Diachronous Tibetan Plateau landscape evolution derived from lava field geomorphology

Evolution of the Tibetan Plateau is important for understanding continental tectonics because of the plateau’s exceptional elevation (~5 km above sea level) and crustal thickness (~70 km). Patterns of long-term landscape evolution can constrain tectonic processes, but have been hard to quantify, in contrast to established data sets for strain, exhumation, and paleo-elevation. This study analyzes the relief of the bases and tops of 17 Cenozoic lava fields on the central and northern Tibetan Plateau. Analyzed fields have typical lateral dimensions of tens of kilometers, and so have an appropriate scale for interpreting tectonic geomorphology. Fourteen of the fields have not been deformed since eruption. One field is cut by normal faults; two others are gently folded, with limb dips 3 km) exhumation and plateau landscape development. This diachronous process took place between ~32.5°N and ~36.5°N and between ca. 40 Ma and ca. 10 Ma, advancing northwards at a long-term rate of ~15 km/m.y. Results are consistent with incremental northward growth of the plateau, rather than a stepwise evolution or synchronous uplift.