安徽铜陵冬瓜山铜(金)矿床成矿模式  

A metallogenic model for the Dongguashan Cu-Au deposit of Tongling,Anhui Province

作　　者：陆建军[1] 郭维民[1] 陈卫锋[1] 蒋少涌[1] 李娟[1] 颜晓蓉[1] 徐兆文[1] 

机构地区：[1]南京大学成矿作用国家重点实验室,南京大学地球科学与工程学院,南京210093

出　　处：《岩石学报》2008年第8期1857-1864,共8页Acta Petrologica Sinica

基　　金：国家自然科学基金(49873016);高等学校博士学科点专项科研基金(1999028435)资助项目

摘　　要：长江中、下游断裂坳陷带是我国重要的铜、金、铁、硫成矿带,存在一系列块状硫化物矿床及与其伴生的矽卡岩型和斑岩型矿床。本文以铜陵矿集区冬瓜山铜、金矿床为例,探讨了这类矿床的成矿模式。冬瓜山矿床主要由层状硫化物矿体组成,伴有矽卡岩型和斑岩型矿体。层状硫化物矿体产于晚泥盆世砂岩和晚石炭世碳酸盐岩之间,具明显的层控特征,矿体下盘发育细脉—网脉状硫化物矿化以及硅化和绢云母化,矿体中伴有热水沉积岩,矿石具典型的沉积构造。燕山期岩浆热液对层状矿体进行了叠加和改造,改变了矿石的结构构造和矿石成分。黄铜矿交代黄铁矿变斑晶呈环斑结构或脉状交代结构,交代磁黄铁矿呈交代假象结构或交代残留结构。矽卡岩型矿体中黄铜矿的δ^(65)Cu 值为0.09‰～0.83‰,集中在0.23‰～0.83‰。层状矿体中黄铜矿的δ^(65)Cu 值为0.45‰～0.78‰,与矽卡岩矿体中黄铜矿的^(65)Cu 值大致相当,这说明两类矿体中的铜具有相同的来源。铜、氢和氧同位素研究表明,冬瓜山矿床铜来自岩浆岩,叠加的成矿流体主要为岩浆流体。提出了冬瓜山矿床属喷流沉积—岩浆热液叠生成因的成矿模式:在晚石炭世,海底喷流成矿作用形成了块状硫化物矿床,矿石成分以硫、铁为主;燕山期岩浆热液一方面对块状硫化物矿床进行改造,致使其富集铜等成矿物质,另一方面与围岩相互作用形成矽卡岩型和斑岩型矿体。The Middle-Lower Reach of Yangtze River is an important metallogenic belt for copper, gold, iron and other elements where there are a number of massive sulfide deposits associated with skarn- and porphyry-type deposits. Taking the Dongguashan Cu-Au deposit of Tongling in Anhui Province as a study case, the paper discusses the metallogenic mechanism of these Cu-Au deposits. The Dongguashan deposit include stratiform sulfide orebodies, skarn- and porphyry-type orebodies. The stratiform ore bodies with obvious stratabound feature occurred between the Late Devonian sandstones and the Late Carboniferous carbonates, have typical sedimentary structures, such as microbedding and yielding structure, and are associated with synchronous hydrothermal sedimentary rocks. There are veinlet and stockwork sulfide mineralization, and silicifieation and sericitization below the stratiform ore bodies. These stratiform ore bodies are considered as massive sulfide deposit. The Late Jurassic magmatie activities hydrothermally superimposed the stratiform ore bodies and altered their textures, structures and compositions. Chalcopyrite replaced pyrite metacryst, which formed ring texture and veinlet replacement texture, and kept the shape of pyrrhotite after replacing it. The 865 Cu values of ehalcopyrite from the skarn ores vary from 0. 09‰ to 0. 83‰, with a concentrated range of 0. 23‰ -0. 83‰. Chalcopyrite from the stratiform ores has the δ65Cu values of 0. 45‰ - 0. 78‰, compatible with those of chalcopyrite from the skarn ores and from high temperature hydrothermal deposits, which indicates that the copper of both the strafiform orebodies and skarn ores has the same source and may come dominantly from magmatic rocks. The hydrogen and oxygen isotope compositions indicate the ore-forming fluids associated with copper mineralization were originated from magmatic fluids. A submarine exhalative sedimentary --magmatie hydrothermal diplogenetie model for the Dongguashan deposit is proposed. The model can be described as： durin

关 键 词：铜同位素 海底喷流沉积成矿作用 岩浆热液成矿作用 成矿模式 冬瓜山铜 金矿床 

分 类 号：P597.2[天文地球—地球化学] P618.41[天文地球—地质学]