Further Evidence for Ancient Volcanism in Northern Arabia Terra, Mars

Much of the Martian surface is volcanic in origin, yet the calculated production volume from identified effusive volcanoes on Mars cannot account for the large abundance of volcanic material across the surface. We have yet to confirm planes-style explosive volcanoes; however, candidate planes-style calderas have been proposed in Arabia Terra as potential sources of the overabundance of volcanic material. These proposed calderas have been identified by their unusual morphologies, but further analysis of the region’s minerology is required to confirm if its origins are indeed volcanic. Here, we test the hypothesis of a volcanic Arabia Terra by investigating the region immediately surrounding Eden Patera, the primary candidate caldera, for spectroscopic and thermodynamic indications of volcanic activity. We searched for spectroscopic indications of silica deposits because silica’s spectral signatures can indicate specific alteration conditions (e.g., hydrothermal versus low-temperature weathering origin). We also investigated pyroxene and smectite deposits, as these are also commonly present in altered volcanic material. Finally, we considered how the thermal inertia of the region relates to the size of the particles making up the surface, as high thermal inertia is consistent with effusive volcanism while low thermal inertia is consistent with explosive volcanism. The results of our spectral and thermal study indicate that there is abundant evidence of weathered hydrated silica across the Arabia Terra region with surface particle sizes similar to that of volcanic ash. Both findings are consistent with volcanic activity in the region, but do not preclude all other surface origins.