In this study, the sedimentary and geochemical characteristics of oil shale in the Lower and the Upper Member of the Permian Lucaogou Formation in the southeastern Junggar Basin, Northwest China, were investigated. Mineral and bulk chemical compositions, sedimentary facies and distribution of oil shale show that in the Lower Member it is rich in organic matter, but in the Upper Member, organic-poor. The distribution area of deep lake subfacies and oil shale in the Lower Member is larger than that in the Upper Member. The sedimentary modes of these two members were estimated using geochemical parameters, such as Sr/Cu, the chemical index of alteration (CIA), Ni/Co, V/Sc and (C 27 + C 28)/C 29 regular steranes. The organic-rich oil shale in the Lower Member of the Lucaogou Formation formed in the more humid climate and under oxidative conditions, its organic matter derived mainly from algae. On the other hand, the organic-poor oil shale in the formation's Upper Member formed in the humid climate and under more oxidative conditions, while the input of land plants to its organic matter was high and that of algae low.

Based on the results of exploration carried out from 2003 to 2017, oil shales from different areas of the Permian Lucaogou Formation in the JunggarBasin in the northern Bogda Mountains, Northwest China were comparatively investigated, their resources were summarized and development potential was analyzed. The layer of oil shale in the central region of the study area is the thickest, with the greatest cumulative thickness of 198.75 m, while in the western and eastern regions the layer is relatively thin, 66.18 m and 130.00 m, respectively. The total organic carbon (TOC) content of oil shale is 5-35 wt%, whereas the average TOC of oil shale in the central and eastern regions is higher than that in the western region. Based on Hydrogen Index (HI)-Tmax and Pyrolytic Hydrocarbon (S 2 )-TOC diagrams, the organic matter type of oil shale in the central region is mainly I, and in the western and eastern regions mostly II 1 -II 2 and I-II 1 , respectively. In the plane of the whole northern Bogda Mountains, the oil yield of oil shale greatly varies, and the quality of oil shale in the central region is the highest. Of all the studied samples, those with an oil yield ω > 5 wt% account for 70%. Oil shale resources in the study area total 55.241 billion tons (identified resources are 3.921 billion tons), while converted shale oil resources form 5.293 billion tons. Of the 55.241 billion tons, oil shale resources with an oil yield higher than 5 wt% account for 97.26%. Analysis shows that the Yaomoshan Mountain mining area has the greatest development potential, followed by the Lucaogou and Shanghuangshanjie-Panjiazikou mining areas.