湘西新元古界板溪群马底驿组下段地层含金性特征

Gold-bearing characterisics of the Neoproterozoic strata of lower end of Madiyi formation,Banxi group in Western Hunan Province

元古代板溪群是一套沉积韵律发育的浅海砂泥质碎屑岩及凝灰质碎屑岩,为湘西一带大量含金石英脉型金矿床、矿点和矿化点的赋矿地层。对马底驿组下段进行岩石学和地层含金性研究表明,马底驿组下段岩石类型主要为变质砂岩类和板岩类,两类岩石的金含量均分布均一,矿化程度低,受后期地质作用改造程度比较弱;同时,呈单偏峰分布的含金量频率分布型式和呈正态分布的对数频率分布型式表明该地层未遭受后期变质作用叠加,金的背景值总体偏低且趋于均一化,因此,认为产于板溪群中的金矿体成矿物质与马底驿组下段关系不大。

Neoproterozoic Banxi group is a set of neritic sand argillaceous clastic and tuffaceous clastic rocks with sedimentary rhythm development. This group is an ore formation which contains a large number of gold quartz vein type gold deposits,mineral occurrences and mineralization points in western Hunan Province. Lithology and gold-bearing potentiality research on lower end of Madiyi formation shows that rock types of the section are mainly metamorphic sandstones and slates,of which the gold content of distribute homogeneously,the degree of mineralization is low and the later geologic process transformation is poor. Moreover,the positive single peak distribution frequency pattern and normally distributed logarithmic frequency pattern show that the formation has not suffered late metamorphism,the overall gold background value is low and tends to be homogeneous. Consequently,the ore-forming material sources generated in Banxi group gold deposit have little connection with the rock of lower end of Madiyi formation