地学前缘 ›› 2020, Vol. 27 ›› Issue (2): 151-164.DOI: 10.13745/j.esf.sf.2020.3.16

• 特色地域成矿背景与成矿作用 • 上一篇    下一篇

扬子西缘陆内构造转换系统与构造岩浆成矿效应

李文昌,江小均   

  1. 1. 中国地质调查局 成都地质调查中心, 四川 成都 610081
    2. 昆明理工大学 国土资源工程学院 地球科学系, 云南 昆明 650093
  • 收稿日期:2020-01-02 修回日期:2020-02-03 出版日期:2020-03-25 发布日期:2020-03-25
  • 作者简介:李文昌(1962—),男,博士,教授级高级工程师,主要从事找矿勘探和矿床地质研究。E-mail:lwcyndd@163.com
  • 基金资助:

    国家重点基础研究发展计划“973”项目(2015CB452606);云南省科技领军人才培养计划项目(2013HA001);云南省应用基础研究计划青年项目(2016DF031)

The Cenozoic tectonomagmatismmineralization effect of the intracontinental tectonic transformation system in the western margin of Yangtze Block

LI Wenchang,JIANG Xiaojun   

  1. 1. Chengdu Geological Survey Center, China Geological Survey, Chengdu 610081, China
    2. Department of Earth Sciences, Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China
  • Received:2020-01-02 Revised:2020-02-03 Online:2020-03-25 Published:2020-03-25

摘要:

横跨欧亚呈东西延伸的特提斯构造域是全球最重要的有色贵金属成矿带之一,该带向东到达扬子陆块后转向东南,位于转折部位的扬子西缘近年发现系列大型超大型Cu-Au矿床。以往认为,扬子西缘金沙江—红河大型走滑断裂切穿岩石圈,诱发岩浆上侵,形成富碱斑岩带。本文通过对扬子西缘剑川老君山、鹤庆北衙、姚安老街子—干沟、大姚吁支拉和永仁直苴等多个富碱岩体进行调查和构造应力分析,表明富碱斑岩在沿金沙江—红河断裂两侧分布的同时,也有大量岩体(脉)进入扬子板块内部,沿EW向断裂展布,其成岩成矿年龄为36.87~30.70 Ma,与富碱斑岩带一致,同时岩浆活动表现出由西向东时代变新,碱质增加等自西向东运移的特征;对近EW向岩体(脉)及节理的野外观测和统计分析表明,控岩构造具有东西挤压南北伸展的应力特征,与北西向大型走滑构造配套。由此提出,扬子陆块西缘新生代发育大规模陆内构造转化系统,陆块内部系列富碱岩浆,其形成与深切的NW向大型走滑构造有关,自西而东就位于派生的SN向、EW向次级构造,发育斑岩Cu-Au等成矿作用,成岩成矿与陆内构造转化系统耦合。

关键词: 扬子西缘, 新生代, 陆内构造转换系统, 富碱斑岩, 成矿效应

Abstract:

The Tethys tectonic domain, which extends from east to west across Eurasia, contains one of the most important precious/base metallogenic belts. The belt turns toward the southeast after reaching the Yangtze Block and series of large to giant Cu-Au deposits have recently been discovered at this hinge zone. It has previously been determined that the largescale JinshajiangHonghe strikeslip fault along the western Yangtze margin cut through the lithosphere, inducing magmatic intrusions and forming an alkalirich porphyry belt. In this study, several alkalirich intrusions (including Laojunshan in Jianchuan, Beiya in Heqing, LaojieziGangou in Yao’an, Yuzhila in Dayao, and Zhiju in Yongren) were analysed for tectonic stress. The results show that in addition to the distribution of alkalirich porphyries along both sides of the JinshajiangHonghe Fault, there are also many dykes along the E-W-trending structures within the interior of the Yangtze Block. These intrusions have magmatic and mineralization ages ranging from 36.87-30.70 Ma, coeval with the formation of the porphyry belt. It was found that the magmatic ages become younger and alkalinity increases from west to east, defining an eastward magmatic migration. Field observations and statistical analyses of these nearly E-W-trending dykes and joints revealed that the structures controlling magmatism have undergone E-W compression and N-S extension, which is compatible with the large NWtrending strikeslip structures observed. Based on these lines of evidence, the formation of a series of alkalirich intrusions within the Yangtze Block is likely related to the largescale NWtrending strikeslip structures. The alkalirich intrusions and related Cu-Au porphyry mineralization are distributed in the N-S and E-W-trending secondary structures from west to east, and magmatism and mineralization were coupled with intracontinental structural transformations.

Key words: western margin of Yangtze Block, Cenozoic, intracontinental tectonic transformation system, alkalirich porphyry, metallogenic effect

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