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Geoscience ›› 2020, Vol. 34 ›› Issue (06): 1230-1244.DOI: 10.19657/j.geoscience.1000-8527.2020.043

• Petrology • Previous Articles     Next Articles

Petrogenesis and Tectonic Significance of the Wuzhangshan Pluton in Xiong’ershan, Western Henan Province: Constraint from Petrogeochemistry and Sr-Nd-Pb Isotopes

RAO Shicheng1(), WANG Changming1,2(), HE Xinyu3, SHI Kangxing1, ZHU Jiaxuan1, CHEN Qi1, DUAN Hongyu1, LI Pengwei1   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
    2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China
    3. China Non-ferrous Metals Resource Geological Survey, Beijing 100012, China
  • Received:2020-05-29 Revised:2020-06-23 Online:2020-12-22 Published:2020-12-22
  • Contact: WANG Changming

Abstract:

To analyze the magma origin and mechanism of the Yanshanian magmatism in eastern China, the authors conducted a study on the petrography, Sr-Nd-Hf isotope systematics, whole-rock major and trace element geochemistry of the Wuzhangshan pluton in Xiong’ershan. The Wuzhangshan pluton consists of biotite hornblende monzogranite, which is characterized by high SiO2(66.44%-71.71%) and alkali contents (Na2O+K2O=9.8%-10.06%). The rocks contain relative high Al2O3(14.52%-15.63%), and low TFeO (1.71%-3.47%), CaO (0.51%-2.56%) and MgO (0.19%-0.59%), indicating their shoshonitic and metaluminous nature. The samples are enriched in LREEs, K, Sr, Pb, Zr, and Hf, but depleted in high field strength elements (HFSEs) such as HREEs, Ta, Nb, P,and Ti. These rocks have no obvious Eu anomaly (δEu=1.00-1.13) and with I-type granite characteristics. They have (87Sr/86Sr)i=0.707,3 to 0.708,0, εNd(t)=-20.5 to -17.9, and T D M 2 =2,599 to 2,389 Ma. Lead isotope compositions are similar (206Pb/204Pb=17.305-17.754; 207Pb/204Pb = 15.427-15.481; 208Pb/204Pb = 37.766-37.999), indicating that rocks were sourced from ancient crust material. These rocks have high values of Sr/Y (40.85-236.72) and La/Yb (19.34-30.46), indicating adakite-like features. The low MgO, Cr, and Ni contents and low Mg# values indicate that the monzogranite was formed by partial melting of the thickened lower crust, probably related to the north-dipping intracontinental subduction of the Yangtze plate.

Key words: Wuzhangshan pluton, Sr-Nd-Pb isotope, geochemistry, petrogenesis, Xiong’ershan

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