Metallogenic setting and mineralization-alteration characteristics of major skarn Fe-polymetallic deposits in Qimantag area,western Qinghai Province
Metallogenic setting and mineralization-alteration characteristics of major skarn Fe-polymetallic deposits in Qimantag area,western Qinghai Province
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作者：
Z. Yi
铁多金属矽卡岩型矿床广泛分布于青海省西部祁曼塔格地区。近年来，该区已成为最具找矿潜力的主要成矿带。大地构造上，属于东库仑造山带。成矿作用与印支期(204~237 Ma)闪长岩、花岗闪长岩和二长花岗岩有关。控矿地层由中元古代狼牙山组大理岩、硅质岩、奥陶纪-志留纪滩间山群大理岩、硅质岩、安山岩-玄武岩火山岩和石炭纪结晶石灰岩、碎屑岩组成。矿床中发育钙、镁、锰三种类型的夕卡岩钙质夕卡岩常与铁、铜、钼、(铅、锌)矿化共生，镁质夕卡岩主要与铁矿化共生，锰质夕卡岩常与铅锌(银)矿化共生。矿石矿物组合多种多样，具有一定的分带性。矿床内接触带钾质交代现象十分强烈。除不同类型的夕卡岩外，钾质交代作用也是重要的找矿标志之一。
Fe-polymetallic skarn deposits are widely distributed in the Qimantag area of western Qinghai Province.Recently,this area has become a major metallogenic belt with most promising ore potential.Geotectonically,it belongs to Eastern Kulun orogenic belt.Mineralization is related to Indosinian (204～237 Ma) diorite,granodiorite and mozonitic granite.Ore-controlling strata are composed of marble and silicalite of middle Proterozoic Langyashan Formation,marble,clasolite,silicalite and andesite-basaltic volcanic rocks of Ordovician-Silurian Tanjianshan Group,and crystalline limestone and clasolite of Carboniferous period.In the ore deposits,three types of skarns are developed,i.e.calcic,magnesian and manganoan types,with the first type being dominant.Calcic skarn is commonly associated with Fe,Cu,Mo,(Pb,Zn) mineralization,magnesian skarn is mainly associated with Fe mineralization,and manganoan skarn is always associated with Pb,Zn (Ag) mineralization.Mineral assemblage of the ores is extremely varied and has certain zonation.Potassic metasomatic phenomena are very entensive in the endo-contact zones of the deposits.In addition to different types of skarns,potassic metasomatism also constitutes one of the important ore-searching indicators.