Supervolcanoes Within an Ancient Volcanic Province in Arabia Terra, Mars

Several irregularly shaped craters located within Arabia Terra, Mars represent a new type of highland volcanic construct and together constitute a previously unrecognized martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae display a range of geomorphic features related to structural collapse, effusive volcanism, and explosive eruptions. Extruded lavas contributed to the formation of enigmatic highland ridged plains in Arabia Terra. Outgassed sulfur and erupted fine-grained pyroclastics from these calderas likely fed the formation of altered, layered sedimentary rocks and fretted terrain found throughout the equatorial region. Discovery of a new type of volcanic construct in the Arabia volcanic province fundamentally changes the picture of ancient volcanism and climate evolution on Mars. Other eroded topographic basins in the ancient Martian highlands that have been dismissed as degraded impact craters should be reconsidered as possible volcanic constructs formed in an early phase of widespread, disseminated magmatism on Mars

The Syrtis Major volcano, Mars: A multidisciplinary approach to interpreting its magmatic evolution and structural development

Very weak crustal magnetic fields over the Syrtis Major volcanic complex imply almost total thermal demagnetization via magmatic intrusions over a large area less than ~4 Ga. We fit a model of these intrusions and the resulting thermal demagnetization to maps of crustal magnetic field strength at 185 km altitude. The best fits are most consistent with a "dog bone"-shaped region of intrusive material, elongated approximately north-south, with an area of ~350,000 km2 and an inferred volume of ~4-19 × 106 km3. Such a large volume is best explained by a long-lived mantle plume beneath the Syrtis edifice. A free-air gravity anomaly high over the Syrtis Major caldera is consistent with dense mafic residue remaining at depth following crystal fractionation that produced the silicic magmas seen at the surface. The elongation of this region is consistent with ascent and north-south emplacement of magma enabled by structures parallel to and associated with the preexisting Isidis impact basin