| 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 |
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| 引用本文： | 周雄,温春齐,张学全,曹盛远,吴鹏宇,周玉,费光春.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[J].高校地质学报,2010,16(4):448-456. |
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| 作者姓名： | 周雄 温春齐 张学全 曹盛远 吴鹏宇 周玉 费光春 |
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| 作者单位： | 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 |
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| 基金项目： | "十一五"国家科技支撑计划项目，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，中国地质科学院矿产综合利用研究所青年基金 |
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| 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SHRIMPU-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3Ma。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(14Ma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。
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| 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 |
| 修稿时间： | 2010-09-27 |
Rb-Sr Isochron Age Dating of the Bangpu Large-Scale Mo-Cu Polymetallic Deposit, Tibet and Its Geological Significance |
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| ZHOU Xiong,WEN Chun-qi,ZHANG Xue-quan,CAO Sheng-yuan,WU Peng-yu,ZHOU Yu,FEI Guang-chun.Rb-Sr Isochron Age Dating of the Bangpu Large-Scale Mo-Cu Polymetallic Deposit, Tibet and Its Geological Significance[J].Geological Journal of China Universities,2010,16(4):448-456. |
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| Authors: | ZHOU Xiong WEN Chun-qi ZHANG Xue-quan CAO Sheng-yuan WU Peng-yu ZHOU Yu FEI Guang-chun |
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| Institution: | 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 |
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| Abstract: | The Bangpu Mo-Cu polymetallic deposit is one of the typical large-scale porphyry deposits which lies in the easternGangdese metallogenic belt, Tibet. Its major ore elements are molybdenum and copper, and its accompanying elements are leadand zinc. A monzonite granite-porphyry whole-rock Rb-Sr isochron age of (13.88±0.38) Ma with MSWD=1.7 was obtained whichrepresents the crystallization age of the rock. Furthermore, a pyrite Rb-Sr isochron age of (11.0±1.5) Ma with MSWD=3.5 wasobtained 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 andore-forming ages are mutually consistent. The molybdenum and copper mineralization lasted about 3 Myrs. The inital 87Sr/ 86Srvalu（0.706538~0.709190） and mantle composition percentage (Pm) (4.03%~ 51.65%) indicate that the primary magma mightbe derived from the mantle, and emplaced in the Gangdese extensional setting 14 Myrs ago. The mantle magma was interactedwith crustal dioritic magma and contaminated by crustal materials during its ascending process. But generally speaking, themagma source was mainly mantle-derived. |
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