陆相富有机质页岩黄铁矿特征及意义 ———以鄂尔多斯盆地延长组和松辽盆地青山口组为例.

Pyrite is a widely developed mineral in organic-rich shale, which is of great significance to the identification of the depositional environment and hydrocarbon enrichment of organic-rich shale. By means of thin section identification, XRD (X-ray diffraction), argon-ion polishing, SEM, rock pyrolysis and gas sorption, the pyrite and its impacts of reservoirs in organic-rich shale in the Yanchang Formation of Ordos Basin and Qingshankou Formation of Songliao were analyzed. The results show these as follows. The content of pyrite and the particle size of pyrite framboid in the Ordos Basin are larger than those in the Songliao Basin, the average particle size of pyrite framboid in each group of samples in Yanchang group is 13. 79 ~ 18. 1 μm, and most are 10 ~ 22 μm. The average particle size of pyrite framboid in each group of Qingshankou Formation is 2. 83 ~ 14. 92 μm, and most are 2 ~ 8 μm. The pyrite content in the Ordos Basin and Songliao Basin is proportional to the value of TOC (total organic carbon) and S1 + S2 . The average pore diameter of the two basins is proportional to the content of pyrite and inversely proportional to the particle size of pyrite framboid. The pyrite framboid in the organic-rich shale of the Yanchang Formation in the Ordos Basin is in early sedimentary-burial diagenetic stage with a shallow water oxidation environment. In organic-rich shale of the Qingshankou Formation in the Songliao Basin, there are two types of pyrites framboid: post-diagenetic deep-buried pyrites and early shallow-buried pyrites. The depositional environment of pyrite is semideep water sulfide environment and shallow water sub-oxidation-oxidation environment. Pyrite can promote the enrichment of organic matter and the development of porosity, and the intercrystalline pores of pyrite framboid can also promote the enrichment of hydrocarbons, which has reference significance for shale oil exploration. [ABSTRACT FROM AUTHOR]