| 阿尔泰南缘乌拉斯沟铜矿床S-Pb-Sr-Nd-C-H-O同位素特征及其对成矿物质和流体来源限定 |
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| 引用本文： | 卢琦园,郑义,王成明,王岳军.阿尔泰南缘乌拉斯沟铜矿床S-Pb-Sr-Nd-C-H-O同位素特征及其对成矿物质和流体来源限定[J].地球科学,2018,43(9):3141-3153. |
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| 作者姓名： | 卢琦园 郑义 王成明 王岳军 |
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| 作者单位： | 1.中山大学地球科学与工程学院, 广东广州 510275 |
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| 基金项目： | 珠江科技新星项目201710010027广东省引进人才创新创业团队项目2016ZT06N331国家自然科学基金项目41502068广东省自然科学基金杰出青年基金项目2018B030306021科技部国家重点研发计划项目2016YFC0600408 |
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| 摘 要： | 新疆乌拉斯沟铜矿床位于阿尔泰造山带南缘克兰盆地内，为近年来新发现的矿床，受NW向断裂控制的脉状矿体产于泥盆系康布铁堡组变质火山岩系中，目前其成矿流体和成矿物质来源尚不明确.在细致的矿床地质研究基础上，通过开展S-Pb-Sr-Nd-C-H-O同位素分析，根据野外和显微镜下观察，可将乌拉斯沟铜矿床的形成划分为黄铁矿-磁铁矿-石英、黄铜矿-绿泥石-绿帘石-石英及石英-碳酸盐阶段.同位素分析结果显示:乌拉斯沟铜矿硫化物样品δ34S值为0.1‰~3.2‰，平均为1.6‰，落入未矿化围岩δ34S值范围（-4.7‰~18.68‰），矿石硫可能源自康布铁堡组.成矿晚阶段的方解石样品δ13CV-PDB‰=-1.1‰，δ18OV-PDB‰=-20.3‰，海相碳酸盐地层和有机碳是可能的碳质来源.8件黄铁矿的Pb同位素为206Pb/204Pb=17.939~18.508（平均18.255），207Pb/204Pb=15.519~15.674（平均15.578），208Pb/204Pb=37.881~38.653（平均38.209），与康布铁堡组围岩类似.初始ISr（220 Ma）为0.710 4~0.711 7，平均值为0.711 1，初始143Nd/144Nd值为0.512 002~0.512 240（平均0.512 103）.矿石Sr-Nd-Pb同位素组成均指示乌拉斯沟铜矿成矿物质可能主要源自围岩康布铁堡组，并可能有外来成矿物质的加入.流体的δDV-SMOW变化于-103.8‰~-92‰（平均值为-99.2‰），石英和方解石矿物的δ18OV-SMOW值集中在9.4‰~11.5‰（平均值为10.4‰），δ18OH2O值为2.1‰~4.2‰（平均值为3.1‰），结合流体包裹体物理化学特征，成矿热液可能来源于变质水，但可能受到大气降水的影响而偏移.因此，乌拉斯沟铜矿成矿物质主要来源于赋矿围岩的变质脱挥发分作用，这与造山型矿床的成矿机制吻合.
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| 关 键 词： | 乌拉斯沟铜矿 造山型矿床 阿尔泰造山带 同位素 地球化学 |
| 收稿时间： | 2018-01-25 |
S-Pb-Sr-Nd-C-H-O Isotopic Geochemistry of the Wulasigou Cu Deposit in the South Altay: Constraints for the Fluid and Metal Sources |
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| Abstract: | The Wulasigou Cu deposit is a recent discovered ore deposit, located in Devonian volcanic-sedimentary basin of the Altay orogenic belt. Vein-shaped orebodies are hosted in the Kangbutiebao Formation and controlled by the NW-trending faults. In order to investigate the origin of ore-forming fluid and metal, a series of S-Pb-Sr-Nd-C-H-O isotopic analysis was carried out. According to field work and microscopic observation, the mineralization stages of the Wulasigou Cu deposit can be divided into pyrite-magnetite-quartz, chalcopyrite-chlorite-epidote-quartz and quartz-carbonate stages. The δ34S values of sulfide samples in this deposit are 0.1‰-3.2‰ (average:1.6‰), falling into the range of the δ34S values of wall rocks (-4.7‰-18.68‰), indicating that sulfur may be mainly derived from the Kangbutiebao Formation. The calcite sample shows δ13CV-PDB‰=-1.1‰ and δ18OV-PDB‰=-20.3‰, indicating that the marine carbonate strata and organic carbon are probably the sources of carbon. The Pb isotopes of eight pyrite samples are 206Pb/204Pb=17.939-18.508 (average 18.255), 207Pb/204Pb=15.519-15.674 (average 15.578), 208Pb/204Pb=37.881-38.653 (average 38.209), similar to those of the Kangbutiebao Formation. The ISr(220 Ma) values of pyrite are 0.710 4-0.711 7 (average 0.711 1), with initial 143Nd/144Nd values of 0.512 002-0.512 240 (average 0.512 103). The Sr-Nd-Pb isotopic compositions indicate that the metal sources of Wulasigou Cu deposit may be mainly from the Kangbutiebao Formation but with additional minerals. The δDV-SMOW values of the fluid range from -103.8‰ to -92‰ (average -99.2‰), the δ18OV-SMOW values for quartz and calcite are concentrated at 9.4‰-11.5‰ (average 10.4‰), and the δ18OH2O values range from 2.1‰ to 4.2‰ (average 3.1‰), indicating that the hydrothermal fluids may be originated from metamorphic water with the effect of meteoric water combined with physical and chemical characteristics of fluid inclusions. The metallogenic material of the Wulasigou Cu deposit is mainly derived from the metamorphic devolatilization of the host rock, which is consistent with the ore-forming mechanism of the orogenic deposit. |
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