| 西秦岭温泉斑岩钼矿床岩浆-热液演化 |
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| 引用本文： | 邱昆峰,宋开瑞,宋耀辉.西秦岭温泉斑岩钼矿床岩浆-热液演化[J].岩石学报,2015,31(11):3391-3404. |
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| 作者姓名： | 邱昆峰 宋开瑞 宋耀辉 |
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| 作者单位： | 中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083;美国地质调查局丹佛中心, 丹佛 80225,中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083,中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083;核工业航测遥感中心, 石家庄 050000 |
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| 基金项目： | 本文受国家重点基础研究发展规划(2015CB452605)、中国地质调查局地质调查项目(1212011121090)、111计划(B07011)、国家留学基金和Society of Economic Geologists Foundation联合资助. |
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| 摘 要： | 西秦岭北缘广泛出露印支期中酸性侵入岩和相关的斑岩-矽卡岩矿床。温泉矿床位于该矿带东段,是其内已探明规模最大的斑岩钼矿床。温泉矿床发育多阶段热液脉体,黄铁矿作为其中的贯通性金属硫化物,其化学组成蕴含着岩浆-热液演化及金属沉淀过程等诸多信息,对于斑岩系统模型的厘定具有重要意义。温泉矿床热液脉体时序为:钾长石-黑云母-石英脉(A脉)、石英-黄铜矿脉、石英-辉钼矿脉(B脉)和石英-绢云母-黄铁矿脉(D脉)。A脉是斑岩系统岩浆-热液演化的最早期脉体,主要矿物组合为钾长石+黑云母+石英+黄铁矿±磁铁矿±磷灰石±黄铜矿,代表了引起早期基性岩浆矿物被蚀变为黑云母的流体通道;B脉与钾长石化蚀变关系密切,围岩中斜长石斑晶大量被蚀变为钾长石;石英-辉钼矿脉切割所有早期黑云母化-钾化蚀变阶段的石英-硫化物网脉,并形成于所有斑岩侵位之后,少量黄铁矿和黄铜矿共生于辉钼矿裂隙及边部;D脉是斑岩系统岩浆-热液成矿作用的最晚期事件,其主要被黄铁矿和石英及少量黄铜矿填充,发育晚期的绢英岩化和泥化蚀变,长石多发生破坏性蚀变。四个阶段石英网脉中黄铁矿电子探针分析显示,A脉的黄铁矿中Cu、Mo和Au含量均较低,有少量的金属硫化物(黄铁矿+黄铜矿)沉淀,但通常不能形成规模矿体;石英-黄铜矿脉的黄铁矿中Cu含量明显较高,且多与高品位Cu矿体的空间产出位置相一致,可能是斑岩系统伴随钾化蚀变作用主要的铜沉淀阶段;B脉的黄铁矿中Mo含量明显较高,与高品位钼矿体空间产出关系密切,可能代表了斑岩系统钼成矿作用的主要阶段;D脉的黄铁矿中Au含量明显升高,可能代表了金在斑岩系统岩浆-热液成矿作用的最晚期事件中的沉淀。
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| 关 键 词： | 岩浆-热液作用 石英网脉 黄铁矿 微量元素 温泉矿床 西秦岭 |
| 收稿时间： | 2015/4/1 0:00:00 |
| 修稿时间： | 2015/6/17 0:00:00 |
Magmatic-hydrothermal fluid evolution of the Wenquan porphyry molybdenum deposit in the north margin of the West Qinling, China. |
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| QIU KunFeng,SONG KaiRui and SONG YaoHui.Magmatic-hydrothermal fluid evolution of the Wenquan porphyry molybdenum deposit in the north margin of the West Qinling, China.[J].Acta Petrologica Sinica,2015,31(11):3391-3404. |
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| Authors: | QIU KunFeng SONG KaiRui and SONG YaoHui |
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| Institution: | State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;Denver Federal Center, U. S. Geological Survey, Denver 80225, USA,State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China and State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;Airborne Survey and Remote Sensing Center of Nuclear Industry, Shijiazhuang 050000, China |
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| Abstract: | The Indosinian granitoids, widely distributed in the northern margin of the West Qinling, are closely associated with the porphyry and skarn deposits spatio-temporally. The Wenquan large porphyry deposit, located in the Tianshui region, is characterized by low-grade molybdenum mineralization developed within and around porphyries and related to pervasive hydrothermal alteration zones. Pyrite, a ubiquitous mineral and a major constituent of porphyry stockwork veins at the Wenquan deposit. Study on chemical composition of pyrite could provide more constraints on fluid evolution and metal precipitation of magmatic-hydrothermal mineralization. 42 samples recording the sequence of vein formation independently were collected in numerous observation points throughout the deposit, based on intersection and overprinting relationships between different veins (veinlets), intrusive contacts, and alteration types (halos), four quartz stockwork veins are distinguished, as quartz-k-spar-biotite vein (A-veinlet), quartz-chalcopyrite vein, quartz-molybdenite vein (B vein) and quartz-sericite-pyrite vein (D vein). The concentrations of Cu, Mo and Au of 101 pyrite grains in a suite of samples of four types quartz stockwork veins at Wenquan were determined by electron microprobe analysis (EMPA), indicating that, A-veinlets, the earliest vein type recognized in magmatic-hydrothermal mineralization, are associated with biotite stable alteration, and represent the channel-ways for fluid causing alteration of former mafic minerals to biotite. Low concentrations of Cu, Mo and Au are detected in pyrites consistent to the fact that few sulfides precipitated during this stage. Quartz-chalcopyrite veins are closely related with potassic alteration with alteration of plagioclase to K-feldspar, and high Cu concentration of pyrite indicates the main stage of Cu mineralization. B veins, with higher Mo concentration of pyrite, as well as closely related to high grade Mo orebodies spatially, represent the main Mo mineralization stage. D veins, cutting and overprinting earlier quartz veins and cut by cracks filled with kaolinite and clays, as the last event of magmatic-hydrothermal mineralization, are filled mainly with pyrite and minor chalcopyrite and quartz, and closely associated with seritic alteration, which represent the Au and later Cu deposition stage. |
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| Keywords: | Magmatic-hydrothermal mineralization Quartz stockwork veins Chemical composition Pyrite Wenquan deposit West Qinling |
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