Geophysical Investigation of Noctis Volcano on (equatorial) Mars using MOLA, MARSIS, and Numerical Plume Modelling.

Abstract

Most Martian volcanoes have been fed by stationary mantle plumes, leading to the buildup of large shield edifices. A recent investigation on a poorly mapped region, located between equatorial Noctis Labyrinthus and Valles Marineris, revealed a heavily fractured structure, initially interpreted to be an ancient shield volcano called Noctis Mons. This work uses orbital data and geophysical models to unravel the volcano-tectonic formation history of Noctis Mons. Using topographic data, the pre-fracture structure of Noctis Mons is revealed and found to resemble typical small volcanic Martian shields, with a height of ~8694 m. Ancient plume-induced uplift is also observed and compared to an analytical elastic flexure model. Our results indicate Noctis was fed by a ~470 km wide and ~70 km thick mantle plume head. Analyses of radar data suggest a large part of Noctis is made of highly porous (~51%) basalt, suggesting intense explosive activity and potential phreatomagmatism with magma interacting with Valles Marineris water in the Hesperian.