Petrogenesis of Low Sr and High Yb A-Type Granitoids in the Xianghualing Sn Polymetallic Deposit, South China: Constrains from Geochronology and Sr–Nd–Pb–Hf Isotopes
| Autor: | ChangShan Wei, YuKe Shen, ChangHao Xiao |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
lcsh:Mineralogy
lcsh:QE351-399.2 010504 meteorology & atmospheric sciences Sr–Nd–Pb–Hf isotopes Geochemistry Partial melting Geology 010502 geochemistry & geophysics Geotechnical Engineering and Engineering Geology 01 natural sciences Tectonics low Sr and high Yb A2-type granite zircon U–Pb geochronology Asthenosphere Geochronology Magmatism Xianghualing Lithophile South China 0105 earth and related environmental sciences Zircon Petrogenesis |
| Zdroj: | Minerals, Vol 9, Iss 3, p 182 (2019) Minerals Volume 9 Issue 3 |
| Popis: | The nature and origin of the early Yanshanian granitoids, widespread in the South China Block, shed light on their geodynamic setting however, understanding their magmatism processes remains a challenge. In this paper, we present both major and trace elements of bulk rock, Sr&ndash Nd&ndash Pb isotopic geochemistry, and zircon U&ndash Pb&ndash Hf isotopes of the low Sr and high Yb A2-type granites, which were investigated with the aim to further constrain their petrogenesis and tectonic implications. Zircon U&ndash Pb dating indicates that these granites were emplaced at ca. 153 Ma. The granites are characterized by high SiO2 (> 74 wt.%) and low Al2O3 content (11.0 wt.%&ndash 12.7 wt.% < 13.9 wt.%). They are enriched in large ion lithophile elements (LILEs) (e.g., Rb, Th, U, and K) and Yb, but depleted in high field-strength elements (HFSEs) (e.g., Nb, Ta, Zr and Hf), Sr, Ba P, Ti and Eu concentrations. They exhibit enriched rare earth elements (REEs) with pronounced negative Eu anomalies. They have &epsilon Nd(t) values in a range from &minus 6.5 to &minus 9.3, and a corresponding TDM model age of 1.5 to 1.7 Ga. They have a (206Pb/204Pb)t value ranging from 18.523 to 18.654, a (207Pb/204Pb)t value varying from 15.762 to 15.797, and a (208Pb/204Pb)t value ranging from 39.101 to 39.272. The yield &epsilon Hf(t) ranges from &minus 6.1 to &minus 2.1, with crustal model ages (TDMC) of 1.3 to 1.6 Ga. These features indicate that the low Sr and high Yb weakly peraluminous A2-type granites were generated by overlying partial melting caused by the upwelling of the asthenosphere in an extensional tectonic setting. The rollback of the Paleo-Pacific Plate is the most plausible combined mechanism for the petrogenesis of A2-type granites, which contributed to the Sn&ndash W polymetallic mineralization along the Shi-Hang zone in South China. |
| Databáze: | OpenAIRE |
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