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Ore-Forming Material Sources for Xiangshan Uranium 0re-Field in Jiangxi Province: Evidence from Nd-Sr-Pb Isotopes

FAN Hong-hai, LING Hong-fei, WANG De-zi, SHEN Wei-zhou,LIU Chang-shi, JIANG Yao-hui   

  1. Department of Earth Sciences and State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China
  • Received:2001-06-20 Revised:2001-06-20 Online:2001-06-20 Published:2001-06-20

Abstract: The Xiangshan volcanic rock related uranium ore-field is the 1argest uranium ore-field in China The Zoujiashan uranium deposit(fluorite-hyromica-uraninite association)and the Shazhou uranium deposit ( alkali feldspar alteration-hemitite-uraninite association) are the two representatives of the ore-field This paper presents Nd,Sr and Pb isotope compositions of these two uranium deposits and their wall rocks-the Xiangshan volcanic rocks εNd(t)values(-6.7~ -8.3)and initial 87Sr/86Sr ratios(0.7145~0.7207)of fluorite formed by the ore-forming hydrothermal fluid are similar to those of the wall rocks(εNd(t)=-6.2~-9.4,initial 87Sr/86Sr Sr=0.7121~O.7192). In the εNd(t) vs .t diagram,the plot area of data points for fluorite of ore-forming stage is generally identical with that of the host rocks. Both of them fall within the evolution domain of Proterosoic basement in Xiangshan area Pyrites from the ores have a linear correlation between 206Pb/204Pb and 207Pb/204Pb, while the wall rocks plot at the 1owe/value end of this corelation 1ine. From this 1ine a reference age of 144 Ma can be obtained, which is consistent with the age of the volcanic rocks(135~ 140Ma) This Nd-Sr-Pb isotope evidence suggests that the ore forming materials were derived mainly from the Xiangshan volcanic rocks The volcanic rocks were derived mainly from the crust which was similar to the exposed basement. Therefore,the main ore-forming materials were derived ultimately from the crust