase inclusions are observed in minerals of the first and second periods, with mi- nor vapor-rich aqueous inclusions in minerals of the second periods. In contrast, only liquid-rich aqueous inclusions occur in minerals of the third period. Homogenization temperature and salinity of fluid inclusions decrease from over 435℃ and 14.0%--64.9% in the first period through 203--458℃ and 4.6% --47.5% the second period to 156--276℃ and 1.0%--15.5% the third period, respectively. The ore-forming fluids possibly expe- rienced fluid immisciblization and boiling during their evolution. The fluid immisciblization occurring in the first period lead to high enrichment of ore-forming elements in the ore-forming fluids, and fluid boiling existing in the second period, resulten in unloading of ore-forming elements in the ore-forming fluids responsible for the precipi- tation of many sulfides.