Multi‐Stage Growth in the North Margin of the Qinling Orogen, Central China, Revealed by Both Low‐Temperature Thermochronology and River Profile Inversion

Abstract

AbstractThe Qinling orogen formed as a result of the convergence between North and South China Blocks and was reactivated by India‐Asia collision and/or Pacific subduction in the Cenozoic. We presented new apatite U‐Th/He age‐elevation profiles in the northern margin of the Qinling Mountains and observed Oligocene pulse of rapid exhumation. Thermal modeling on our data (by the HeFTy program) revealed another two early cooling episodes, that is, in the early Cretaceous and the early Cenozoic. Besides, increases in the mountain uplift rates since the late Miocene were retrieved from a linear inversion on modern channel longitudinal profiles. Combining previous studies, we proposed possible geodynamic regimes underlying the multi‐stage cooling and exhumation pattern in the north Qinling. We interpreted the early Cretaceous cooling as a result of the southward intracontinental subduction of North China Block beneath South China Block. The early Cenozoic exhumation was under the Pacific back‐arc extension background and might be influenced by a far‐filed response to Eurasian and Indian plate's collision. The Oligocene phase could be mostly driven by West Pacific plate subduction beneath East Asia. And, the mountain uplift since the late Miocene could be triggered by the growth and expansion of the North East Tibetan Plateau.