Apatite fission track reveals uplift-denudation processes of granitoid mountains in East China: a case study of Mount Tianzhushan

Mesozoic granitoid mountains are widely exposed across East China, and their uplift and denudation evolution remain a key challenging scientific issue in the tectonic geomorphology of orogenic belts. Low-temperature thermochronology serves as a powerful tool to quantitatively constrain such geological processes. This approach is adopted in this study to investigate the uplift-denudation history of Mount Tianzhushan. As a UNESCO Global Geopark in southern Anhui Province, China, Mount Tianzhushan is renowned for its eroded granitoid landforms. In this study, the regional uplift and denudation history has been reconstructed for the first time by using the fission track dating (FTD) method. The apatite fission track (AFT) central ages fall into the Paleogene period of the Cenozoic, ranging from 55 to 31 Ma. The positive correlation between AFT ages and sample elevations indicates a pattern of regional integral uplift. Thermal history modeling reveals that its cooling history can be generally divided into three stages: 95–65 Ma, 65–25 Ma, and 25 Ma to the present, characterized by slow cooling, rapid cooling, and moderate cooling, respectively. The average regional cooling rate is calculated at 1.86°C/Ma. The mountain uplift rates vary from 0.041 mm/a to 0.073 mm/a, and the estimated uplift amounts fall into three intervals: 3760–3500 m, 3301–3148 m, and 2840–2620 m, displaying a considerable spatial variability in uplift magnitudes across Mount Tianzhushan. Higher terrain experienced more intense uplift. Regionally, the average uplift rate of Mount Tianzhushan is 0.053 mm/a, with an average denudation rate of 0.034 mm/a, yielding a rate difference of 0.019 mm/a. The average uplift amount relative to eustatic sea level is 3195 m, while its total denudation reaches 2346 m. The 849 m discrepancy is exactly consistent with the modern average elevation of Mount Tianzhushan. FTD provides a solid framework for further research on similar granitoid landform evolution in East China.