地学前缘 ›› 2019, Vol. 26 ›› Issue (5): 17-32.DOI: 10.13745/j.esf.sf.2019.9.15

• 区域成矿作用 • 上一篇    下一篇

西秦岭夏河—合作地区与还原性侵入岩有关的金成矿系统及其动力学背景和勘查意义

李建威，隋吉祥，靳晓野，文广，昌佳，朱锐，詹涵钰，武文辉   

  1. 1. 地质过程与矿产资源国家重点实验室; 中国地质大学(武汉) 资源学院, 湖北 武汉 430074
    2. 甘肃招金矿业有限公司 早子沟金矿, 甘肃 合作 747000
    3. 四川省地质调查院, 四川 成都 610081
  • 收稿日期:2018-06-10 修回日期:2019-05-28 出版日期:2019-09-28 发布日期:2019-09-28
  • 作者简介:李建威(1969—)，男，教授，博士生导师，主要从事矿床学研究。 E-mail:jwli@cug.edu.cn
  • 基金资助:
    国家自然科学基金项目(41802091, 41772081, 41072057)；中央高校基本科研业务费专项资金项目(CUGCJ1711)

The intrusion-related gold deposits in the XiaheHezuo district, West Qinling Orogen: geodynamic setting and exploration potential.

LI Jianwei，SUI Jixiang，JIN Xiaoye，WEN Guang，CHANG Jia，ZHU Rui，#br# ZHAN Hanyu,WU Wenhui   

  1. 1. State Key Laboratory of Geological Processes and Mineral Resources; School of Earth Resources, China University of Geosciences(Wuhan), Wuhan 430074, China
    2. Zaozigou Gold Mine, Zhaojin Mining Industry Co. LTD., Hezuo 747000, China
    3. Sichuan Geological Survey, Chengdu 610081, China
  • Received:2018-06-10 Revised:2019-05-28 Online:2019-09-28 Published:2019-09-28

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摘要： 西秦岭造山带是我国最重要的金成矿带之一。以往研究大多认为造山型金矿床和(类)卡林型金矿床是西秦岭主要的金矿床类型，并且两类金矿床的金成矿作用主要与造山过程中的区域变质作用有关，而与岩浆活动不存在直接的成因联系。位于西秦岭造山带西段的夏河—合作地区大面积出露花岗岩类侵入体，其周缘发育有富金的夕卡岩型铜(钨)矿床。近年来该地区新发现的多个大型—超大型石英脉型金矿床和微细粒浸染型金矿床都与中酸性侵入岩的空间关系紧密，暗示这些金矿床可能和岩浆活动有成因联系。论文在作者研究结果以及总结前人成果基础上，综述了夏河—合作地区典型金(铜)矿床的地质矿化特征、地球化学特征、时空分布特征，以及中酸性侵入岩的岩性特征、形成时代和演化过程。年代学研究结果显示，夏河—合作地区的早子沟微细粒浸染型金矿床、德乌鲁夕卡岩型金(铜)矿床和老豆石英脉型金矿床均形成于250~240 Ma，与邻近的早中三叠世花岗闪长质石英闪长质侵入岩近于同时形成。拉布在卡等石英脉型金矿床略晚于区内中三叠世末期侵位的闪长玢岩脉(约230~225 Ma)形成。H、O、S、C、B、Pb等多种同位素地球化学特征指示该地区早中三叠世金矿床的成矿热液均为岩浆来源，并且显示低氧逸度的特征。早中三叠世中酸性侵入岩的还原性钛铁矿系列花岗岩类特征，以及同时代的多种金矿化类型和成矿分带性，表明夏河—合作地区在早中三叠世(约250~230 Ma)多期次侵位的钛铁矿系列I型中酸性岩浆是金成矿作用的成矿流体和成矿物质的主要来源，其中与250~240 Ma多期金成矿事件有关的准铝质弱过铝质、高钾钙碱性系列花岗岩类侵入岩均经历了幔源基性熔体和壳源酸性熔体的岩浆混合作用，而与约230 Ma的金成矿作用有关的闪长质岩浆岩则可能指示了更多幔源基性熔体的加入。与金(铜)成矿有关的早中三叠世还原性中酸性岩是在古特提斯洋俯冲过程中局部弧后伸展条件下交代富集地幔楔部分熔融形成的基性岩浆与壳源酸性岩浆混合作用的产物。夏河—合作地区形成于早中三叠世的夕卡岩型、电气石石英脉型、石英方解石脉型和微细粒浸染型金矿床共同构成了一个与还原性侵入岩有关的金成矿系统。夏河—合作地区与还原性侵入岩有关的金成矿系统的发现，丰富了西秦岭造山带区域成矿作用的类型，并为西秦岭西段其他早中三叠世岩浆岩分布区(如青海同仁地区)的金矿勘查工作提供了新的思想和方向。

关键词: 西秦岭；夏河&mdash, 合作地区；与还原性侵入岩有关的金矿；早中三叠世；金成矿系列

Abstract: The West Qinling Orogen is well endowed with numerous orogenic and Carlin-like type gold deposits. Most of previous studies suggested that the ore-forming fluids of these gold deposits were derived from metamorphic devolatilization of the Paleozoic marine sedimentary sequences during the Triassic continental collision forming the Qinling Orogen. The XiaheHezuo district in the western portion of the West Qinling Orogen has been becoming a major exploration interest in the last decade due to discovery of numerous gold deposits. Most gold deposits of various mineralization styles in the district are spatially associated with intermediate to felsic intrusions, but their geneses remain poorly understood. Based on previous studies as well as our present works, we summarized here the geological and geochemical features of various types of gold deposits, including skarn Au-Cu deposit, tourmaline-quartz vein-type gold deposit, quartz-calcite vein-type gold-polymetallic deposit and country rock-hosted disseminated type gold deposit. We then reviewed the petrogenesis and tectonic implication of associated granitoid intrusions. We suggest that multiple magmatic hydrothermal gold mineralizing events took place in the XiaheHezuo district, and these events are genetically associated with ilmenite-series intermediate to felsic magmatism during the early to middle Triassic (ca. 250230 Ma). These deposits combined form the first reduced intrusion-related gold system in the West Qinling Orogen. This work indicates an early to middle Triassic magmatic hydrothermal gold mineralization event in the West Qinling Orogen, and in its west portion it may discover another reduced intrusion-related gold deposit.

Key words:  West Qinling, XiaheHezuo district, reduced intrusion-related gold deposit, early to middle Triassic, gold mineralization system

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