Ancient dorsa-related stresses of the Tharsis region on Mars

The early structural history of the Martian Tharsis bulge was studied in terms of a compensation model proposed by Froidevaux and Isacks (1984) proposed for terrestrial plateau uplift. The analysis was based on the regional topographic data on the bulge and the distribution of compressional tectonic features and major volcanoes. The results indicate that the initial phases of the Tharsis formation were dominated by the mantle plume doming, followed by extrusional dome raising; the volcanism became the most important bulge building factor only after thickening of the crust. The formation of the Tharsis bulge and the partial relaxation of this bulge have led to significant horizontal stresses and compression within the peripheral areas. The compressional peripheral zone around the bulge gave rise to dorsa formation while the high bulge crests have been in tensional state.