Genetic mechanism of siliceous minerals in Permian marine shales in Northeast Sichuan
The content and genesis of siliceous minerals in marine shales are often closely related to the abundance and transformability of organic matter.To elucidate the occurrence characteristics and sources of siliceous minerals in the Permian marine shales of the study area,this paper carried out a systematic petrological and elemental geochemical analysis on field outcrop samples and drilling samples.The occurrence characteristics and origin of quartz in the shales of Wujiaping-Dalong Formation were deeply dissected by means of thin section of rock,scanning electron microscopy,energy spectrum analysis,principal and trace elements.The conclusions are as follows:①There are four main types of siliceous minerals:clastic quartz,quartz cement,siliceous bioclasts,and quartz veins;the origins of these siliceous minerals can be classified into three categories:volcanic eruption and terrigenous input,biological origin,and deep hydrothermal origin.②The siliceous shales are primarily deposited in the extensional trough graben areas;the content of Al,Ti and Th in the Wu 3 member is lower than that of the upper crust,and the detrital quartz of Wu 1 member,Wu 2 member and Dalong Formation is of terrigenous input origin;the Al-Fe-Mn and Zn-Ni-Co triangle diagrams show that the shale samples of the Wujiaping-Dalong Formation fall in the biogenic and hydrothermal origin areas,indicating that the quartz cements and quartz veins are mainly biogenic and hydrothermal;the development of siliceous minerals has a strong correlation with aqueous nutrient enrichment and organic matter accumulation.
万方数据
维普
