安徽铜陵志留系-三叠系沉积地层岩石学和地球化学：对层控夕卡岩矿床成因的约束  

Petrology and geochemistry of Silurian-Triassic sedimentary rocks in the Tongling area:Constraints on the genesis of stratabound skarn deposits

作　　者：杜轶伦[1,2,3] 曹毅[2,3] 霍东亮[4] 李大鹏[2,3] 高志伟[2,3] 

机构地区：[1]中国地质调查局发展研究中心,北京100037 [2]地质过程与矿产资源国家重点实验室 [3]中国地质大学(北京)地球科学与资源学院,北京100083 [4]中国武装警察部队黄金第八支队,新疆乌鲁木齐830057

出　　处：《地学前缘》2014年第1期228-239,共12页Earth Science Frontiers

基　　金：国家自然科学基金项目(40672045);中国地质调查局项目(20089938);中央高校基本科研业务费专项(2011YYL125)

摘　　要：沉积地层与层控夕卡岩矿床间的成因联系至今尚未完全查明。在安徽铜陵地区广泛分布的志留系—三叠系沉积地层中发育有大量层控夕卡岩Cu(Au)矿床,这些矿床成为研究沉积地层与层控夕卡岩矿床之间的成因联系的典型案例。岩石学研究表明,铜陵地区泥盆系至三叠系地层中存在3种岩性突变界面:粉砂岩与白云岩相变组合、灰岩(或白云岩)与硅质岩相变组合和白云岩与灰岩相变组合。其中,前两种组合是区内层控夕卡岩矿床的主要赋存层位。地球化学研究表明,各组地层沉积岩中的成矿元素含量较低,自身难以富集形成具规模的矿体。但是,在局部地区石炭系白云岩中的Fe含量较高,具有形成矿胚层的潜力。综合分析表明,铜陵地区层控夕卡岩矿床主要受控于矿胚层、构造-岩性组合、有机质和蒸发岩-膏盐层,其中,构造-岩性组合是主要控制因素(必要条件),而矿胚层仅为部分矿床的形成起到预富集作用,蒸发岩-膏盐层仅为部分矿床的形成提供了部分硫源以及在成矿作用过程中发挥吸附和还原作用,有机质也仅在部分矿床成矿过程中发挥吸附和还原作用。这些有益的研究结果为进一步总结层控夕卡岩的形成机理提供了许多有价值的实际材料,为今后的进一步研究提供了重要线索。Stratabound skarn deposits are widespread across the globe. These deposits are exploited for a wide variety of economic commodities, and the skarns, intrusives, altered rocks, and ores within skarn deposit have been the focus of a significant amount of researches. However, there is currently no model for the role of marine sedimentary rocks in contact metasomatism and mineralization associated with skarn formation. Paleozoic to Mesozoic marine clastic and carbonate sediments are widespread throughout the Tongling area of Anhui province, East China, and are associated with a number of skarn deposits, making this area an excellent natural laboratory for studying interactions between marine sediments and skarn mineralization. Here, we present the results of the petrology and geochemistry of Silurian to Triassic sedimentary rocks in this area, focusing at the distribution of different types of skarn deposit within different sedimentary units. Petrology shows that there are three types of abrupt lithologic change in sedimentary rocks of Silurian to Triassic age in Tongling area： dolomite-siltstone, dolomite-siliceous sediments, and dolomite-limestone. The first two suddenly changed associations are the main hosts for skarn orebodies in the study area. Geochemical analysis indicates that the Clarke concentration （i. e. , the concentration of an element in a rock compared with its average concentration in the earth＇s crust） of ore forming elements within sedimentary rocks in the Tongling area is much lower than the concentration coefficient （i. e. , the amount by which an element must be increased above its normal crustal abundance to make it commercially viable to mine）, meaning that the skarn mineral deposits in this area are unlikely to have formed without involvement of external material. However, the relatively high contents of Fe within Carboniferous dolomites in parts of the study area mean that these dolomites may represent potential sources for metals within the skarn deposits. We show that th

关 键 词：层控夕卡岩矿床 构造-岩性组合 矿胚层 有机质 蒸发岩-膏岩层 

分 类 号：P611[天文地球—矿床学]