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Burial and exhumation of the Hoh Xil Basin,northern Tibetan Plateau: Constraints from detrital (U-Th)/He ages |
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| Authors: | Jin-Gen Dai Matthew Fox David L Shuster Jeremy Hourigan Xu Han Ya-Lin Li Cheng-Shan Wang |
| Institution: | 1. School of Earth Science and Resources, and Research Center for Tibetan Plateau Geology, China University of Geosciences, Beijing, China;2. Department of Earth Sciences, University College London, London, UK
Department of Earth and Planetary Science, University of California, Berkeley, USA Berkeley Geochronology Center, Berkeley, USA;3. Department of Earth and Planetary Science, University of California, Berkeley, USA Berkeley Geochronology Center, Berkeley, USA;4. Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA, USA;5. School of Earth Science and Resources, and Research Center for Tibetan Plateau Geology, China University of Geosciences, Beijing, China State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China |
| Abstract: | The uplift and associated exhumation of the Tibetan Plateau has been widely considered a key control of Cenozoic global cooling. The south-central parts of this plateau experienced rapid exhumation during the Cretaceous–Palaeocene periods. When and how the northern part was exhumed, however, remains controversial. The Hoh Xil Basin (HXB) is the largest late Cretaceous–Cenozoic sedimentary basin in the northern part, and it preserves the archives of the exhumation history. We present detrital apatite and zircon (U-Th)/He data from late Cretaceous–Cenozoic sedimentary rocks of the western and eastern HXB. These data, combined with regional geological constraints and interpreted with inverse and forward model of sediment deposition and burial reheating, suggest that the occurrence of ca. 4–2.7 km and ca. 4–2.3 km of vertical exhumation initiated at ca. 30–25 Ma and 40–35 Ma in the eastern and western HXB respectively. The initial differential exhumation of the eastern HXB and the western HXB might be controlled by the oblique subduction of the Qaidam block beneath the HXB. The initial exhumation timing in the northern Tibetan Plateau is younger than that in the south-central parts. This reveals an episodic exhumation of the Tibetan Plateau compared to models of synchronous Miocene exhumation of the entire plateau and the early Eocene exhumation of the northern Tibetan Plateau shortly after the India–Asia collision. One possible mechanism to account for outward growth is crustal shortening. A simple model of uplift and exhumation would predict a maximum of 0.8 km of surface uplift after upper crustal shortening during 30–27 Ma, which is insufficient to explain the high elevations currently observed. One way to increase elevation without changing exhumation rates and to decouple uplift from upper crustal shortening is through the combined effects of continental subduction, mantle lithosphere removal and magmatic inflation. |
| Keywords: | Burial and exhumation Detrital (U-Th)/He thermochronology Hoh Xil Basin Inverse and forward model |