Tectono-magmatic, sedimentary and hydrothermal history of Arsinoes and Pyrrhae Chaos, Mars

TitleTectono-magmatic, sedimentary and hydrothermal history of Arsinoes and Pyrrhae Chaos, Mars
Publication TypeJournal Article
Year of Publication2020
AuthorsLuzzi E, Rossi APio, Carli C, Altieri F
JournalSubmitted for publication in Journal of Geophysical Research : Planets

Arsinoes and Pyrrhae Chaos are two adjacent chaotic terrains located east to Valles Marineris and west to Arabia Terra, on Mars. In this work we produced a morpho-stratigraphic map of the area, characterized by a volcanic bedrock disrupted into polygonal mesas and knobs (Chaotic Terrain Unit) and two non-disrupted units interpreted as sedimentary and presenting a spectral variation, likely associated to hydrated minerals. The reconstructed geological history of the area starts with the collapse that caused the formation of the chaotic terrains. Since volcano-tectonic evidences are widespread all-over the area (e.g. fissure vents/graben, radial and concentric systems of faults, y-shaped conjunctions, lava flows, pit chains), and an intricate system of lava conduits is hypothesized for the occurrence of such features, we propose the possibility that the whole collapse was caused primarily by volcano-tectonic processes. On Earth, polygonal blocks and systems of concentric + radial fissures are originated in the frame of a particular caldera collapse called chaotic or piecemeal. In the study area on Mars, the chaotic collapse would have been triggered by repeated inflation and deflation of a putative magma chamber in depth under the terrain. In a late stage, after the end of the volcano-tectonic activity, a lacustrine/evaporitic depositional environment could have set, with the deposition of the non-disrupted units. The hydrated minerals found in the periphery of the Chaos could be the result of hydrothermal alteration of the basaltic bedrock.