Constraining the denudation process in the eastern Sichuan Basin, China using low-temperature thermochronology and vitrinite reflectance data

The temperature history of samples and maximum palaeogeothermal profiles of boreholes were reconstructed based on low-temperature thermochronology and vitrinite reflectance data, and the results provide limits for the timescale and amount of uplift-denudation of the eastern Sichuan Basin. The thermal history showed that the uplifting and cooling of eastern Sichuan Basin began around the Late Cretaceous (approximately 100-80 Ma). The region had experienced a continuous cooling process from the Late Cretaceous until the present, with the geothermal gradient decreasing from 32-36 degrees C/km to 20-23 degrees C/km. The amount of denudation at the Puguang region in north-eastern Sichuan was approximately 2.3 km, whereas that at south-eastern Sichuan was 1.9 km, and the erosion thickness in the eastern Sichuan fold belt that was revealed via the field samples is 2.3 +/- 0.3-2.6 +/- 0.3 km. The north-eastern Sichuan experienced sustained cooling with inconspicuous fluctuations, whereas the thrust belt and the south-eastern Sichuan Basin presented 2-4 stages with different cooling rates. It may indicate that the eastern Sichuan fold belt experienced a complex structural evolution, characterized by episodic upliftings and deformations since Late Cretaceous, while a different and gentle deformation took place in the northeastern Sichuan Basin.