The genetic type and its geological indication significance of shale minerals in Niutitang Formation

With the field emission scanning electron microscopy(SEM), the mineral components of shales in the Lower Palaeozoic Niutitang Formation(including the equivalent stratum)were observed at the micron scale-nanoscale. By revealing the characteristics of the growth and development of minerals and organic matter, the intuitive basis for judging the origin of minerals is obtained. The results show that the genetic types of shale minerals in Niutitang Formation are terrigenous detrital, authigenic(including alteration and biogenic, etc.), epigenetic, hydrothermal, supergene, and so on, and detrital and authigenic account for the main part. Different genetic minerals have different geological indication significance and have different effects on shale reservoir property. The intergrowth between biogenic quartz(including silica)and organic matter indicates the favorable layer of shale gas exploration.