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Geoscience ›› 2020, Vol. 34 ›› Issue (06): 1277-1290.DOI: 10.19657/j.geoscience.1000-8527.2020.046

• Petrology • Previous Articles     Next Articles

Geochronology, Petrogenesis and Geological Significance of the Puquan Granite Pluton in Dayaoshan Area, Guangxi

CHEN Huan1,2(), KANG Zhiqiang1,2(), WU Jiachang3, LI Daixian1,2, CAO Yan1,2, WEI Tianwei1,2, WEI Naishao1,2, LIU Di1,2, ZHOU Tong1,2, LIU Dongmei1,2, LAN Haiyang4   

  1. 1. School of Earth Science, Guilin University of Technology, Guilin, Guangxi 541004, China
    2. Collaborative Innovation Center for Exploration of Hidden Nonferrous Metal Deposits and Development of New Materials in Guangxi, Guilin, Guangxi 541004, China
    3. Guangxi Geological Exploration Institute of China Metallurgical Geology Bureau, Nanning, Guangxi 530000, China
    4. Liaoning Metallurgical Geological Exploration Research Institute Co.Ltd., Anshan, Liaoning 114038, China
  • Received:2019-06-05 Revised:2020-07-02 Online:2020-12-22 Published:2020-12-22
  • Contact: KANG Zhiqiang

Abstract:

Caledonian magmatic rocks are widespread in the Dayaoshan uplift zone in Guangxi Province, and research on them has instructional significance for understanding the geodynamic setting, evolution mechanism and prospecting work of Dayaoshan uplift. This paper present the first detailed geochronological, elemental and Hf isotope study on the Puquan intrusion in the northwestern uplift zone. LA-ICP-MS zircon U-Pb dating on the Puquan intrusion yielded Late Ordovician age of (441.1±1.2) Ma (MSWD=0.14). The intrusion comprises medium-fine-grained I-type granite, and is characterized by high SiO2 (68.50%-72.83%) and medium Al2O3 (13.66%-14.42%) contents and medium alkalinity (total alkali=7.17%-8.34%, K2O/Na2O=0.75-1.33) with A/CNK=0.89-1.18, suggesting its metaluminous to weakly peraluminous nature. The rocks are enriched in LILEs (such as Rb, Th, U, and Pb) and depleted in Ba, Sr, Nb, and Ti. The total REE contents are 97.41×10-6-178.80×10-6, and the rocks have distinctly negative Eu anomalies (δEu=0.12-0.14). The magmatic zircon εHf(t) values are mostly negative (-14.92 to 2.75), with an average of -2.67. In the εHf(t) vs. age and the (176Lu/177Hf) vs. age diagrams, the samples fall below the chondrite evolution line, and the two-stage model ages ( t D M 2 ) are of 1.2 Ga to 2.4 Ga (average 1.6 Ga), indicating that the rocks may have derived from partial melting of the Mesoproterozoic crustal material with possible mantle-derived components. This shows that the Puquan intrusion was formed under syn-collisional compression between the Yangtze and Cathaysia Plate.

Key words: Puquan granitic pluton, LA-ICP-MS zircon U-Pb dating, Hf isotope, Caledonian, Dayaoshan (Guangxi)

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