北京大学学报自然科学版 ›› 2017, Vol. 53 ›› Issue (4): 667-682.DOI: 10.13209/j.0479-8023.2017.009

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广西大宁岩体和初洞岩体锆石U-Pb年代学及Hf同位素研究

郭丽爽1,2,3, 吕鑫4, 王政华5, 毛佐国6, 张继林7, 刘玉琳3(), 陈旭8   

  1. 1. 中国地震局地壳应力研究所, 北京 100085
    2. 中国地震局地壳动力学重点实验室, 北京 100085
    3. 造山带与地壳演化教育部 重点实验室, 北京大学地球与空间科学学院, 北京 100871
    4. 中国地质调查局发展研究中心, 北京 100037
    5. 万宝矿产有限公司, 北京 100053
    6. 中国黄金集团公司贺州市金琪矿业有限责任公司, 贺州 542800
    7. 北京金有地质勘查有限责任公司, 北京 100070
    8. Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park, PA 16802
  • 收稿日期:2016-03-21 修回日期:2016-05-13 出版日期:2017-07-13 发布日期:2017-07-20
  • 基金资助:
    中国黄金集团勘查项目(KY2010-01)资助

Zircon Geochronology and Hf Isotopes of Daning and Chudong Intrusions, Guangxi Prvince

Lishuang GUO1,2,3, Xin LÜ4, Zhenghua WANG5, Zuoguo MAO6, Jilin ZHANG7, Yulin LIU3(), Xu CHEN8   

  1. 1. Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085
    2. Key Laboratory of Crustal Dynamics, China Earthquake Administration, Beijing 100085
    3. Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing 100871
    4. Development Research Center of China Geological Survey, Beijing 100037
    5. Wanbao Mining Ltd., Beijing 100053
    6. Jinqi Mining Ltd., China National Gold Group Corporation, Hezhou 542800
    7. Jinyou Geological Exploring Ltd., Beijing 100070
    8. Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park, PA 16802
  • Received:2016-03-21 Revised:2016-05-13 Online:2017-07-13 Published:2017-07-20

摘要:

利用锆石LA-ICP-MS U-Pb定年, 获得大宁岩体形成年龄为441.1±3.0 Ma, 其包体年龄为439.5±3.6 Ma, 初洞岩体形成年龄为423.5~434.2 Ma。结果表明, 大宁岩体及其包体几乎同期形成, 而初洞岩体是后期的侵入体。Lu-Hf同位素研究结果表明, 大宁岩体及其暗色包体与初洞岩体具有相似的Hf同位素组成, 在εHf(t)-年龄图上落在1440~1960 Ma的老地壳区间, 表明三者的岩浆源区均是早元古代到中元古代地壳, 暗色包体是岩浆早期分离结晶的产物, 而初洞岩体是岩浆结晶分异晚期的产物。

关键词: 锆石U-Pb年代学, Hf同位素, 大宁岩体, 初洞岩体

Abstract:

LA-ICP-MS zircon U-Pb dating for Daning pluton, dark inclusions and Chudong pluton yield the weighted mean 206Pb/238Pb ages of 441.1±3.0 Ma, 439.5±3.6 Ma and 423.5-434.2 Ma, respectively, revealing that Daning pluton and the dark inclusions were formed almost concurrently, while the Daning pluton was intruded by the Chudong pluton. In-situ zircon Lu-Hf isotopic analyses of Daning pluton, dark inclusions and Chudong pluton show same characteristics with negative εHf(t) values, plotted within the revolution areas of the 1440-1960 Ma old continental crust in the age vs. εHf(t) diagrams. The Hf isotopic characteristics indicate that the magmas could be derived from the partial melting of Early Proterozoic to Mesoproterozoic crust materials. The dark inclusions were produced by the fractional crystallization of parental magma. The Chudong pluton was the advanced stage product of the magma crystallization differentiation.

Key words: zircon U-Pb dating, Hf isotopes, Daning pluton, Chudong pluton

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