The Coupling of Subduction Dynamics and Large-scale Continental Tectonics during Tethys Closure

Abstract:

The closure of Tethys Ocean and following collision is associated with the most remarkable examples of large-scale continental tectonics of our planet. It is known that this is the result of the coupling between oceanic subduction, where largest tectonic forces are generated, and continents, however why only some segments of the Asian margin display tectonics migration in the interiors remains unknown. Using numerical modeling the dynamics of the subducting and upper plates interactions is probed, emphasizing the role forces such as subducting slabs’ buoyancy, viscous mantle drag, ridge push and far-field forces have in plate margins-interiors coupling. The perturbations to the force balance following slab breakoff, continent subduction and trench land-locking during oceanic closure leads to a range of different strain regimes in the upper plate, from large-scale extrusion to thickening along the collisional margin. The models support the combined interpretation of closing plates, subduction histories and continental tectonics, which is relevant to examples of Asian continent, where similar coupled subduction and upper plate tectonics evolutions are found. It is inferred that the subduction dynamics during Tethys closure strongly controlled the emergence of lithospheric faulting and thickening, indentation, extrusion and extension in the Asian continent.