Mars - Thickness of the lithosphere from the tectonic response to volcanic loads

The response to loading of the elastic lithosphere of Mars by seven large volcanic features is estimated based on the hypothesis of a flexural origin for a definable set of load-concentric graben. From the locations of such graben, or from their absence, the lithospheric thickness and flexural rigidity are inferred. For the Tharsis montes, Alba Patera, and Elysium Mons, elastic lithospheric thicknesses at the time of loading range from 20 to 50 km, assuming a Young's modulus of a trillion dyn/sq cm. The thickness exceeded 120 km beneath Olympus Mons and Isidis Planitia. The corresponding ranges in flexural rigidity are approximately 10 to the 30th to 31st dyn cm and greater than 10 to the 32nd dyn cm, respectively. These results indicate a local thinning of the lithosphere beneath portions of the central regions of the Tharsis and Elysium volcanic provinces at the time of loading-induced fracturing.