Early cretaceous-paleocene geothermal gradients and Cenozoic tectono-thermal history of Sichuan basin

Early cretaceous-paleocene geothermal gradients of Sichuan Basin are reconstructed from 27 vitrinite reflectance profiles. Results show that ancient geothermal gradients are between 20~25°C·km-1 and are higher in the eastern and southern regions of the basin than in the western and northern regions. According to comparison of ancient and Current geothermal gradients, geothermal gradients descended in eastern and northeastern but increased in the central and southern regions since the late Mesozoic, while kept unchanged in western Sichuan Basin since the early Cenozoic. According to the tectonic evolution in this area, thermal history of Sichuan Basin in the Mesozoic and Cenozoic was mainly affected by the late Permian tectono-thermal event, the evolution of the lithospheric thickness since the late Mesozoic and the recent active tectonics. The late Permian tectono-thermal event affected most parts of Sichuan Basin. Current active tectonics have significant impact on southern Sichuan, and the evolution of the lithosphere thickness may be the main factors influencing the Mesozoic-Cenozoic thermal history of Sichuan Basin.