黔西南泥堡金矿床'砾屑砂岩'的火山岩属性及其与金成矿的密切关系

摘要

"Rudaceous sandstone" is the most important host rock of gold ore body in Nibao gold deposit,it is possessed of typical microscopic textures and element geochemic composition of volcanic rock with hyalopilitic(andesitic) texture,contains 30.40%~32.90% of SiO2,and high content of CaO、MgO.Getting rid of the composition of altered sulfides and aqueous mineral,the original SiO2 content is about 55%~60%,belongs to basaltic andesite.This volcanic rock(so-called rudaceous sandstone) suffered from strong dolomite,clay alteration and gold mineralization,its gold content is higher than other gold host rock,so we consider Nibao gold deposit is related to late Permian volcanic vapour-hydrothermal metallogeny.%"砾屑砂岩"作为泥堡金矿床最主要的容矿岩石,经研究发现具有特殊的微观组构与地球化学元素组份特征,显微镜下表现为典型的交织结构(安山结构),主要化学成分SiO2含量30.40%32.90%,CaO、MgO含量较高,如果把后期蚀变含水矿物与硫化物的化学成份含量剔除,恢复原岩中SiO2含量(55%60%)为玄武安山质成份,属于中基性火山岩.这种玄武安山岩(原定砾屑砂岩)经历了强烈热液蚀变(白云石化、粘土化)和金矿化,其含金量比矿区其它容矿岩石都高,从而认为泥堡金矿床成矿作用与晚二叠世火山或火山气液作用相关.