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Geoscience ›› 2018, Vol. 32 ›› Issue (01): 45-55.DOI: 10.19657/j.geoscience.1000-8527.2018.01.04

• Petrology • Previous Articles     Next Articles

Geochemistry, Zircon U-Pb Geochronology and Hf-Sr-Nd Isotopic Characteristics of the Rhyolite Porphyry at Heyuanbei in Xiangshan Uranium Ore-field, Jiangxi Province

SI Zhifa1,2(), LI Ziying1,2, NIE Jiangtao1,2(), LIU Jungang1,2, WANG Jian1,2, TIAN Mingming1,2   

  1. 1. Beijing Research Institute of Uranium Geology, CNNC, Beijing 100029,China
    2. Key Laboratory of Uranium Resource Exploration and Evaluation Technology, CNNC, Beijing 100029,China
  • Received:2017-05-24 Revised:2017-09-20 Online:2018-02-10 Published:2018-02-05

Abstract:

A suite of rhyolite porphyry was found at Heyuanbei in Xiangshan uranium ore-field of Jiangxi Province, which intruded into the rhyodacite, tuff, argillaceous siltstone. LA-ICP-MS U-Pb isotopic dating on zircons from the rhyolite porphyry yields magmatic crystallization age of (131.8±0.7) Ma (MSWD=0.41). The rhyolite porphyry is characterized by high in SiO2, K2O, Al2O3 and relatively low in MnO and P2O5. It is enriched in Rb, Th, U, La, Ce, Nd and light rare earth elements, depleted in Ba, Nb, Sr, P and Ti, and shown slightly negative Eu anomalies (δEu=0.21-0.25). The zircon εHf(t) values range from -6.77 to -10.38, with Hf depleted mantle model ages (TDMC) between 1 619 and 1 846 Ma. The ISr values range from 0.710 92 to 0.712 01. And the εNd(t) values range from -8.18 to -9.19. The experimental results indicate that the rock was generated by partial melting of crustal rocks during extension in Lower Cretaceous. And a sub-volcanic conduit may exist in the west of Xiangshan.

Key words: rhyolite porphyry, geochemistry, zircon U-Pb dating, Hf-Sr-Nd isotope, Xiangshan uranium ore-field

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