Tittle: Wedge-Shaped Southern Indian Continental Margin Without Proper Weakness Hinders Subduction Initiation
Abstract: The closure of a subduction zone with continental terrane collision and accretion is generally thought to be followed by the initiation of a new subduction zone in the neighboring oceanic plate, which is suggested to happen repeatedly during the evolution of Tethyan system. Although the Indian-Asian continental collision has occurred for >50 Myrs, there is still no clear sign for subduction initiation (SI) of the northern Indian oceanic plate, which is a puzzling issue and requires further investigations. This problem is studied here by systematic 3-D thermo-mechanical numerical models with a constant stress boundary condition. The model results indicate that the lack of proper weak zones at passive continental margin plays a critical role in hindering the collapse and SI of the northern Indian oceanic plate. In addition, the wedge-shaped southern Indian continental margin provides an additional resistance for the SI. However, the strain localization with shortening of the Tibetan Plateau does not have a significant effect on the SI of Indian oceanic plate in the current models, which requires further studies with wider Tibetan plate. The numerical results explain why no SI has occurred in the northern Indian Ocean with pushing from the high gravitational potential energy of the uplifted Tibetan Plateau and seafloor spreading in the Northern Indian Ocean, and further predict that the future SI is more likely to occur in the northwestern Indian Ocean than the northeastern region due to continuous counterclockwise rotation of the Indian Continent.
Citation: Zhong, X., & Li, Z.-H. (2022). Wedge-shaped southern Indian continental margin without proper weakness hinders subduction initiation. Geochemistry, Geophysics, Geosystems, 23, e2021GC009998.
