东天山卡拉塔格地区玉带铜矿床地质特征及成因

Geological Characteristics and Genesis of Yudai Copper Deposit in Kalatag District,Eastern Tianshan

玉带铜矿床位于东天山大南湖—头苏泉岛弧带北缘的卡拉塔格地区,为近年来发现的中型铜矿床。通过野外地质调查和室内研究,对该矿床地质特征及成因进行探讨,发现矿床含矿地质建造为一套火山岩—火山碎屑岩,成矿地质体为石英闪长玢岩,矿体产于石英闪长玢岩体及其与围岩接触带,受断裂控制,主要呈脉状和透镜状。矿石类型以浸染状和细脉状为主,矿石组构以粒状结构,浸染状和细脉状构造为主,金属矿物主要为黄铜矿和黄铁矿,脉石矿物主要为石英,其次为绿泥石和绢云母。成矿过程可划分为石英—磁铁矿、钾长石—石英—黄铁矿、石英—黄铁矿—黄铜矿—辉钼矿和石英—碳酸盐—石膏4个阶段。矿区普遍发育钾化、硅化、绿泥石化、绿帘石化、绢云母化和碳酸盐化等蚀变,具带状分布特征,水平方向上由石英闪长玢岩中心向外可划分为钾化—硅化带、硅化—绢云母化带、泥化带和绿泥石—绿帘石化—碳酸盐化带;垂向上由石英闪长玢岩中心向外可划分为钾化—硅化带、硅化—绢云母化—黄铁矿化带和绿泥石—绿帘石化—碳酸盐化带。玉带铜矿床的成矿地质条件、矿体特征及围岩蚀变特征均与大南湖—头苏泉岛弧带斑岩型矿床一致,属于斑岩型铜矿床。

Yudai copper deposit is a newly discovered and medium-sized copper deposit located in the Kalatag district,northern Dananhu-Tousuquan island-arc belt,eastern Tianshan,NW China.Through field geological survey and laboratory research,the geological characteristics and genesis of the deposit were discussed.The ore-bearing geological formation is a set of volcanic-pyroclastic rocks,and the orebody is hosted in the porphyritic quartz diorite and volcanic rocks of the Daliugou Formation.It is controlled by the faults and is mainly vein and lenticular type.The ore types are mainly disseminated and veined and the structures are mainly granular,disseminated and veined.The metal minerals are mainly chalcopyrite and pyrite,and the gangue minerals are mainly quartz,followed by chlorite and sericite.The ore-forming process can be divided into four stages,namely quartz-magnetite stage,K-feldspar-quartz-pyrite stage,quartz-pyrite-chalcopyrite-molybdenite stage and quartzcarbonate-gypsum stage.The hydrothermal alteration is characterized by K-feldspar,silica,chlorite,epidote,sericite and carbonate.The alteration is typically zoned from center to outer with K-feldspar-silica zone,silicasericite zone,argillic zone and chlorite-epidote-carbonate zone,and K-feldspar-silica zone,silica-sericite-pyrite zone and chlorite-epidote-carbonate zone from top to bottom.The metallogenic geological conditions,ore body characteristics and hydrothermal alteration of the Yudai copper deposit are consistent with the porphyry copper deposit in the Dananhu-Tousuquan island-arc belt.Therefore,it is considered that Yudai copper deposit belongs to porphyry copper deposit.