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高校地质学报 ›› 2023, Vol. 29 ›› Issue (3): 455-470.DOI: 10.16108/j.issn1006-7493.2021077

• 其他学科 • 上一篇    下一篇

广西姑婆山花岗岩早白垩世暗色包体的识别及其地质意义

刘风雷1, 2，周 云1*，史水平4，冯佐海1, 3，蔡永丰1, 3，付 伟1, 3，赵 锴1   

  1. 1. 桂林理工大学 广西隐伏金属矿产勘查重点实验室，桂林 541004；
    2. 浙江有色地勘集团有限公司，绍兴 312000；
    3. 桂林理工大学 有色金属矿产勘查与资源高效利用省部共建协同创新中心，桂林 541004；
    4. 广西壮族自治区地震局，南宁 530022
  • 出版日期:2023-06-20 发布日期:2023-06-20

Identification of Early Cretaceous Dioritic Enclave of Guposhan Granite in Guangxi and Its Geological Significances

LIU Fenglei1, 2，ZHOU Yun1*，SHI Shuiping4，FENG Zuohai1, 3，CAI Yongfeng1, 3，FU Wei1, 3，ZHAO Kai1   

  1. 1. Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin University of Technology, Guilin 541004, China；
    2. Zhejiang Nonferrous Geological Exploration Group Co., Ltd, Shaoxing 321000, China；
    3. Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources in Guangxi, Guilin University of Technology, Guilin 541004, China；
    4. Earthquake Agency of Guangxi Zhuang Autonomous Region, Nanning 530022, China
  • Online:2023-06-20 Published:2023-06-20

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摘要： 为了探讨桂东北中生代构造演化特征，文章对桂东北姑婆山复式花岗岩体及其闪长质暗色包体进行了详细的岩石学、年代学和地球化学研究。年代学测试结果表明，闪长质暗色包体的形成时代为142±1 Ma，为首次在本区识别出了早白垩世闪长质暗色包体。元素地球化学分析结果显示闪长质暗色包体的SiO2含量为55.66%~56.72%，MgO为2.26%~2.30%，Fe2O3T为10.43%~10.77%；寄主花岗岩样品的SiO2含量为68.33%~68.67%，Fe2O3T为3.73%~3.89%，MgO为0.60%~0.64%，具有较高的10000Ga/Al比值和Zr+Nb+Ce+Y含量，整体表现出A型花岗岩的地球化学特征。寄主岩石和暗色包体均富含大离子亲石元素和高场强元素。综合上述数据，表明闪长质暗色包体是岩浆混合作用的产物，其形成与华南晚中生代岩石圈的伸展减薄作用有关；结合相关区域地质资料，表明华南中生代时期的岩石圈伸展减薄呈幕式发生，从而导致华南发育多期次、多阶段的岩浆作用。

关键词: 暗色包体, 姑婆山, 花岗岩, 锆石U-Pb年龄, 岩石圈伸展减薄

Abstract: In order to figure out the Mesozoic tectonic evolution of the northeastern Guangxi, this paper presented detailed petrological, chronological and geochemical data on the Guposhan composite rock mass and its dioritic enclaves. The chronological results show that the formation age of the dioritic enclaves is 142±1 Ma, for the first time to identify Early Cretaceous dioritic enclaves in this area. Elemental geochemical analysis results show that the contents of SiO2, MgO and Fe2O3T of the dioritic enclaves are 55.66%-56.72%, 2.26%-2.30% and 10.43%-10.77%, respectively; the contents of SiO2, MgO and Fe2O3T of the host granite sample are 68.33%-68.67%, 0.60%-0.64% and 3.73%-3.89%, respectively. The granites are characterized by high 10000*Ga/Al ratios and Zr+Nb+Ce+Y contents, similar with those of A-type granite. Both the host rock and the dioritic enclave are enriched in large ion lithophile elements and high field strength elements. The above data indicate that the dioritic enclaves are produced by magmatic mixing, and their formation is related to extension and thinning of the lithosphere in the Late Mesozoic. Together with regional geological data, it is suggested that the Mesozoic extension of the lithosphere in South China was episodic, which led to the development of multi-stage magmatism in South China.

Key words: dark enclave, Guposhan, granite, zircon U-Pb age, lithospheric extension and thinning

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