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A Two-Stage Model for Formation of the Dongguashan Cu-Au Deposit

LU Jian-jun, HUA Ren-min, XU Zhao-wen, GAO Jian-feng, LI Juan   

  1. State Key Lab. For Mineral Deposits Research, Nanjing University, Nanjing 210093, China
  • Received:2003-12-20 Revised:2003-12-20 Online:2003-12-20 Published:2003-12-20

Abstract: The Dongguashan Cu-Au deposit includes stratiform sulphide orebodies,and skarn and porphyry type orebodies.The stratiform orebodies occur between the Late Devonian sandstones and the Middle to Late Carboniferous carbonates.Detailed field and laboratory investigations revealed that these stratabound orebodies are massive sulphide deposit.The Late Juarassic magmatic rocks were brought to be in contact with the masive sulphide orebodies and caused them to be transformed and hydrothermally superimposed.The copper-bearing magmatic fluids replaced massive sulphides ores and formed chalcopyrite in them .A two-stage model for the formation of the Dongguashan deposit can be established .In the first ore-forming stage during the Middle Carboniferous period ,submarine exhalation sedimentation caused the formation of massive sulphide orebodies which contain dominantly pyrite,pyrrhotite,and some gangue minerals,but little copper-bearing sulphides.In the second stage at the Late Jurassic,magmatic hydrothermal fluids,on the one hand,formed the skarn and porphyry type of ore bodies ,on the other hand,overprinted the earlier massive sulphide orebodies ,and induced enrichment of large amounts of copper in the stratiform sulphide ores .