陕西镇安县锡铜沟铅锌矿成矿地质特征

Metallogenic and Geological Characteristics of Xitonggou Lead and Zinc Deposit in Zhen’an County of Shaanxi Province

陕西镇安锡铜沟铅锌矿床过去一直被认为是SEDEX型矿床,笔者认为锡铜沟铅锌矿床可能属于造山型铅锌矿床。区内矿体斜切地层,赋矿地层为泥盆纪大枫沟组,通过氢、氧、硫及铅等同位素的研究,成矿的物质来源为南缘的泥盆纪海相沉积地层。成矿阶段划分为3个阶段,即早阶段为无矿石英阶段,中阶段为含硫化物-石英脉阶段,晚阶段为石英-碳酸盐脉阶段。矿床形成的时间应该是晚三叠世至侏罗纪,扬子板块与华北板块的陆陆碰撞,秦岭微板块内部发生了一系列的陆内俯冲或逆冲推覆,热异常驱动流体循环,萃取地层内的成矿元素,并将成矿元素搬运至有利于流体聚集、成矿物质卸载的空间,使成矿物质富集成矿。

Xitonggou lead and zinc deposit in Zhen'an county of Shaanxi province has commonly been considered as a sedimentary-exhalative (SEDEX) type deposit,but the author thinks that the deposit may be an orogenic type deposit.The ore bodies in the deposit area cut across the strata and these strata belong to the Devonian Dafengou formation.Through study on hydrogen,oxygen,sulfur and lead isotope of this deposit,it is found that the source of the ore-forming material is Devonian marine sedimentary strata in the southern margin.The mineralization may be divided into three stages.The early stage is quartz stage,the middle stage is sulfide-quartz stage,and the late stage is quartz-carbonate stage.The forming time should be formed in late Triassic to Jurassic period.When the Yangtze plate collided with the North China plate,the collision had led to a series of intracontinental subduction or thrust events inside Qinling microplate,and produced a thermal anomaly.Thermal anomaly drives fluid circulation,extracts ore-forming elements from strata,and transports them to space which is suitable for fluid accumulation and unloading of ore-forming materials.Thus,ore-forming materials have been concentrated.