Modeling the collapse of Hebes Chasma, Valles Marineris, Mars

Abstract

Physical modeling and detailed mapping of Hebes Chasma provide new insights into the crustal composition and origin of the Valles Marineris region of equatorial Mars.Hebes Chasma is a 315-km-long and 8-kmdeep closed depression containing distinctive landforms that include diapirs and extensive allochthonous fl ows that end in pits. A central puzzle of Hebes Chasma is how and where 10 5 km 3 of missing material disappeared. Our physical models tested the hypothesis that the chasma formed by collapse and removal of material from below. Gravity-driven collapse in the models reproduced all the chasma's main landforms as subsidence evolved from early sagging of the upper surface, to inward collapse and removal of material, to emergence of diapirs and low-gradient fl ows. The models and geologic evidence suggest that Hebes Mensa arched upward diapirically and raised deep stratigraphy almost level with the chasma rim. If the chasma indeed collapsed by subsurface drainage as occurred in the models, the upper 8-10 km of deposits at Hebes must have been solid to depths of ~5 km but viscous at greater depths. The materials removed could not have consisted mainly of basalt fl ows; instead, they probably were a mixture of hydrated and nonhydrated salts, water ice, liquid water, and insoluble (likely basaltic) particles. The proportions of these constituents are unknown but constrained because the material drained from the subsiding chasma and apparently contributed to the outburst fl oods released down neighboring Echus Chasma and Kasei Valles.

Evaporite karst in three interior layered deposits in Iani Chaos, Mars

“…4E), and the evaporite karst described in other regions of the Earth (Sauro, 1996;Johnson, 1997;Ford, 1998;Gutiérrez Elorza and Gutiérrez Santolalla, 1998;Maldonado et al, 2000;Ferrarese et al, 2002;Cucchi and Zini, 2003;Parise and Trocino, 2005;Gustavson et al, 2006;Gutiérrez et al, 2008;Stafford et al, 2008;Galve et al, 2009;Di Maggio et al, 2012). Moreover, they strongly resembled the evaporite doline described in other regions of Mars, such as Tithonium Chasma (Baioni et al, 2009;Baioni and Wezel, 2010;Baioni, 2013), Coprates Chasma (Baioni et al, 2011), Hebes Chasma (Grindrod and Balme, 2010;Jackson et al, 2011), Sinus Meridiani (Baioni and Sgavetti, 2013;Baioni et al, 2014) and other regions (McKay and Nedell, 1988;Schaeffer, 1990;Spencer and Fanale, 1990).…”

“…In recent years, the presence of soluble evaporite minerals on Mars -as evidenced by data from the OMEGA instrument (Bibring et al, 2006) on the Mars Express, the Mars Exploration Rovers, and the Compact Reconnaissance Imaging Spectrometer for Mars instrument (Murchie et al, 2007) on the Mars Reconnaissance Orbiter (MRO) -have supported the possible development of evaporite karst similar to that on Earth (Stafford and Boston, 2005) and the presence of karstic terrains with associated caves (Johnston et al, 2006). Recent works based on new highresolution images have demonstrated the presence of karst landforms and processes in Martian evaporite deposits (Baioni et al, 2009;Baioni and Wezel, 2010;Grindrod and Balme, 2010;Jackson et al, 2011;Wezel and Baioni, 2014) and have highlighted the usefulness of the karst landforms as lithological, stratigraphic (Baioni and Sgavetti, 2013), and paleoclimatic (Baioni et al, 2011;Baioni, 2013) markers.…”

Evolution of major sedimentary mounds on Mars: Buildup via anticompensational stacking modulated by climate change

“…This structural consistency with elevation contrasts with the mineralogical variability observed at Gale and elsewhere [ Milliken et al , ]. Sulfate detections specifically correspond to outward dipping layers at Ganges Mensa, Melas Mensa, and Gale's mound [ Chojnacki and Hynek , ; Fueten et al ., ] (Figure ), as well as for Hebes and Candor Mensae [ Schmidt , ; Jackson et al ., ; Fueten et al ., ]. Furthermore, draping layers in SW Melas Chasma show sulfate signatures [ Weitz et al ., ], suggesting that sulfate‐bearing rocks on Mars can form at primary depositional angles that are far from horizontal.…”

“…Hebes Mensa (not shown) shows systematic outward dips, and sulfate detections, but a flat unconformity [ Jackson et al ., ; Schmidt et al ., ; Schmidt , ].…”

Earth and Space 2014

“…It was considered a reasonable stand-in for the first stage of research to be applied eventually to the more basaltic-based martian sandstone, which appears to have lithified through cementation rather than compaction (Bandfield et al, 2013;Jackson et al, 2011;Treiman et al, 1995).…”