Mesozoic uplift of the Dabashan and Micangshan-Hannan Dome in the South Qinling orogenic belt

The topographic evolution of continental orogens is important for understanding continental orogenic processes, geodynamic mechanisms, and climatic and environmental changes. The Qinling Orogen is a major orogenic belt in China, and its uplift history can provide insights into the tectonic configuration and geodynamics of China and East Asia. Previous studies have shown that the Dabashan and Micangshan-Hannan Dome (MHD) in the South Qinling orogenic belt were uplifted during the Mesozoic. However, the magnitude of the uplift remains unclear. In this study, using sedimentary records in the northern Sichuan Basin and lithospheric flexural modeling, we estimated the magnitude of Mesozoic uplift of the Dabashan and MHD, along with the effective elastic thickness (T-e) of the Sichuan Basin. The Dabashan and MHD were uplifted by approximately 1220 and 880 m during the Middle Jurassic and Early Cretaceous, respectively. Therefore, we propose that the present-day elevation of the Dabashan and MHD is primarily the result of Mesozoic uplift. The differences in the duration and amount of uplift between different tectonic units indicate that the uplift processes and driving mechanisms in the South Qinling orogenic belt were different in the Mesozoic and Cenozoic. Mesozoic uplift was the result of convergence of the North China and South China blocks advanced from east to west, whereas Cenozoic uplift was driven by ongoing indentation of the Indian Plate into Eurasia from southwest to northeast. The lithospheric strength of the northern Sichuan Basin weakened from the Middle Jurassic to Early Cretaceous, and T-e decreased from 73 to 57 km. This may have been caused by the flexure-related bending stresses in the lithosphere that developed due to the large topographic loading.