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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。
Hannan is located in the western section of the northern edge of the Yangtze craton. At present, dozens of deposits (spots) have been discovered in the two provinces of Sichuan and Shaanxi. Among them, widely distributed copper-gold deposits have hydrothermal mineralization features, favorable metallogenic conditions and the prospect of finding large-medium-sized deposits. In order to find out the formation age of these copper-gold mineral resources, the authors used the LA-ICP-MS zircon U-Pb method and the single mineral ~ (40) Ar / ~ (39) Ar method to characterize the representative deposits in Hannan area (Point) conducted a metallogenic chronology. The results show that the zircon U-Pb ages of the hydrothermal veins in Panba were (744 ± 10) Ma and that of biotite and feldspar ~ (40) Ar / ~ (39) Ar were between 740 Ma ~ 700 Ma. The age of ~ (40) Ar / ~ (39) Ar plateau of muscovite is (744 ± 4) Ma and the isochron age is (748 ± 7) Ma. Due to the selection of mineralization mineral during this test, the result can represent the mineralization era. Therefore, Hannan is likely to have the late Jinning copper-gold mineralization event. According to the history of regional geological evolution, the authors believe that the Han-Han copper-gold mineralization (744 Ma) is the result of thickening of the lower part of the lithosphere (mountain root) detachment in the late orogenic period.