| 安徽新桥矿床矿相学与Fe同位素特征及其对矿床成因的制约 |
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| 引用本文： | 王跃,朱祥坤,程彦博,李志红.安徽新桥矿床矿相学与Fe同位素特征及其对矿床成因的制约[J].吉林大学学报(地球科学版),2013,43(6):1787. |
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| 作者姓名： | 王跃 朱祥坤 程彦博 李志红 |
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| 作者单位： | 1.中国地质科学院地质研究所/国土资源部同位素地质重点实验室/大陆构造与动力学国家重点实验室，北京100037;
2.中国地质科学院矿产资源研究所/国土资源部成矿作用与资源评价重点实验室，北京100037 |
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| 基金项目： | 国家自然科学基金;国土资源部公益性行业科研专项;国家重点基础研究发展计划（973计划）;基本科研业务费项目 |
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| 摘 要： | 对安徽新桥矿床进行系统的野外地质调查和矿相学研究发现，层状矿体中的胶状黄铁矿交代矽卡岩磁铁矿矿体，为探讨层状硫化物矿床是早期沉积成因还是岩浆热液成因提供了新的地质约束。对铜陵矿集区内的新桥矿床层状菱铁矿矿体和凤凰山矽卡岩型矿体中的菱铁矿开展了Fe同位素组成的对比研究，结果显示：新桥矿床菱铁矿与典型低温热液脉型矿床和沉积铁矿中的菱铁矿在Fe同位素组成特征上有所不同，而与凤凰山矽卡岩型矿床中的菱铁矿更为接近；新桥矿床中胶状黄铁矿和菱铁矿相对于磁铁矿富集Fe的轻同位素，表明磁铁矿不是过去认为的由胶状黄铁矿和菱铁矿矿胚层经热液改造形成，而是与典型的岩浆热液有关。新桥矿区层状硫化物矿体和矽卡岩型矿体中，近岩体矽卡岩和最早形成的金属矿物磁铁矿比岩体更为富集Fe的轻同位素，而赋矿围岩比岩体更为富集Fe的重同位素。同时，不同矿化阶段形成的含铁矿物和不同空间位置的硫化物中的Fe同位素组成呈现出时空分带现象，Fe同位素组成的时空演化特征与流体出溶、流体演化非常一致，并且符合同位素分馏的基本理论，表明层状硫化物矿体和矽卡岩型矿体具有相同的成矿物质来源，为同一流体体系演化的产物。新桥矿区岩相学的研究结果和Fe同位素组成特征均表明，新桥层状硫化物矿床不是海西期喷流沉积成矿作用的产物，而是燕山期热液成矿作用的产物，为一个典型的热液成因矿床。
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| 关 键 词： | 新桥矿床 矿相学 菱铁矿 Fe同位素 矿床成因 |
| 收稿时间： | 2013-05-12 |
Ore Microscopy & Fe Isotope of the Xinqiao Deposit and Their Constraints on the Ore Genesis |
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| Wang Yue,Zhu Xiangkun,Cheng Yanbo,Li Zhihong.Ore Microscopy & Fe Isotope of the Xinqiao Deposit and Their Constraints on the Ore Genesis[J].Journal of Jilin Unviersity:Earth Science Edition,2013,43(6):1787. |
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| Authors: | Wang Yue Zhu Xiangkun Cheng Yanbo Li Zhihong |
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| Institution: | 1.Institute of Geology, Chinese Academy of Geological Sciences/Laboratory of Isotope Geology, MLR/State Key Laboratory for Continental Tectonics and Dynamics, Beijing100037, China;
2.Institute of Mineral Resources, Chinese Academy of Geological Sciences/MLR Key Laboratory of Metallogeny and Mineral Assessment, Beijing100037, China |
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| Abstract: | Systematical field work and ore microscopy studies have been carried out in the Xinqiao deposit. The fact that the skarn-associated magnetite is cut by the colloidal pyrite in the stratiform ore body provides a new constraint on the ore genesis of the stratiform sulfide ore body in Xinqiao deposit. The Fe isotope compositions of siderite minerals from the siderite ore bodies in Xinqiao and Fenghuagnshan skarn Fe-Cu ore bodies were analyzed and compared. Fe isotope compositions of the siderite from Xinqiao deposit are different from those from sedimentary and hydrothermal vein-type deposits, but similar to those from the Fenghuanghsan skarn Fe-Cu deposit. Moreover, the fact that the heavy Fe isotope enrichment in magnetite related to siderite and colloidal pyrite indicates that the siderite and colloidal pyrite cannot be altered to be magnetite. Fe isotope compositions in sulfide ores, quartz-monzodiorite stock and limestone wall-rock in Xinqiao strata bound sulfide and skarn ore were examined. The δ57Fe values of endoskarn and the earliest formed magnetite are lower than those of the quartz-monzodiorite, while δ57Fe values of limestone wall-rock are higher than those of the igneous stock. Moreover, such features as spatial and temporal zoning, evolution of Fe isotope are consistent with fluid exsolutionary and evolutionary theory, also accordant with basic theory of Fe isotopic fractionation, which suggests that two types of ores be resulted from the same hydrothermal fluid system and Fe element came from the same magmatic source. The Fe isotope characteristics, together with ore minerals paragenesis relationship, demonstrate that the Xinqiao Cu-S-Fe-Au deposit is a typical hydrothermal skarn deposit, rather than the multi-stage syngenetic-hydrothermal compound deposit. |
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| Keywords: | Xinqiao deposit ore microscopy siderite Fe isotope ore genesis |
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