河南桐柏破山银矿床原生地球化学异常模式

Model of Primary Geochemical Anomalies of The Poshan Silver Deposit in Tongbai County,Henan Province

破山银矿是典型的变质碎屑岩型层控特大型银矿床,位于南阳、吴城断陷盆地之间,它经历了长期、复杂的地质发展历史,其成生、演化具多阶段性。成矿作用是在沉积、成岩、变质的基础上,经后期热液作用叠加,主要成矿作用为加里东晚期地下热水溶滤富集。成矿物质来自上元古界歪头山组上、中部,主要成矿元素具有明显的分带现象——上部富银、下部富锌。矿体周围紧密伴有Ag、Pb、Zn、Cd、As、Cu、Mn、(Sb)等元素组合异常。在对矿床原生地球化学异常特征总结的基础上,建立原生地球化学异常模式和找矿评价的地球化学标志。

The Poshan silver deposit is a typical extra-large stratabound deposit of metamorphosed clastic rock type. Located between the Nanyang and Wucheng basins, it experienced a long and complex geological history and multi-phased formation and evolution. On the basis of sedimentation, diagenesis and metamorphism, its ore-forming processes were suffered superposition of succeeding hydrothermal process and the main mineralization was Caledonian geothermal water leaching and enrichment. The ore-forming material came from the upper and middle Waitoushan formation of the Neoproterozoic. The distribution of the major ore-forming elements display obvious zoning phenomenon--silver enrichment in the upper portion, while zinc in the lower. The element assemblage anomalies of Ag, Pb, Zn, Cd, As, Cu, Mn, and （Sb） are associated with the deposit in the surrounding areas. Based on the summarization of the primary geochemical anomal characteristics of the deposit, the authors have established a model for the primary geochemical anomalies and geochemical criteria for ore prospecting.