Geochemistry and hydrocarbon potential of Carboniferous–Permian source rocks in eastern Northern Xinjiang

Northern Xinjiang, China, hosts globally recognized Carboniferous–Permian super basins with abundant hydrocarbon resources. However, previous research has predominantly focused on the northwestern region, while the eastern part, despite its significant exploration potential, remains underexplored. Guided by the exploration concept of the “Northern Xinjiang Megalake”, this study investigates key basins in eastern Northern Xinjiang, including the eastern Junggar Basin, Santanghu Basin, and Turpan–Hami Basin. Results indicate that the Lucaogou Formation in the Santanghu Basin and the Pingdiquan Formation in the Junggar Basin share similar characteristics. Both represent good to excellent source rocks dominated by Type II 1 kerogen, currently at the mature stage, with high hydrocarbon generation potential and significant shale oil prospects. Their organic matter is primarily derived from microbial-algal sources, especially Tasmanites and algal mats, with low contributions from higher plants, and deposited under anoxic, slightly brackish to saline conditions. In contrast, the Taodonggou Group in the Turpan-Hami Basin comprises medium to very good quality source rocks, with mixed Type II 1 –III kerogen, also in the mature stage, capable of generating both oil and gas. The organic matter has a complex origin, with contributions from both microbial-algal communities and higher plants, and was deposited in relatively lower salinity waters. Marine source rocks of the Shiqiantan Formation in the Junggar Basin are of medium to very good quality, dominated by Type III kerogen, and are also in the mature stage. Their organic matter is mainly sourced from higher plants, indicating gas-prone characteristics. This study provides the first systematic comparison of source rocks across these basins, offering valuable insights into regional hydrocarbon exploration, as well as into the mechanisms of organic matter enrichment and source rock development in the Carboniferous–Permian systems of Northern Xinjiang.