India‐Tarim Lithospheric Mantle Collision Beneath Western Tibet Controls the Cenozoic Building of Tian Shan

• Published in: Geophysical research letters Vol. 48; no. 14
• Main Authors: Huangfu, Pengpeng, Li, Zhong‐Hai, Zhang, Kai‐Jun, Fan, Weiming, Zhao, Junmeng, Shi, Yaolin
• Format: Journal Article
• Language: English
• Published: 28.07.2021
• Subjects: far‐field effect; India‐Tarim collision; mountain building; numerical modeling; Tian Shan; western Tibet
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2021GL094561

The ongoing India‐Asia collision principally regulates the Cenozoic tectonic deformation of the Asian interior, and builds a far‐away but active spectacular intraplate orogen—Tian Shan. However, the deep processes and dynamics of far‐field deformation propagation and the resultant Tian Shan building remain ambiguous. Here, we construct systematic numerical models with variable thermo‐rheological properties of the orogen‐featured blocks and convergence rates, which reveal that the far‐field effect of India‐Asia collision on the Tian Shan building is strongly controlled by the direct collision of Indian lithospheric mantle with the rigid Tarim block beneath western Tibet. The model results, together with the well‐established geological and geophysical constraints, not only reconcile the first‐order crustal and lithospheric structures of the western Tibetan plateau and Tian Shan, but also confirm a >30 Myr time lag between the initial India‐Asia collision and the far‐field Tian Shan building. Plain Language Summary The present‐day Tian Shan in the central Asia is one of the world's greatest mountain ranges, and the India‐Asia collision is generally invoked to account for its Cenozoic uplift. However, the Tian Shan range lies ∼1,500 km to the north of the India‐Asia plate boundary at the surface, and its major uplift in the Cenozoic is >30 Myr later than the onset of India‐Asia collision. The physical mechanism for such a long‐distance stress transfer and such a long‐time delay are still poorly understood. In order to solve this problem, we constructed series of large‐scale 2D thermomechanical numerical models, with considering the major lithospheric heterogeneities of the western Tibet‐Tarim‐Tian Shan‐Junggar area. A novel mechanism for the Tian Shan building is proposed based on the comparisons of numerical models and multiple geological and geophysical observations. The new model indicates that the direct contact and collision between Indian and Tarim lithospheric mantles beneath western Tibet dominates the Cenozoic building of the Tian Shan. The new finding links the Tibetan dynamics with far‐field deformation in the Tian Shan range and sheds new light on the extensive continental deformation in the remote continental interior in response to plate tectonic forcing. Key Points A novel mechanism is proposed for the Cenozoic building of Tian Shan based on systematic numerical modeling The Tian Shan building is strongly controlled by the direct collision between Indian and Tarim lithospheric mantles beneath western Tibet The new model reconciles multiple observational constraints and long time lag between the India–Asia collision and Tian Shan reactivation