Cooling history of the southwestern Ordos Basin (northern China) since Late Jurassic: Insights from thermochronology and geothermometry

Abstract

Differential tectonothermal evolutionary history of the southern part of the Western Ordos Basin, the southern part of the Liupanshan Mountains, and the northwestern part of the Weibei Uplift was revealed since Late Jurassic by integrating low-temperature thermochronology of apatite fission-track, apatite (U-Th-Sm)/He and zircon (U-Th)/He along with vitrinite reflectance. Inverse modeling results suggest four cooling stages among these three regions since Late Jurassic. Uplift-cooling in the Southwestern Ordos Basin commenced simultaneously with that in the South Liupanshan Mountains in Late Jurassic at ~164–160 Ma. During Late Cretaceous, the entire southwestern region uplifted and cooled since ~118 Ma in the Southwestern Ordos Basin and in the Northwest Weibei Uplift, and since ~105 Ma in the South Liupanshan Mountains. During Early Cenozoic, the Southwestern Ordos Basin and the Northwest Weibei Uplift continued uplift-cooling, while parts of the South Liupanshan Mountains subsided. Since Miocene, a rapid uplift-cooling event of the South Liupanshan Mountains commenced at ~24 Ma, and at ~8 Ma for the Southwestern Ordos Basin and the Northwest Weibei Uplift. In general, the differential evolutionary process of the southwestern North China Plate began in Late Jurassic, continued in Cretaceous and reaching a cooling peak during Miocene with heterogeneous start-time and cooling rate of different sub-units, and mainly controlled by the regional uplift-cooling event of the Qinling-Qilian Orogen in Late Jurassic - Early Cretaceous and by the Qinghai-Tibet Plateau event since Paleocene.