Reconstruction of Paleowater Environment and Its Geological Significance of the Dingqinghu Formation in the Lunpo La Basin

As the only basin with industrial oil flow in Tibet, the Lunpola Basin in the study area is rich in oil shale and has great research value. From the analysis of previous studies on the Lunpola basin, it is concluded that the Lunpori area with a large amount of oil shale is an ideal area for studying organic matter enrichment, but the detailed relationship between the paleo‑depositional water environment and organic matter enrichment is not clear, and there are few discoveries and studies on pyrite in the area. In this paper, based on the description of layer section and profile analysis to recover sedimentary phases in Lunpori area, the relationship between organic matter enrichment and paleosol sedimentary environment is carefully explored by the characteristics of pyrite fugitive morphology, grain size and distribution combined with TOC measurement. It is found that the morphology of pyrite and the particle size distribution of strawberry pyrite indicate that the oil shale section was deposited in an anoxic and sulfidic environment, and the TOC content indicates that the oil shale section was enriched with a large amount of organic matter. Combined with previous studies on organic matter sources in the Dingqinghu Formation of the Lunpola Basin, the large amount of organic matter sources and the anoxic and sulfidized sedimentary water environment are the main controlling factors for the organic matter enrichment in the Lunpori oil shale section.