GRS evidence and the possibility of paleooceans on Mars

Dohm, J. M.; Baker, Victor R.; Boynton, W. V.; Fairén, Alberto González; Ferris, J. C.; Finch, Michael; Furfaro, Roberto; Hare, T. M.; Janes, D. M.; Kargel, Jeffrey S.; Karunatillake, S.; Keller, John M.; Kerry, K.; Kim, Kyeong Ja; Komatsu, G.; Mahaney, William C.; Schulze‐Makuch, Dirk; Marinangeli, L.; Ori, G. G.; Ruíz, Javier; Wheelock, Shawn J.

doi:10.1016/j.pss.2008.10.008

Cited by 110 publications

(46 citation statements)

References 123 publications

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“…The use of a wet diabase law is appropriate for a basaltic martian crust and is consistent with extensive evidence for water-related geological activity in early Mars (e.g., Head et al, 2001;Dohm et al, 2009b); moreover, the water amount needed to "wet" the diabase is certainly modest (lower than 1%; see Caristan, 1982). The ductile strength of the mantle lithosphere is calculated for dry and wet olivine dislocation creep rheologies, which give upper and lower limits, respectively, to the surface heat flow.…”

Section: Strength Of the Lithospheresupporting

confidence: 70%

The thermal evolution of Mars as constrained by paleo-heat flows

Ruíz

McGovern

Jiménez‐Díaz

et al. 2011

Icarus

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Section: Strength Of the Lithospheresupporting

confidence: 70%

The thermal evolution of Mars as constrained by paleo-heat flows

Ruíz

McGovern

Jiménez‐Díaz

et al. 2011

Icarus

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“…The first major aim was to discover evidence of past or present water on the surface of Mars and then, more importantly, to search for the presence of life. Water has already been detected on Mars (Bibring et al, 2004;Arvidson et al, 2005;Bellucci et al, 2007), and there is strong evidence that liquid water was a major component of the martian surface in the past (e.g., Malin and Edgett, 2003;Perron et al, 2007;Dohm et al, 2009). Direct evidence of water has also recently been detected by the Phoenix lander in the form of permafrost, as also reported earlier by Boynton et al (2002) based on evidence from remote sensing studies.…”

Section: Introductionsupporting

confidence: 57%

A Conspicuous Clay Ovoid in Nakhla: Evidence for Subsurface Hydrothermal Alteration on Mars with Implications for Astrobiology

Chatzitheodoridis

Haigh

Lyon³

2014

Astrobiology

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A conspicuous biomorphic ovoid structure has been discovered in the Nakhla martian meteorite, made of nanocrystalline iron-rich saponitic clay and amorphous material. The ovoid is indigenous to Nakhla and occurs within a late-formed amorphous mesostasis region of rhyolitic composition that is interstitial to two clinopyroxene grains with Al-rich rims, and contains acicular apatite crystals, olivine, sulfides, Ti-rich magnetite, and a new mineral of the rhoenite group. To infer the origin of the ovoid, a large set of analytical tools was employed, including scanning electron microscopy and backscattered electron imaging, wavelength-dispersive X-ray analysis, X-ray mapping, Raman spectroscopy, time-of-flight secondary ion mass spectrometry analysis, high-resolution transmission electron microscope imaging, and atomic force microscope topographic mapping. The concentric wall of the ovoid surrounds an originally hollow volume and exhibits internal layering of contrasting nanotextures but uniform chemical composition, and likely inherited its overall shape from a preexisting vesicle in the mesostasis glass. A final fibrous layer of Fe-rich phases blankets the interior surfaces of the ovoid wall structure. There is evidence that the parent rock of Nakhla has undergone a shock event from a nearby bolide impact that melted the rims of pyroxene and the interstitial matter and initiated an igneous hydrothermal system of rapidly cooling fluids, which were progressively mixed with fluids from the melted permafrost. Sharp temperature gradients were responsible for the crystallization of Al-rich clinopyroxene rims, rhoenite, acicular apatites, and the quenching of the mesostasis glass and the vesicle. During the formation of the ovoid structure, episodic fluid infiltration events resulted in the precipitation of saponite rinds around the vesicle walls, altered pyrrhotite to marcasite, and then isolated the ovoid wall structure from the rest of the system by depositing a layer of iron oxides/hydroxides. Carbonates, halite, and sulfates were deposited last within interstitial spaces and along fractures. Among three plausible competing hypotheses here, this particular abiotic scenario is considered to be the most reasonable explanation for the formation of the ovoid structure in Nakhla, and although compelling evidence for a biotic origin is lacking, it is evident that the martian subsurface contains niche environments where life could develop.

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“…The paleoshoreline hypothesis is controversial, due to different interpretations proposed for the putative coastal features (see Clifford and Parker, 2001;Ghatan and Zimbelman, 2006 ), but there is a strong support for a distinctive geochemical signature, consistent with aqueous activity and the paleoshoreline demarcations, at the northem plains of Mars (Dohm et al, 2009b ). Moreover, the present-day topography of the Deuteronilus shoreline is acceptably close to an equipotential surface (Head et al, 1999;Carr and Head, 2003 ), and the influence of ocean desiccation on rotation axis and geoid shape could explain the large-scale trends of departure from equipotential surfaces of both Deuteronilus and Arabia shorelines (Perron et al, 2007 ).…”

Section: Regional Variations In the Thermal State Of The Lithospherementioning

confidence: 99%