The surface expression of the Arsia-Mangala Dike, Mars, is controlled by the 'Sawtooth' profile of surface topography.:42nd Lunar and Planetary Science Conference (2011)

摘要

Giant dike swarms are present on Venus, Earth, and Mars [1]. On Mars, sets of graben radiating from centres in the Tharsis volcanic region are taken as evidence for the presence of giant dike swarms [2]. The Mangala Fossa graben system and the related Mangala Valles flood valley probably have had their origins in crustal fracturing caused by the intrusion of one of these dikes [3, 4], which we call the Arsia-Mangala dike. The graben segments formed when the combination of regional extensional tectonic forces and local stresses due to dike injection caused surface subsidence along pairs of inward-facing faults [5]. In the longest graben segment, subsurface aquifer water exploited the graben faults to reach the surface, flood the graben interior, and overflow to erode the Mangala Valles flood channels [4]. Here we propose that 3 other groups of surface features are related to the emplacement of the Arsia-Mangala dike. Specifically, we infer that they are due to asymmetric changes in surface topography in the propagation direction, which the upper edge of the laterally propagating dike was unable to track vertically as the dike was being emplaced, thus leading to the dike top dynamically approaching unusually close to the surface.