Tectono-thermal evolution of the Micangshan Uplift in the northern Sichuan Basin

The tectono-thermal history of the Micangshan Uplift since the Neoproterozoic was determined in this study based on the combined thermal simulation of the measured zircon (U-Th)/He and apatite fission track ages. The zircon (U-Th)/He ages and apatite fission track ages of the Precambrian samples in the Micangshan Uplift are 138-190 Ma and 106.1-120.6 Ma, respectively. These ages are lower than the corresponding stratigraphic ages or the diagenetic crystallization age, indicating that they effectively record the thermal information in the past. Thermal history modeling results show that the Micangshan Uplift since the Neoproterozoic experienced two rapid cooling events that occurred in Early Jurassic-Early Cretaceous and since late Miocene. They are respectively related to the collisions of the Yangtze-North China plates and India-Eurasia plates, whereas the slow cooling events during the Cretaceous-early Miocene were related to the ancient planation surface. According to the reconstructed burial and thermal history, the source rocks of the Lower Cambrian Qiongzhusi Formation in the Micangshan Uplift entered a high-overmature stage in the Late Triassic due to the high temperature (180-200℃) burial process. This study provides new insights for the tectono-thermal evolution and hydrocarbon accumulation, which are important for guiding further oil and gas exploration in the northern Sichuan Basin.