Three-dimensional thermo-mechanical modeling of the Cenozoic uplift of the Tianshan mountains driven tectonically by the Pamir and Tarim

We develop a three-dimensional thermo-mechanical model as an approximate representation of the lithosphere of the Tianshan orogenic belt and adjacent geological units for simulating the uplift mechanism of the Tianshan mountains in the Cenozoic. We apply a velocity boundary condition approximating the northward push of the Pamir and Tarim against the Tianshan block to derive lithospheric deformation of the model. In particular, we investigate systematically the influence of gravity-induced creep deformation on mountain uplift. Our modeling results indicate that: (1) the modeled topographic pattern coincides well with the actual topography, implying that the tectonic push of the Pamir and Tarim can cause significant uplift of the Tianshan mountains; (2) the lithosphere of the Tianshan mountains is mechanically weaker than that of the platforms to the south and north of the Tianshan orogenic belt; and (3) the gravity-induced creep deformation has a significant influence on the process and elevation of mountain uplift. Therefore, when subjected to the tectonic compression resulting from the northward push of the Pamir and Tarim, the relatively weak lithosphere of the Tianshan mountains would deform easily and hence absorb more shortening, resulting in lithospheric thickening and consequent mountain uplift.

► We develop a 3D model for studying the geodynamics of the Tianshan orogenic belt. ► Our modeling incorporates the non-homogeneous rheological structure of lithosphere. ► We investigate the influence of gravity-induced creep deformation on mountain uplift. ► The Tianshan rebuilding is the result of co-extrusion of both the Tarim and Pamir.