新疆东天山突出山铜铁矿床地球化学特征与地质意义

Characteristics of geochemistry of Tuchushan cooper-iron deposit in the eastern Tianshan of Xinjiang and its geological significance

突出山铜铁矿床是东天山雅满苏石炭纪弧前—岛弧带中代表性的铁多金属矿床,矿体呈透镜状、脉状、似层状赋存于上石炭统底坎尔组下亚组火山岩中.矽卡岩阶段包裹体均一温度为151℃～＞380℃,盐度为1.91％～23.18％ NaCleq,密度为0.76～ 1.09 g/cm3,热液硫化物阶段包裹体均一温度为101 ℃～280℃,盐度为0.35％ ～ 23.05％ NaCleq,密度为0.74～1.13 g/cm3,表明成矿流体属于中-高温、中-低盐度、中-低密度的NaCl-H2O体系.（绿泥石）绿帘石矽卡岩、磁铁矿（镜铁矿）矿石、含磁铁矿灰岩的稀土配分模式均为轻稀土相对富集的右倾型（LREE/HREE=2.85 ～ 9.21）,以出现负铕异常（δEu=0.22～ 1.09）和铈异常不发育为特征,与底坎尔组火山岩相似,表明成矿物质来源于底坎尔组火山岩.矿区矽卡岩可能是火山热液交代碳酸盐岩形成的,成矿条件为中-高温、较为宽广的氧化还原环境,矿床成因属火山热液交代型。

Tuchushan copper-iron deposit is a representative iron-polymetallic deposit in Yamansu Carboniferous fore-arc/arc belt of eastern Tianshan, the orebodies occurs as lenses, veins and stratums, which is hosted in volcanic rocks of the Upper Carboniferous Dikan＇er Lower Formation. Homogenization temperature of fluid inclusions in skarn period vary from 151 ℃ to 〉380 ℃ , salinity range from 1.91% to 23.18% NaCl equiv, density range from 0.76 g/cm3 to 1.09 g/cm3 , and homogenization temperature of fluid inclusions in hydrothermal period vary from 101 ℃ to 280 ℃, salinity range from 0.35% to 23.05 % NaCl equiv, density range from 0.74 g/cm3 to 1.13 g/cm3, which have the characteristic of high-middle temperature, middle-low salinity and density, also belong to NaCl-H20 system. （Chlorite）-epidote skarn and magnetite-（specularite） ore have similar chondrite-normalized REE distribution patterns and are riched in LREE, is characterized by negative Eu anomaly and no Ce anomaly, also similar to volcanic of the Dikan＇er Lower Formation, indicating that ore-forming material was derived from the volcanic. The authors hold that skarn might have resulted from volcanic hydrothermal interaction with cabonate and deposit was formed in high-middle temperature, comparatively wide oxidation-reduction environment. The genesis of mineral deposit is belong to volcanic hydrothermal metasomatic type.