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

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.