Crustal extension in the Ceraunius Fossae, Northern Tharsis Region, Mars

We investigated the Ceraunius Fossae area, Northern Tharsis, in order to obtain quantitative information on the tectonic extension affecting this area. Tectonic structures of the Ceraunius Fossae area have been previously described using Viking images and interpreted as extensional structures. Laser altimetry data (MOLA) can be used to quantitatively investigate these structures with a better resolution. We developed a method to obtain E-W oriented profiles (perpendicular to the main tectonic structures) with a sufficiently high resolution to analyze tectonic structures in spite of the low data density in this direction. We interpreted all the recognizable extensional structures along the profiles, and using a simplified structural model, we estimated tectonic extension along these transects. The extension calculated over the entire profiles is 36 km (e24 = (l1 - l0)/l0 = (910 km - 874 km)/874 km = 0.041) and 42 km (e26 = (730 km - 688 km)/688 km = 0.061) along profile 24 and profile 26, respectively. In the most deformed area, extension reaches the value of 22 km (emax = (l1 -l0)/l0 = (186 km - 164 km)/164 km = 0.134). Since the extension accounted by the topographic doming is negligible, a significant horizontal crustal motion is required to explain the observed extension.