Thermal Lithospheric Thickness of the Sichuan Basin and its Geological Implications

Abstract

Thermal lithospheric thickness is an important parameter in studying the tectonic-thermal evolution of basins and plate dynamics. Based on the measured geothermal data and thermophysical properties of the rocks, the thermal lithospheric thickness of the Sichuan Basin was calculated according to the principles of heat conduction in the crust and lithospheric mantle. The calculation results revealed that the thickness of the thermal lithosphere in the Sichuan Basin is 140-190 km and is unevenly distributed. The thickness of the thermal lithosphere in central Sichuan and southwestern Sichuan is less than 160 km, while that in the western Sichuan depression and eastern Sichuan is larger (~180 km). The distribution of the thermal lithospheric thickness in the basin has a good correlation with the geological units and the thickness of the sedimentary layers. The thickness of the thermal lithosphere in the depression area, which has thick sedimentary layers and the fault-fold zone with shallow crustal deformation and thickening, are larger than that in the basement uplifted area, which has thin sedimentary layers. The calculated thermal lithospheric thickness is in good agreement with the geophysical data and reflects the stable conduction temperature field in the Sichuan Basin. The present thermal regime and thermal lithospheric thickness of the Sichuan Basin indicate that flexural thickening of the lithosphere occurred in the eastern Sichuan fault-fold belt and the Longmen Mountain-Western Sichuan depression foreland basin system, while asthenospheric uplift occurred in the central Sichuan region, which were the result of the expansion of the Xuefeng orogeny from the east and the compression of the Tibetan Plateau from the west.

A Comparison Study of Synkinematic Illite Isolation, Quantitative X‐ray Powder Diffraction, and K‐Ar Dating for Direct Fault Gouge Analyses

“…The natural fault gouges studied were collected from coseismic surface ruptures of the Longmen Shan fault belt (LSFB) caused by the 2008 Wenchuan Ms 8.0 earthquake, to test the efficacy of our sample preparation approaches. The 2008 Wenchuan earthquake produced two surface ruptures along the Yingxiu-Beichuan fault (YBF) and Guanxian-Anxian fault (GAF) (Fu et al, 2011;Li et al, 2013;Zhu et al, 2022) along the eastern boundary of the Tibetan Plateau (Fig. 1a).…”

Estimation of terrestrial heat flow in hydrothermally active areas based on long-term bedrock temperature observations: a case study of northwestern Yunnan, China

“…The terrestrial heat flux is a fundamental output of the dynamic solid Earth's heat engine (Davies, 2013). Therefore, a better understanding of terrestrial heat flow provides a constraint on the thermal structure of the crust and lithospheric mantle and hence on lithospheric rheology (Liu et al, 2005;Furlong et al, 2013;He, 2015;Liu et al, 2016;Njinju et al, 2019;Zhu et al, 2022). The estimation of terrestrial heat flow can also play a role in applications such as hydrocarbon, geothermal and mineral exploration (Zhang C. et al, 2018;Prol-Ledesma and Morán-Zenteno, 2019).…”