Geological characteristics and genesis of the Tuwu porphyry copper deposit, Hami, Xinjiang, Central Asia
Geological characteristics and genesis of the Tuwu porphyry copper deposit, Hami, Xinjiang, Central Asia
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DOI：
10.1016/j.oregeorev.2005.07.032
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发表时间：
2006-07
影响因子：
3.3
通讯作者：
Chunming Han;W. Xiao;Guochun Zhao;J. Mao;Jianmin Yang;Zhiliang Wang;Zhen Yan;Q. Mao
中科院分区：
文献类型：
--
作者：
Chunming Han;W. Xiao;Guochun Zhao;J. Mao;Jianmin Yang;Zhiliang Wang;Zhen Yan;Q. Mao
土武铜矿位于哈萨克斯坦-准噶尔板块和塔里木板块之间的大南湖-头素泉岛弧，是中国西部最大的斑岩铜矿床之一。含矿岩主要为早石炭世（333±2 Ma）花岗闪长岩和斜花岗斑岩。两个斑岩都是细长的。矿体为斑岩内细脉浸染型矿化体，铜品位为0.30% ~ 1.50%。成矿作用可划分为六个阶段。与矿化有关的围岩蚀变包括硅化、绿泥石化、绿帘石化、绢云母化和碳酸化。确定了3个蚀变带：绿泥岩-黑云母带、绿泥岩-黑云母带和丙岩带。Re-Os测年表明该矿床年龄为322.7±3ma。矿石硫化物的δ34S值在−0.9‰~ +1.3‰之间，平均值为0.11‰，反映了深部硫源。矿石中石英的δ18O值为7.70 ~ 9.70‰，绿泥石的δ18O值为6.62‰。石英和绿泥石的δ 18ow值在−5.37‰~ +6.62‰之间，δD值在−48‰~−63‰之间，表明成矿初期矿石流体主要为岩浆流体。而成矿后期的数值则减小，表明成矿过程中有大气水的加入。石英颗粒内流体包裹体尺寸一般为3 ~ 30 μm，气含量为5% ~ 60%，多为10% ~ 15%。流体包裹体的均一温度相对较低，介于101 ~ 409℃之间，大部分在100 ~ 200℃之间。矿化度范围为0.35 ~ 14.61 wt.% NaCl当量，平均值为7.72 wt.% NaCl当量，表明矿化度为中低盐度。含矿斜花岗斑岩表现出较强的重稀土元素亏缺，Yb和Y的平均值分别为0.65和5.90 ppm，是埃达克岩的地球化学特征。花岗岩内埃达克岩的地球化学特征为进一步找矿提供了特征指导。
The Tuwu copper deposit, located in the Dananhu–Tousuquan island arc between the Kazakhstan–Junggar and Tarim plates, is one of the largest porphyry copper deposits in western China. Ore-hosting rocks consist of Early Carboniferous (333±2 Ma) granodiorite- and plagiogranite-porphyries. Both the porphyries are elongate. The orebodies, consisting of veinlet-disseminated mineralization within the porphyries, grade range from 0.30% to 1.50% Cu. Mineralization can be assigned to six stages. Wall-rock alteration associated with the mineralization include silicification, chloritization, epidotization, sericitization and carbonatization. Three alteration zones have been recognized: phyllic zone, chlorite–biotite zone and propylitic zone. Re–Os dating indicates a 322.7±3 Ma age for the deposit. δ34S values of the ore sulfides range from −0.9‰ to +1.3‰, with a mean of 0.11‰, reflecting a deep sulfur source. δ18O values of quartz in the ores range from 7.70‰ to 9.70‰, and the δ18O value of chlorite in the ores is 6.62‰. Calculated δ18Owatervalues of quartz and chlorite range from −5.37‰ to +6.62‰ and the δD values range from −48‰ to −63‰, suggesting that the ore fluids were mainly magma-derived in the early stage of mineralization. However, values for the late mineralization stage decrease, suggesting the addition of meteoric waters during the mineralization. Fluid inclusions within quartz grains are generally 3 to 30 μm in size, with gas proportions ranging from 5% to 60%, mostly from 10% to 15%. Homogenization temperatures of fluid inclusions are relatively low, bracketed between 101 and 409 °C, mostly between 100 and 200 °C. Salinities exhibit a wide range from 0.35 to 14.61 wt.% NaCl equiv., with a mean of 7.72 wt.% NaCl equiv., suggesting that ore fluids have low to moderate salinity. The ore-bearing plagiogranite porphyries show a strong depletion in heavy rare-earth elements, with average values of Yb and Y of 0.65 and 5.90 ppm, respectively, this being a characteristic geochemical signature for adakite. The geochemical signature of the adakites within the granitoid rocks represents a characteristic guide for further exploration for copper porphyry-type ore deposit in Eastern Tianshan.