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

Abstract

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°C/km to 20-23°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.

Thermo‐tectonic history of the Northeast Sichuan Basin, Southwest China, using apatite fission‐track analysis, vitrinite reflectance, and basin modelling: Implications for hydrocarbon prospectivity

“…The associated palaeo-thermal regimes have changed accordingly (Liu, Tang, Chen, & Tang, 2017). These variations in structural evolution and thermal regimes were of great significance on the future of petroleum systems and main events (Yong, Fan, Lv, Tang, & Wang, 2018;Zhu, Qiu, Liu, Xiao, & Hu, 2019). The frequent Meso-Cenozoic contractional events and associated inverse-structural evolution led to intense regional surface tectonic uplift that started substantially at some time in the middle Lower Cretaceous, as documented by the present tectonic reconstruction.…”

“…For this purpose, the different FT thermochronologic systems that have been used including apatite FT, apatite helium (AHe), Zircon FT, and Zircon helium (ZHe; Shen et al, 2012;Rahn, Wang, & Dunkl, 2019;Zhu et al, 2019). Among them, apatite FT analysis (AFTA) has been widely applied in a number of studies (Fayon & Whitney, 2007;Shen, Mei, & Xu, 2009;Yuan et al, 2006).…”

“…Similarly, the FT ages revealed two possible different cooling initiation times. While the eastern part (sampling sources area of the DB, DK, KW2, and MD9 samples) started experiencing cooling in the Upper Cretaceous (~66 ± 4 Ma), the western part (location area of the MB1-1, PG, and WD-44 samples) was still under subsidence and cooling began only in the Palaeocene 57 ± 3 Ma(Zhu et al, 2019). These values are the averages of the ages of the samples in each part.…”

The Magnitude of Exhumation in the Kidson Sub-Basin, Western Australia, Usingthermal and Compaction Techniques

“…As a method, it is generally accepted as one of the most accurate methods for estimating exhumation using paleo thermal indicators and resolves some of the pitfalls of semi-log plots and empirical depth conversions (Corcoran and Doré, 2005). The technique has been used to quantify exhumation in several basins including the Brooks Range, Alaska (O'sullivan et al, 1995), Northern Australia basins (Duddy et al, 2003), Sichuan Basin, China (Zhu et al, 2019) and Bonaparte Basin, North West Shelf, Australia (Makuluni et al, 2021). The general procedure involved in using this method to estimate the magnitude of exhumation has been described below.…”

The Magnitude of Exhumation in the Kidson Sub-basin, Western Australia, using Thermal and Compaction Techniques

“…As a method, it is generally accepted as one of the most accurate methods for estimating exhumation using paleo thermal indicators and resolves some of the pitfalls of semi-log plots and empirical depth conversions (Corcoran and Doré, 2005). The technique has been used to quantify exhumation in several basins including the Brooks Range, Alaska (O'Sullivan et al, 1995), Northern Australia basins (Duddy et al, 2003), Sichuan Basin, China (Zhu et al, 2019) and Bonaparte Basin, North West Shelf, Australia (Makuluni et al, 2021). The general procedure involved in using this method to estimate the magnitude of exhumation has been described below.…”