Investigating the roles of magmatic volatiles, ground ice and impact-triggering on a very recent and highly explosive volcanic eruption on Mars

Volcanic activity on Mars has been dominantly effusive. The existence of a young (∼0.05-1 Ma) and well-preserved possible pyroclastic deposit along a segment of the Cerberus Fossae fissures, overlying the effusive lava flows making up the bulk of Elysium Planitia, provides the motivation and opportunity to explore the dynamics of explosive volcanic eruptions on Mars. Here we investigate the subsurface magmatic processes that may have led to magma fragmentation and the explosivity of the eruption forming the deposit. Using numerical models of magma ascent in a volcanic fissure, we show that the dissolved magmatic water with or without suspended crystals is capable of driving the inferred explosive magma fragmentation and the formation of the deposit. We also explore an alternative eruption scenario and show that an intruded dike explosively interacting with melted ground ice might also have generated the deposit. The close proximity of the proposed pyroclastic deposit (15-35 km) to the similarly aged Zunil impact crater suggests the possibility of an impact-triggered volcanic eruption scenario. Using scaling analysis, we find that the high seismic energy density associated with the impact may have been sufficient to trigger a volcanic eruption if a magma chamber was present in the subsurface. These findings have implications for the generation of similar explosive eruptions on Mars and other bodies, as well as the possibility of ongoing magmatic activity on Mars.