Explosive mafic volcanoes on Mars and Earth: Deep magma sources and rapid rise rate

Volcanism on Mars is dominated by mafic or ultramafic products. On Earth, mafic volcanics are typically emplaced through small-scale pyroclastic activity such as lava fountaining or Strombolian eruptions, resulting in lava flows. Tyrrhena and Hadriaca Paterae, large, central-vent volcanoes on Mars, however, appear to be primarily constructed of mafic pyroclastic deposits (probably pyroclastic flows), and magma-water (or ice) interactions were not necessarily the cause of these explosive eruptions. The volcanotectonic conditions which generated highly explosive basaltic eruptions on Mars may exist on Earth as well: Masaya Caldera Complex, Nicaragua, has produced large-volume, basaltic ignimbrite, Plinian ash-fall and surge deposits, without overt magma-water interactions. Basaltic magma apparently originated ∼100 km beneath Masaya, and ascended faster than ∼100 cm s^-1 through an established conduit, allowing the magma and exsolved volatiles to reach the surface simultaneously. The combination of deep-sourced magma and rapid rise rate may have also generated ignimbrite-like basaltic pyroclastic deposits at Zavaritski Volcano, Russia, and Ambrym, Vanuatu. Examination of these terrestrial volcanoes may further our understanding of large-scale mafic pyroclastic activity on Mars.