Palaeomagnetism and detrital zircon U–Pb geochronology of Cretaceous redbeds from central Tibet and tectonic implications

• Published in: Geological journal (Chichester, England) England), 2018-09, Vol.53 (5), p.2315-2333
• Main Authors: Meng, Jun, Zhao, Xixi, Wang, Chengshan, Liu, Hao, Li, Yalin, Han, Zhongpen, Liu, Tao, Wang, Meng, Somerville, I. D.
• Format: Article
• Language: English
• Subjects: Abushan Formation; continental shortening; Convergence; Cretaceous; Crustal shortening; Declination; detrital zircon U–Pb geochronology; Geochronology; Geochronometry; Geological time; Lead; Lhasa–Qiangtang collision; Palaeogeography; Palaeomagnetism; Paleoceanography; Paleomagnetism; Radiometric dating; Terrestrial environments; Tibetan Plateau; Zircon; Zirconium
• ISSN: 0072-1050; 1099-1034
• DOI: 10.1002/gj.3070

Understanding the magnitude of intra‐Asian crustal shortening and the collision age of Lhasa–Qiangtang terranes requires quantitative constraints on the crustal motion. The key to this is defining the palaeogeography of the Tibetan Plateau, which constitutes a poorly known factor over the entire convergence history. New detrital zircon U–Pb geochronological and palaeomagnetic data from the terrestrial Abushan Formation in the Qiangtang terrane demonstrate that central Tibet was located at 27.5 ± 3.0°N during the time interval of ~111–83 Ma. Our results suggest 7.5 ± 2.9° continental shortening has occurred between central Qiangtang and Mongolia during the India–Asia convergence. Declination anomaly indicates the central Qiangtang terrane has experienced significant clockwise rotation (57.3 ± 3.9°) relative to stable Eurasia. The compilation of palaeomagnetic results since the Cretaceous reveals ~8.5° northward drift of the Lhasa terrane from 123 ± 9 to 97 ± 7 Ma and the palaeolatitudinal overlap between the Lhasa and Qiangtang terranes after ~111–103 Ma. Together with the onset age of the terrestrial Abushan Formation, our results provide the youngest timing (ca. ~111–103 Ma) for the closure of the Bangong Meso‐Tethys Ocean, as well as for the final collision of the Lhasa and Qiangtang terranes.