滇西普洱银子山铜多金属矿矿床成因及找矿标志

Prospecting criteria and the genesis of Yinzishan copper-polymetallic deposit in Puer,Western Yunnan

银子山铜多金属矿床地处三江地区澜沧江成矿带南段,属复合成因矿床。矿体赋存于大凹子组(DCd)第二岩性段第三个韵律层内,矿床发育两种不同类型矿化,在形成时间及空间上有所区别:I号矿体产于英安岩的凝灰岩—火山角砾岩夹层内,呈似层状、透镜状,属火山喷流沉积—改造型铜多金属矿;II号矿体产于英安岩、凝灰岩—火山角砾岩层的蚀变带内呈透镜状,叠加于I号矿体之上,属火山热液型金矿体。结合矿床内岩石、主量元素及微量元素的分析,得出矿床内含矿岩石呈大离子亲石元素和高场强元素亏损的特征,总体属钙碱系列高钾—低钠型火山岩,火山旋回构成了成矿的根本因素。通过对矿床地质特征及成矿条件的总结,认为矿床为多期成矿改造叠加的复合型矿床,提出绢英岩化蚀变带及矿区西北段含矿层出露地段为有利的找矿部位。

Yinzishan copper polymetallic deposit is located in southern segment of Lancangjiang metallogenic belt,in Three-river area,which belongs to multiple-type ore deposit.The ore-bodies are hosted by the third rhythmic layering of the second lithologic member,Daaozi Formation.The Yinzishang copper deposit has hosts two types of mineralization.Of them,the No.I ore-body has hosted by tuff-volcanic breccia intercalation of dacite,which occurs in stratoid and lenticular forms belongs to volcanic effustion deposition-reworked type.Besides,the No.II ore-body has hosted by alteration zone of dacite/tuff-volcanic breccia,which superimposed on the No.I orebody belongs to volcanic hydrothermal type gold ore-body.Through the analysis of rock,major elements,trace elements in Yinzishan Copper Mine,this paper concluded that the ore-bearing rock has characterized by loss of lithophile element and high field strength elements.The volcanic rock belongs to the high K-low Na calc-alkaline series.Conclusively,the volcanic cycle constitute the fundamental factor of mineralizaiton.According to the summary of geological characteristics and metallogenic conditions,the authors have drawn the conclusion that the Yinzishan copper-polymetallic deposit is a compound origin deposit which goes through multiple phase and superimposed sedimentation.In addition,the authors put forward that the sericite-quartz alteration zone and the outcrop of ore-bearing strata in west-northern segment are the favorable prospecting area.