地质学报2011，Vol.85Issue(7)：1223-1232,10.DOI:11-1951/P.20110715.0858.015
安徽铜陵冬瓜山铜矿床的叠加改造成矿机制:来自矿石结构的证据
The Superimposed Mineralization of the Dongguashan Cu Deposit in Tongling Area, Anhui Province: Evidence from the Ore Texture
摘要
Abstract
The massive sulfide deposits in the Middle-Lower region of Yangtze River have undergone extensive superimposition and reformation by Yanshanian magma. Taking the Dongguashan Cu deposit in Tongling as a study case, this paper discusses the metallogenic mechanism of these Cu deposits. Dongguashan deposit comprises mainly of a large stratiform sulfide orebody with some subordinate skarn and porphyry type orebodies. Field and microscopic investigation show that the sulfide ores at Dongguashan deposit underwent intensive thermal metamorphism and hydrothermal replacement. The prograde ore textures were formed through the phase conversions from pyrite to pyrrhotite and magnetite by the heating of Yanshanian granite magma. Retrograde metamorphism is characterized by presence of annealing textures in pyrrhotite, porphyroblastic growth of pyrite and formation of pure hexagonal pyrrhotite. The hydrothermal replacement textures were represented by the intergrowths of hexagonal and monoclinic pyrrhotites and replacement of pyrrhotites and pyrite by chalcopyrite. The chalcopyrite in the stratiform orebody was formed by replacement of pyrite and pyrrhotite, which have experienced contact metamorphism related to the Yanshanian intrusions. This suggests that chalcopyrite in the stratiform orebody was mainly overprinted from the Yanshanian magmatic fluids. The pre-existing pyrrhotite and pyrite have important significance for the precipitation of chalcopyrite from magmatic fluids. Base on the characteristics of ore textures, the formation of Dongguashan Cu deposit can be described as three stages: 1) During the Carboniferous period, the massive sulfide deposit was formed by the submarine exhalative and sedimentation, the compositions of which were dominantly S and Fe; 2) The heat from Yanshanian granite intrusions has resulted in phase changes from the pyrite to pyrrhotites and magnetite, and then the stratiform sulfide orebody has underwent a slow cooling process; 3) The overprinting of magmatic hydrothermal fluids lead to enrichment of large amounts of copper in the stratiform orebody, and formed new skarn and porphyry type orebodies.关键词
矿石结构/冬瓜山铜矿床/叠加改造/铜陵Key words
Ore texture/ Dongguashan copper deposit/ superimposition-reformation/ Tongling引用本文复制引用
郭维民,陆建军,章荣清,招湛杰,徐兆文..安徽铜陵冬瓜山铜矿床的叠加改造成矿机制:来自矿石结构的证据[J].地质学报,2011,85(7):1223-1232,10.基金项目
本文为高等学校博士科学点专项科研基金(编号1999028435)资助的成果. （编号1999028435）
