Stephanie Shahrzad

and 4 more

The heavily faulted Martian terrains of Ceraunius Fossae and Tractus Fossae, south of the Alba Mons volcano, have previously only been considered as parts of larger tectonic studies of Alba Mons, and the complexity of the faulting remains consequently unclear. As these terrains are in midst of the large Tharsis’ volcanoes, the study of their surface deformation has the potential to help unravel the volcano-tectonic deformation history associated with the growth of Tharsis, as well as decipher details of the responsible magma-tectonic processes. In this study, we distinguish between faults and collapse structures based on image and topographic evidence of pit-crater chains. We mapped ~12,000 faults, which we grouped into 3 distinct fault groups based on orientation, morphology, and relative ages. These show a temporal evolution in the mapped fault orientations from NE to NS to NW, with associated perpendicular stress orientations. Collapse features were also mapped and categorized into 4 different groups: pit-crater chains, catenae, u-shaped troughs and chasma. Examining the 4 collapse structures reveals that they are likely 4 different steps in the erosional evolution of pit-crater chains. Together this revealed a structural history heavily influenced by both local (radial to Alba Mons, Pavonis Mons and Ascraeus Mons) and regional (Tharsis radial) lateral diking, and vertical diking from a proposed Ceraunius Fossae centred magma source. This, along with an updated crater size-frequency distribution analysis of the unit ages, reveals a highly active tectonic and magmatic environment south of Alba Mons, in the Late Amazonian.