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J4 ›› 2010, Vol. 16 ›› Issue (4): 448-456.

• 岩石学与矿床学 • 上一篇    下一篇

西藏邦铺大型钼铜多金属矿床Rb-Sr等时线年龄及地质意义

周雄, 温春齐, 张学全, 曹盛远, 吴鹏宇, 周玉, 费光春   

  1. 1. 成都理工大学 地球科学学院,成都  610059;2. 中国地质科学院 矿产综合利用研究所,成都  610041;
    3. 西藏地勘局 地热地质大队,拉萨 850000;4. 四川省地质矿产开发局 109地质队,龙泉  610100
  • 收稿日期:2010-07-07 修回日期:2010-09-27 出版日期:2010-12-20 发布日期:2010-12-20
  • 通讯作者: 温春齐,男,1945年生,博士,教授,博士生导师;
  • 作者简介:周雄,男,1979年生,博士研究生,矿物学、岩石学、矿床学专业;E-mail:zhouxiong27@163.com;
  • 基金资助:

    “十一五”国家科技支撑计划项目(2006BAB01A04);成都理工大学矿物学、岩石学、矿床学国家重点(培育)学科建设项目(SZD0407);中国地质科学院矿产综合利用研究所青年基金(D0701S-3)联合资助

Rb-Sr Isochron Age Dating of the Bangpu Large-Scale Mo-Cu Polymetallic Deposit, Tibet and Its Geological Significance

ZHOU Xiong,WEN Chun-qi,ZHANG Xue-quan,CAO Sheng-yuan,WU Peng-yu,ZHOU Yu,FEI Guang-chun   

  1. 1. School of Geosciences, Chengdu University of Technology, Chengdu  610059, China;2. Institute of Multipurpose Utilization of Mineral Resources, Chinese Academy of Geological Sciences, Chengdu 610041, China;3. Team of Geothermy and Geology, Tibet Bureau of Mineral Resource Exploration, Lhasa 850000, China;4. Geological Team No.109, Sichuan Bureau of Geology and Mineral Resources, Longquan 610100, China
  • Received:2010-07-07 Revised:2010-09-27 Online:2010-12-20 Published:2010-12-20

摘要:

       西藏邦铺钼铜多金属矿床是西藏冈底斯斑岩铜矿带东段典型的大型斑岩型矿床,以钼、铜为主,共生铅、锌。本文通过二长花岗斑岩全岩 Rb-Sr 法和含钼铜矿石中的黄铁矿 Rb-Sr 等时线法,分别获得等时线年龄为(13.88±0.38)Ma (MSWD=1.7)和(11.0±1.5)Ma(MSWD=3.5),代表二长花岗斑岩成岩、钼铜晚阶段的成矿年龄,结合锆石 SHRIMP U-Pb年龄(13.9±0.3)Ma 及含钼铜脉石英激光显微探针40Ar-39Ar 年龄(13.9±0.9)Ma,显示邦铺钼铜多金属矿床成岩、成矿年龄具有一致性,成矿时间持续约 3 Ma。锶同位素初始值(0.706538~0.709190)及幔源成分(Pm)含量(4.03%~51.65%)暗示邦铺二长花岗斑岩原始岩浆可能来自地幔,在冈底斯伸展构造背景下就位(14 Ma 前),幔源岩浆和硅铝质地壳物质发生交换并遭受地壳物质混染,以幔源物质为主,壳源物质为辅。

关键词: Rb-Sr等时线, 二长花岗斑岩, 黄铁矿, 钼铜多金属矿床, 西藏邦铺

Abstract:

         The Bangpu Mo-Cu polymetallic deposit is one of the typical large-scale porphyry deposits which lies in the eastern Gangdese metallogenic belt, Tibet. Its major  ore elements are molybdenum and copper, and its accompanying elements are lead and zinc. A monzonite granite-porphyry whole-rock Rb-Sr isochron age of (13.88±0.38) Ma with MSWD=1.7 was obtained which represents the crystallization age of the rock. Furthermore, a pyrite Rb-Sr isochron age of (11.0±1.5) Ma with MSWD=3.5 was obtained for Mo and Cu bearing ores which represents the age of later episode of Mo-Cu mineralization. Combining with the zirconSHRIMP U-Pb age (13.9±0.3) Ma and laser micro-probe 40Ar-39Ar age (13.9±0.9) Ma, it is shown that the rock-forming and ore-forming ages are mutually consistent. The molybdenum and copper mineralization lasted about 3 Myrs. The inital 87Sr/ 86Sr valu(0.706538~0.709190) and mantle composition percentage (Pm) (4.03%~ 51.65%) indicate that the primary magma might be derived from the mantle, and emplaced in the Gangdese extensional setting 14 Myrs ago. The mantle magma was interacted with crustal dioritic magma and contaminated by crustal materials during its ascending process. But generally speaking, the magma source was mainly mantle-derived.

 

Key words: Rb-Sr isochron, monzonite granite-porphyry, pyrite, Mo-Cu polymetallic deposit, Bangpu of Tibet

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