Journal Article

Apatite Geo‐Thermochronology and Geochemistry Constrain Oligocene‐Miocene Growth and Geodynamics of the Northeastern Tibetan Plateau

Lu, Haijian, Wang, Nan, Guo, Chao, Grasemann, Bernhard, Malusà, Marco G., Xiang, Dunfeng, Zhang, Zhiyong, Chew, David, Xiao, Wenjiao, Lease, Richard, Wu, Lin

2025

Overview

Understanding the geodynamics of plateau evolution requires examining the spatial and temporal aspects of mountain building in the northeastern Tibetan Plateau, which are still under debate. Here we integrate apatite geo‐thermochronological and geochemical data from the Oligocene‐Miocene succession of the Xunhua Basin to elucidate the evolution of the regional topography. The results suggest sediment provenance changes, at ca. 28, 20 and 12 Ma, indicating topographic growth of the West Qinling, Laji Shan, and Jishi Shan source areas, respectively. Our findings reveal Oligocene‐Miocene stepwise deformation and middle Miocene stress reorganization within the northeastern Tibetan Plateau. We attribute this to Oligocene lithospheric foundering beneath the south‐central Tibetan Plateau and the middle Miocene initiation of sinistral strike‐slip faults due to the underthrusting of India and North China. This study highlights the roles of lithospheric removal and continental underthrusting in plateau growth, and the value of multi‐proxy apatite analyses in provenance studies. Plain Language Summary The northeastern Tibetan Plateau experienced significant shortening in the last 65 million years due to India‐Eurasia collision, and is thus an ideal region to study how regional topography responds to tectonics. In this study, we have examined the sedimentology and undertaken isotopic dating of apatite grains within the Xunhua Basin. Our results show how the rivers feeding the basin have changed course around 28, 20, and 12 Ma, corresponding to the growth of the West Qinling, Laji Shan, and Jishi Shan mountain ranges, respectively. Our findings, together with evidence for how the rocks in the northeastern Tibetan Plateau have deformed and evidence for the deep structure of the crust from geophysics, suggest deformation progressed from the southern to the northern edges of the northeastern Tibetan Plateau in the last 30 million years. We attribute this to the removal of the Indian Plate beneath the south‐central Tibetan Plateau, and major phases of movement on reverse faults in the northeastern Tibetan Plateau. Furthermore, we identify a stress change in the last 12 million years caused by the major phases of movement on strike‐slip faults in the northeastern Tibetan Plateau. We attribute this to the underthrusting of India and North China plates, respectively. Key Points Apatite provenance data sets reveal provenance changes at ca. 28, 20 and 12 Ma, indicating topographic growth of source areas Stepwise deformation in the NE Tibetan Plateau resulted from Oligocene lithospheric foundering beneath south‐central Tibet Mid‐Miocene strike‐slip fault‐driven stress change in the NE Tibetan Plateau is attributed to the underthrusting of India and North China

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Apatite / continental underthrusting / Deformation / detrital apatite provenance analysis / Evolution / Fault detection / Fault lines / Faults / Geochemistry / Geodynamics / Geophysics / Miocene / Mountains / northeastern Tibetan plateau / Oligocene / Orogeny / plateau growth / Plateaus / Plates / Rivers / Sedimentology / Tectonics / Tectonophysics / Topography