朱溪钨铜多金属矿床石榴子石特征及其与成矿的关系

Characteristics of Garnet and Relationship of Mineralization from the Zhuxi W-Cu Polymetallic Deposits in the Jiangxi Province

朱溪矿床是近年在中国南方江南造山带新发现的超大型矽卡岩型钨铜多金属矿床。通过详细的野外调查与镜下观察,将朱溪矿区矽卡岩中的石榴子石划分为三个世代(I,II,III);电子探针分析数据表明,其石榴子石属钙铝-钙铁石榴子石系列,以钙铝榴石(Gr)为主,其次为钙铁榴石(Ad)。朱溪矿区常见白钨矿沿石榴子石的生长环带、边缘等部位交代的现象,白钨矿中部分的钙源自石榴子石,揭示石榴子石化过程有利于脆性裂隙的发育和热液流体的运移,能加速热液与围岩的化学反应过程,并为金属矿物的沉淀提供容矿场所。因此,朱溪矿区的石榴子石化过程构成了钨铜多金属矿成矿作用的一个重要阶段。

The Zhuxi W-Cu polymetallic deposit is a newly discovered super large-scale skarn deposit in the Jiangnan orogenic belt, South China. According to the detailed field investigations and studies under the microscope, garnet grains from the Zhuxi deposit were divided into three generations （I, II, III）. Microprobe analysis suggests that garnet is mainly classified to the calcium aluminum-calcium iron garnet series, with calcium aluminum garnet （Gr） as main type, followed by calcium iron garnet （Ad）. It is commonly observed that the scheelite grains metasomated garnet along the growth rings and margins or edges of garnet grains in the Zhuxi deposit. This process of garnetization is favorable for the development of brittle fracture and the migration of hydrothermal fluid, promoting the full reaction between hydrothermal and surrounding rocks, and providing the ore hosting sites for the precipitation of metal minerals. Garnetization in the Zhuxi deposit can be regarded as the stage of mineralization, part of the calcium in scheelite is derived from garnet.