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Geology,Distribution,Types and Tectonic Settings of Mesozoic Epithermal Gold Deposits in East China

MAO Jing-wen1 2, LI Xiao-feng2, ZHANG Zuo-heng2, WANG Yi-tian2, LI Hou-min1, HU Hua-bin1   

  1. 1. China University of Geosciences, Beijing 100083, China; 2. Institute of Mineral Resources, Chinese Academy of Geological Science, Beijing 100037, China
  • Received:2003-12-20 Revised:2003-12-20 Online:2003-12-20 Published:2003-12-20

Abstract: We preliminarily describe the basic characteristics of the epithermal gold deposits in East China.The epithermal gold deposits in East China can be divided into low-sulfidation and high-sulfidation types,which are related to granitic and alkaline series magmatic rocks.Except for the Zijinshan in Fujian province and the Tiantoushan in Anhui province,the others are low sulfidation epithermal gold deposits.The Guilaizhuang in the west Shandong and possibly the Yixingzhai in northwestern Shanxi are alkaline rock-related gold deposits.The epithermal gold deposits in East China are spatially distributed in the faulting-depressing volcanic basins or along the magmatic-volcanic zones in the uplift areas. Most of them are structurally continued by calderas ,craters,diatremes and related faults and hosted in volcanic rocks ,intrusions and surrounding strata.The alteration assemblages are mainly adularia-chalcedony-sericite for low-sulfidation gold deposits,and alunite-kaolinite-quartz(chalcedony)for high-sulfidation gold deposits.In genera1, the alterations in these Mesozoic gold deposits do not show the obvious zoning as those in the Cenozoic gold deposits in the southeast Pacific islands an d Japan.The ore-forming ages of the epithermal gold deposits in East China are within four pulses of 180—188 Ma,135—144 Ma,127—115 Ma an d 94—105 Ma.respectively.The former three pulses geodynamieally correspond to the extensional periods of post-collision orogenic process between North China and Yangtze cratons ,transformation of the tectonic regime from N to nearly EW —directions ,and significant thinning process of the lithosphere;The latter pulse is the products of the lithosphere extension in South China .We suggest that all the epithermal gold deposits in East China are the products of magmatic heat events in the extensional tectonic setting within the continental margin.