Both Mars and Earth have major topographic features of roughly the same dimension and height. On Mars, the Tharsis rise represents a continent-scale area of approximately 5.5-6 km mean elevation. This topographic feature is second only to the planetary scale Martian dichotomy that separates the thick, elevated crust of the southern hemisphere from the thinner northern lowlands. By comparison, the Tibetan Plateau is Earth’s most extensive, high elevation landmass, also standing at about 5 km mean elevation and a few thousand kilometers in length. We’ve likely not seen anything else like Tibet in Phanerozoic time and it is generally thought that Tibet is large enough to influence both regional and global climate. Both Tibet and Tharsis contain roughly doubly thickened crust and a crustal mass of ~3 x 108 km3, although the Tharsis rise is primarily magmatic in origin and Tibet results from crustal thickening due to continental convergence.
The uplift of such wide, deformed regions depends on the material properties and deformation mechanisms of the deepest part of the lithospheric plates, which exert a primary control on how topography develops. Despite obvious differences in the geologic history and timescale between Mars and Earth, I find it striking that both planets’ most impressive topographic features are so similar in size, extent and regional slope. In particular, the southeast region of Tharsis (Thaumasia plateau) bears strong resemblance in structure and topography to eastern Tibet. High topography and thick crust of eastern Tibet produces long, low-gradient plateau margins that may be caused by the flow of weakened lower (or middle) crust. This has me thinking: if the lower crust flows in Tibet, did it do so on Mars?
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