青海省兴海县铜峪沟铜矿床成矿物质和流体来源的地球化学探讨

Geochemistry Constraint on Ore-forming Material and Ore-forming Fluids of Tongyugou Copper Deposit in Xinghai County,Qinghai Province

青海铜峪沟铜矿床位于祁漫塔格—鄂拉山成矿亚带鄂拉山多金属矿带东南段。通过对铜峪沟铜矿床的矿石矿物微量元素地球化学研究及矿石矿物的稳定同位素研究,探讨该矿床的成矿物质及流体来源,确定矿床的成因。从测试结果来看,稀土元素配分模式为轻稀土较富集、重稀土亏损、分馏程度较高、Eu中度—强烈亏损,显示矿石物质来源为混合来源;硫同位素δ34S测试结果全为负值,属轻硫型,总体上揭示出硫主要来自地层的沉积硫;铅同位素测试数据表明矿石铅部分来自沉积成岩阶段,部分与印支期造山运动有关,表明成矿物质混合来源的特征,富成矿流体在成矿之前存在均一化过程。氢、氧、硅同位素研究表明成矿热液为原生岩浆水和变质热液水,反映成矿物质来源与岩浆热液活动有关。通过研究认为,铜峪沟铜矿床为矽卡岩型铜矿床。

Tongyugou copper deposit is located in the southeast segment of the Elashan polymetallic belt in Qimantage-Elashan ore-forming subzone.Based on the trace element geochemistry and the stable isotopes of Tonyugou copper deposit,this paper studied the source of ore-forming material and ore-forming fluids,identified the genesis of Tongyugou copper deposit.From the test results,the rare earth element distribution patterns are approximately consistent,the REE patterns are enriched in LREE and are depleted in HREE with high fraction-ation and negative Eu anomaly,demonstrating that the ore material comes from multi-source;sulfur isotope compositions δ34S measurement are full-negative,belong to light sulfur type,revealing that the whole S was from the sedimentary sulfur;the demographics of Pb isotopic compositions showing that the lead was mainly from the ore deposition diagenetic stage,and partly from the Indosinian orogeny,which is closely related to Indo-Chinese orogenic movement.Hydrogen,oxygen and silicon isotope studies shown that the metallogenic fluids stemmed from magmatic water and mixed with metamorphism hydrothermal.The overall reflection show that the ore-forming material sources was related to the magmatic-hydrothermal activities.In general,Tongyugou copper deposit is a skarn type copper deposit.