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华南地区中生代主要金属矿床时空分布规律和成矿环境

毛景文1,谢桂青1,郭春丽1,袁顺达1,程彦博2,陈毓川1   

  1. 1. 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;2. 中国地质大学 地球科学与资源学院,北京,100029
  • 收稿日期:2008-12-20 修回日期:2008-12-20 出版日期:2008-12-20 发布日期:2008-12-20

Spatial-Temporal Distribution of Mesozoic Ore Deposits in South China and Their Metallogenic Settings

MAO Jing-wen1, XIE Gui-qing1, GUO Chun-li1, YUAN Shun-da1, CHENG Yan-bo2, CHEN Yu-chuan1   

  1. 1. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources,Chinese Academy of Geological Sciences, Beijing 100037,China;2. Faculty of Earth Sciences, China University of Geosciences, Beijing 100029, China
  • Received:2008-12-20 Revised:2008-12-20 Online:2008-12-20 Published:2008-12-20

摘要: 以广泛地质调查和放射性同位素年龄精测数据为基础,总结提出了华南地区中生代主要金属矿床成矿出现于三个阶段,即晚三叠世(230~210 Ma)、中晚侏罗世(170~150 Ma)和早中白垩世(134~80 Ma)。晚三叠世矿化组合为钨锡铌钽;中晚侏罗世的矿化组合进一步分为170~160 Ma斑岩-矽卡岩铜矿和160~150 Ma与花岗岩有关的钨锡多金属矿床;白垩纪矿化虽然持续了54 Ma,但主要峰期在100~90 Ma,主要矿化组合为浅成低温热液型铜金银矿床和花岗岩有关的钨锡铜多金属矿床。晚三叠世钨锡铌钽矿化成因上与过铝质二云母花岗岩有关,是华北、华南和印支三大板块后碰撞过程的成岩成矿响应。在180 Ma左右Izanagi板块向欧亚大陆俯冲,于170~160 Ma期间可能由于俯冲板片局部多处撕裂而形成Ⅰ型或埃达克质岩石和有关的的斑岩铜矿,紧接着在南岭地区于160~150 Ma期间俯冲板块开天窗,软流圈物质直接涌入上地壳,形成了一种壳幔混合型高分异花岗质岩石及其钨锡多金属矿床。在135 Ma左右由于俯冲板块改变了运动方向,由斜向俯冲调整到几乎平行大陆边缘沿NE方向走滑,造成大陆岩石圈大面积伸展而形成了大量白垩纪断陷盆地和变质核杂岩,并伴随大规模的火山活动和花岗质岩浆侵位及其浅成低温热液铜金银矿化系统、与花岗岩有关的钨锡多金属矿化系统和热液型铀矿的形成。

Abstract: Based on extensive field investigation and precise geochronological data we proposed Mesozoic metallic mineralization in South China can be grouped into three pulses, i.e. Late Triassic (230~210 Ma), Mid-Late Jurassic (170~150 Ma), and Early-Middle Cretaceous (134~80Ma). The mineralization elements in these three pulses are different. The Triassic mineralization is Peraluminous granite-related W-Sn-Nb-Ta. The Mid-late Jurassic mineralization can be further divided into 170~160 Ma porphyry and skarn Cu and I-type granite-related Pb-Zn-Ag, and 160~150 Ma paraluminous granite-related polymetallic W-Sn. Although the Cretaceous mineralization lasted about 54 Ma, its peak ranged from 100 Ma to 90 Ma. The major types of the mineralization are epithermal Au-Ag-Cu and granite-related polymetallic tin (tungsten). The Triassic peraluminous granite-related W-Sn-Nb-Ta is a response to the post-collisional process of the South China plate with the North China plate. The Izanagi plate started to subduct beneath the Eurasian continent at ca. 180 Ma and then the porphyry copper deposits and vein type Pb-Zn-Ag deposits and their related I-type granitoids or aidakitic rocks formed when the subducted plate was teared up in several locations at 170~160 Ma.After then a big window occurred in the Nanling area, triggering the asthenospheric substance got into the upper crust so that developed large-scale high fractionation paraluminous granite and related polymetallic W-Sn mineralization. It was a relatively quiet period of 150~135 Ma in South China except for the Middle-Lower Yangtze River Valley area located in the northeastern margin of the South China plate. Because starting to change motion-direction to northeast the subucted plate was teared up along the Middle-Lower Yangtze River Valley which used to be a foreland basin of the Triassic Dabie-Sulu orogenic belt. A group of skarn-porphyry Cu-Mo-Au-Fe ore system and related I-type or aidakitic granites developed along the cross of the Middle-Lower Yangtze River Valley with the NE-trending faults at an age range of 145~135 Ma. From 135 Ma the subducted plate moved along several groups of regional-scale NE-striking fault zones comprising the Tan-Lu fault zone, which trigged the Eurasian continent to extensive extension. At the setting developed a lot of linear NE-trending Cretaceous faulting basins and metamorphic cores accompanied with volcanic rock eruption as well as epithermal Cu-Au-Ag ore system, granite-related polymetallic Sn (W) deposits and hydrothermal uranium deposits at age of 120~80 Ma with a peak of 100~90 Ma.