Lithospheric thermal regime under the Qinling Orogenic Belt and the Weihe Basin: A transect across the Yangtze and the North China cratons in central China

Abstract

The thermal regime of the lithosphere could be a clue for the processes of geodynamics. Based on the Yuquan-Yulin seismic reflection transect along the Sichuan Basin (Yangtze Craton)–Qinling Orogenic Belt (QOB)–Weihe Basin–Ordos Basin (North China Craton), we modified crustal and mantle lithospheric structures to fit the observed data such as elevation, gravity, geoid height, and heat flow. Then we studied thermal structure, lithospheric thermal thickness and rheological structure of this area. The results suggest that the Moho temperature along the transect ranges from 580 to 740 °C; the thickness of the thermal lithosphere varies from 70 to 190 km. The rheological strength is characterized by the rheological characteristics of “weak crust-strong mantle” in the Sichuan Basin, the south QOB and the Ordos Basin, and “strong crust–weak mantle” in the north QOB and Weihe Basin. The Sichuan Basin has the lowest heat flow, the thickest lithosphere, and the strongest lithospheric strength, while the north QOB and Weihe Basin have the highest heat flow, the thinnest lithosphere, and the weakest lithosphere. The thermal regime of the Sichuan and Ordos basins is affected by the stability of the craton. The thermal regime of the QOB and Weihe Basin respond to the thermal effect of extensional/rifting tectonics. The thermal regime along the transect indicates that this area is mainly affected by the convergence caused by the continental collision of the Indian Plate.