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W-Sn-Nb-Ta-Bearing Granites in the Nanling Range and Their Relationship to Metallogengesis

CHEN Jun, LU Jian-Jun, CHEN Wei-Feng, WANG Ru-Cheng, MA Dong-Sheng,ZHU Jin-chu, ZHANG Wen-lan and JI Jun-Feng   

  1. School of Earth Sciences and Engineering, State Key Laboratory of Mineral Deposits Research,Nanjing University, Nanjing 210093, China
  • Received:2008-12-20 Revised:2008-12-20 Online:2008-12-20 Published:2008-12-20

Abstract: The large-scale mineralizations of W, Sn, Nb and Ta related to granites took place in the Late Jurassic period in Nanling Range, South China. According to the petrological and geochemical features of ore-bearing granites and their relationship to mineralizations, they can be grouped into the following three major types: W-bearing granites, Sn-W-bearing granites and Ta-Nb-bearing granites. The W-bearing granites show low TiO2 and Ba+Sr contents and LREE/HREE ratios,intensive Eu depletion, high Rb and Y abundances and Rb/Sr ratios, and oversaturation in Al. They commonly underwent intensive differentiation and evolution. The Sn-W-bearing granites are characterized by enrichment of TiO2, total REE, HFSEs,Ba+Sr and Rb, higher CaO/(K2O+Na2O) and LREE/HREE ratios, metaluminous-weakly peraluminous feature and lower Rb/Sr ratios, and weaker differentiation and evolation. The Ta-Nb-bearing granites have very low TiO2, Ba+Sr, total REE and HFSEs contents and CaO/(K2O+Na2O) ratios, higher Al2O3/TiO2 and Rb/Sr ratios, higher Rb and Nb contents, and ACNK values. They are highly evolved. Good discrimination can be obtained between these three types of W-Sn-Nb-Ta-bearing granites on plots employing Nb-Y-Ce, (Ba+Sr)-Rb-(Zr+Nb+Ce+Y), LREE/HREE-Rb/Sr and LREE/HREE-(Zr+Nb+Ce+Y) diagrams. These three types of ore-bearing granites have obviously different evolutional trends. Metallogenesis is intimately related to the evolution of the ore-bearing granites. Mineralizations of Sn, W or W-Sn and Nb-Ta or Sn-W-Nb-Ta are closely related to biotite granites, twomica granites or muscovite granites and albite granites respectively. The important deposit types of W, Sn, Nb and Ta and their major features in the Nanling Range are summarized in the paper. The chloritized granite type tin deposit is proposed. This paper indicates that an attention to searching for both the chloritzed granite type tin deposits and greisen-quartz vein type W-Sn deposits in W-Sn-bearing granites in the Nanling Range should be especially paid.