Geological characteristics of the Yindonggou silver deposit in Hubei Province and its implication for ore genesis

湖北银洞沟矿床是中国为数不多的较为典型的大型银矿床.文中系统总结了该矿床的地质特征,初步提出了矿床的成因类型.研究结果表明:银洞沟矿床产于秦岭造山带东南部武当群变质火山岩中,矿体受韧性剪切带控制,矿石类型主要为石英脉型和少量蚀变岩型,围岩蚀变矿物组合主要为石英、铁白云石、白云母、钠长石、绿泥石、黄铁矿等,成矿流体特征为低盐度、低密度、富合CO_2±CH_4±N_2的水溶液,矿床上部为低品位银金矿体,中部为高品位银金矿体和少量铅锌矿体,深部银品位降低,金品位增高,同时出现较厚大铅锌矿体.其地质特征与典型的造山型矿床一致,表明其为一造山型银矿床,矿床矿化分带符合造山型矿床成矿模式--地壳连续模型.因此应该充分重视寻找矿山深部金、铅、锌、铜、钼等接替资源.Yindonggou silver deposit in Hubei Province is a typical giant silver deposit in China.Geological characteristics of this deposit are reported and the ore genesis is proposed in this study.Results of the previous studies and field evidences show that the deposit occurs in metamorphic volcanic rocks of the Wudang Group in Qinling orogen.Orebodies are controlled by shear zones and ores are mainly quartz-vein type.The mineral assemblages of wall rock alterations are mainly quartz,ankerite,muscovite,albite,chlorite,pyrite with minor other minerals.Ore fluid has low salinity,low density and bears CO_2± CH_4±N_2.Lower grade Ag+Au ore bodies occur in the upper part and higher grade Ag+Au ore bodies occur in the middle part as well as some small Zn+Pb ore bodies.In the lower part of the deposit,the grade of Ag decreases while the grade of Au increases and many big Zn+Pb ore bodies occur.This mineralization zoning is consistent with the crustal continuum model for orogenic-type deposits.These features are similar to those of orogenic gold deposits,which indicate that it is an orogenic silver deposit.The potential Au,Zn,Pb,Cu and Mo resources should be paid much attention.科技部科研项目; 全国危机矿山接替资源找矿项目; 国家自然科学基金中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)01177-1851