Metallogenetic Mechanism and Timing of Late Superimposing Fluid Mineralization in the Dongguashan Diplogenetic Stratifie
An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of the Yangtze Block during 140-135 Ma under extensional tectonic circumstances following the collision between the North China and Yangtze blocks. The main orebodies of the Dongguashan copper deposit, a typical diplogenetic stratified deposit among many polymetallic ore deposits in China, are hosted by strata between Upper Devonian sandstone and Carboniferous limestone, and its mineralization was genetically related to the Qingshanjiao intrusive. The Rb-Sr isotopic isochron of the Qingshanjiao intrusive yields an age of about 136.5±1.4 Ma. The ore-forming fluid reflected by the inclusion fluid in quartz veins is characterized by high temperature and high salinity, and its age was also determined by Rb-Sr isotope dating as 134±11 Ma. Oxygen and hydrogen isotope composition data suggest that the ore-forming fluid was derived mainly from magmatism. By integrating these isotopic dating data, characteristics of fluid inclusions and the geology of the deposit, the mineralization of the Dongguashan copper deposit is divided into two stages. First, a stratiform sedimentary deposit or protore layer formed in the Late Devonian to the Early Carboniferous, while in the second stage the pre-existing protore was superimposed by hydrothermal fluid that was derived from the Yanshanian magmatic activities occurring around 135 Ma ago. This two-stage mineralization formed the Dongguashan statiform copper deposit.Associated "porphyry" mineralization found in the bottom of and in surrounding intrusive rocks of the orebodies might have occurred in the same period as a second-stage mineralization of this deposit.
作 者： XU Zhaowen LU Xiancai LING Hongfei Lu Jianjun JIANG Shoyong NIE Guiping HUANG Shunsheng Hua Ming 作者单位： XU Zhaowen,LU Xiancai,LING Hongfei,Lu Jianjun,JIANG Shoyong(State Key Laboratory of Mineral Deposit Research,Department of Earth Sciences,Nanjing University,Hankou Road 22,Nanjing,Jiangsu 210093)NIE Guiping,HUANG Shunsheng,Hua Ming(Geological Survey of Jiangsu Province,Nanjing,Jiangsu 210018)
刊 名： 地质学报（英文版） SCI 英文刊名： ACTA GEOLOGICA SINICA 年，卷(期)： 2005 79(3) 分类号： P5 关键词： stratified copper deposit hydrothermal diplogenetic mineralization fluid inclusion metallogenetic epoch