Abstract:Hydrocarbon generation may occur in multiple stages in ancient, complex, deep shale tectonic belts. The accurate reconstruction of the maturity evolution of shale is a prerequisite for the study of the shale gas accumulation mechanism. In this study, the thermal history of the northern margin of the Xuefeng Mountains since the Paleozoic was reconstructed based on a new well drilled by the Geological Survey. The hydrocarbon generation potential of the Lower Cambrian shale is discussed from the perspective of thermal evolution. The results of the inversion of the multiple geologic paleothermometers show that the northern margin of the Xuefeng Mountains had experienced three heating and cooling processes since the Paleozoic. Three thermal evolution peaks successively occurred at the end of the Late Ordovician, late Middle Triassic, and late Early Cretaceous. The maximum temperature decreased over time. The three heating processes were controlled by Early Paleozoic tension and magmatism, Late Paleozoic- Early Mesozoic rapid subsidence, and Early Cretaceous magmatism, respectively. Affected by burial and early thermal events, the shale of the Niutitang Formation experienced peaks in oil generation and cracking in the Cambrian and Early Silurian and reached the mature stage in the Late Ordovician. Subsequently, the first uplift- denudation destroyed the sealing properties of the overburden. This led to the formation of fractures or fault channels, which are conducive to gas diffusion, resulting in the loss of early formed hydrocarbon.