汉南地区晋宁晚期铜-金成矿事件的确认及意义  

Identification of Late Jinning period Cu-Au mineralization event in Hannan region and its significance

作　　者：崔建军[1] 曲玮[1] 高福平 郑光高[1] 赵文平 陈龙耀[1] 李淼[1] 刘林 于新兵[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]陕西省地质矿产勘查开发总公司第二分公司,陕西汉中723000 [3]陕西矿业开发工贸公司,陕西西安710054 [4]陕西省矿产资源勘查与综合利用重点实验室,陕西西安710054

出　　处：《矿床地质》2017年第3期659-674,共16页Mineral Deposits

基　　金：陕西省矿产资源勘查与综合利用重点实验室基金(编号:2014-01);地质力学研究所基本科研业务费(编号:DZLXJK201302);地质调查项目钦杭结合带及邻区深部地质调查项目(编号:121201104000160916);国土资源部公益性行业科研专项经费资助(编号:201311036-02);国家自然科学基金项目"川东北双弧构造形成机理"(编号41172184)联合资助

摘　　要：汉南地区位于扬子克拉通北缘西段。目前,在川、陕两省已在该区发现了数十个矿床(点)。其中,广泛分布的铜-金矿床(点)具有热液型矿化特征,成矿条件有利,具有寻找大-中型矿床的远景。为了查明这些铜-金矿产资源的形成时代,文章运用LA-ICP-MS锆石U-Pb法和单矿物^(40)Ar/^(39)Ar法对汉南地区有代表性的矿床(点)进行了成矿年代学研究。其结果显示,潘坝成矿期热液脉的锆石U-Pb年龄为(744±10)Ma,黑云母和钾长石^(40)Ar/^(39)Ar视年龄介于740 Ma^700 Ma之间。元山寺的成矿期白云母^(40)Ar/^(39)Ar坪年龄为(744±4)Ma,等时线年龄为(748±7)Ma。由于本次测试选择了成矿期矿物,其结果可以代表成矿时代。因此,汉南很可能存在晋宁晚期的铜-金成矿事件。根据区域地质演化历史,笔者认为汉南铜-金矿化(744 Ma)是造山晚期加厚岩石圈下部(山根)拆沉的结果。The Hannan region is located in the western part of the northern margin of the Yangtze craton. Up till now, geological exploration departments of Shaanxi and Sichuan Provinces have discovered dozens of ore deposits （ore spots） in this region. Among them, Cu-Au deposits are widely distributed and characterized by hydrothermal mineralization, favorable metallogenic conditions, and the prospect of finding large and medium-sized deposits. To determine the metallogenic epoch of the Cu-Au mineralization in the Hannan region, the authors investigated the metallogenic chronology of two typical deposits. The results show that the zircon U_Pb age for Cu-Au mineralized hydrothermal veins at Panba Village is （744±10） Ma, while the ages of the biotite and potassium feldspar of these hydrothermal veins, based on ^40Ar/^39Ar age spectrum results, range between 740 Ma and 700 Ma. The ^40Ar/^39Ar plateau age of muscovite in the mineralized granite at Yuanshansi is （744±4） Ma, and the isochron age is （748±7） Ma. As the survey tests were performed on the minerals of the mineralization period, the results obtained are likely to represent the metallogenic epoch of Cu-Au deposits. The Cu_Au hydrothermal mineralization events are proved to have happened probably in the Late Jinning period in Hannan region. According to the evolution history of regional geology, the authors hold that Cu_Au mineralization （744 Ma） in Hannan was induced by the delamination in the lower part of the lithosphere of the orogenic belt on the northwestern margin of the Yangtze Craton. According to data available, the dynamic background and influencing range of the mineralization in this epoch have been discussed.

关 键 词：地球化学 锆石U-PB年代学 ^40AR/^39AR年代学 晋宁晚期 铜-金成矿事件 汉南地区 

分 类 号：P618.41[天文地球—矿床学] P618.51[天文地球—地质学]