Large-scale topography of the North Tibetan ranges as a proxy to contrasted crustal-scale deformation modes

International audienceForming the northern margin of the Cenozoic Himalayan – Tibetan orogen, the area surrounding the Qaidam Basin is a key region to study the mechanisms that govern the long-term evolution of intra-continental orogenic processes. Indeed tectonic deformation in that region involves newly-formed and inherited crustal and lithospheric structures, partition between horizontal and vertical movements, as well as a strong influence from external factors such as climate and erosion. This work proposes a description of the topography and crustal structure of the north Tibet ranges as an insight on their tectonic deformation characteristics. The topographic study includes the integrated analysis of regional topographic profiles, river profiles, slope maps and thermochronology data. The available geophysical, geological and structural data are used to draw regional, crustal-scale geological sections across Northern Tibet to describe the regional crustal structure. We show that three deformation modes are expressed – block uplift, distributed shortening and crustal buckling – in structural compartments that involve either complete mountain ranges or some specific regions inside those ranges. We propose that a new crustal structure may develop parallel to the Altyn Tagh fault, connecting the eastern tip of the Qimen Tagh with the Haiyuan fault, across the Qaidam Basin. Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts Supplementary material: https://doi.org/10.6084/m9.figshare.c.584146