贵州二叠纪龙潭期硫铁矿沉积环境及成矿模式

Sedimentary environment and mineralization pattern of pyrite deposits at Longtan stage of Permian in Guizhou

贵州二叠纪龙潭期硫铁矿床主要为沉积型矿床,赋存层位主要为二叠系龙潭组、合山组(同时异相沉积)底部,为贵州省主要的硫铁矿资源。对贵州省域范围内二叠纪龙潭期硫铁矿含矿系和矿体特征的分析表明,龙潭组含矿系主要为高岭石化黏土岩、含炭质泥岩,合山组主要为高岭石黏土质页岩。分析认为二叠纪峨眉山玄武岩喷发带来铁质物源,动植物有机质分解形成硫质物源,在二叠纪龙潭早期缓慢海侵过程中,海水自贵州南部向北西侵入,在潮坪—潟湖沉积沼泥中的还原环境下形成黄铁矿,在成岩—后生作用阶段重结晶而形成硫铁矿床。基于贵州二叠纪龙潭期硫铁矿厚度、品位分布规律及其沉积环境的研究,分析了硫铁矿的成矿模式,认为硫铁矿主要发育于沼泽、潮坪及潟湖滞流环境,且于二叠纪龙潭早期的首次海侵过程中形成。

There are mainly sedimentary pyrite deposits at Longtan stage of Permian Era in Guizhou,and the hosted mineralization layer is mainly at the bottom of Longtan Formation and Heshan Formation(simultaneous and heterogeneous sediment)of the Upper Permian.The deposits are the main pyrite resources in Guizhou Province.The analysis of the upper Permian pyrite-bearing rocks and orebodies in Guizhou shows that the Longtan Formation is mainly kaolinitic claystone and carbonaceous mudstone,while the Heshan Formation is mainly kaolinitic claystone shale.It is believed that in Permian Era the Emeishan basalt eruption brings the material source of iron,and the decomposition of plant and animal organic materials is the source of sulfur.During the slow transgression process in the early Longtan stage of Permian,seawater invaded toward the northwest from south Guizhou,in the Chaoping-lagoon sedimentary mud pyrite formed in the reduction environment,and pyrite recrystallized in the diagenesis-epigenesis stage to form the sulfide deposit.Based on the study of the thickness and grade distribution of pyrite layer in Longtan stage of Permian and its sedimentary environment,the metallogenic model of pyrite deposit is analyzed.It is proposed that pyrite mainly formed in the stagnant environments of swamp,tidal flat and lagoon stagnation during the first transgression in the early Longtan stage of Permian.