Sulfates hydrating bulk soil in the Martian low and middle latitudes

Karunatillake, S.; Wray, J. J.; Gasnault, O.; McLennan, Scott M.; Rogers, A. D.; Squyres, S. W.; Boynton, W. V.; Skok, J. R.; Ojha, L.; Olsen, Neva F.

doi:10.1002/2014gl061136

Cited by 42 publications

(47 citation statements)

References 58 publications

(90 reference statements)

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“…While the dichotomy is likely early Noachian in age (Frey et al, 2002), the surface ages of these two areas are distinctly different due to a large amount of Hesperian-age material in the northern lowlands (Tanaka et al, 2014). Global assessments of geochemistry also reveal distinctions in the distribution of H 2 O and S in the shallow subsurface soils that may associate with the dichotomy boundary (Karunatillake et al, 2014). In situ results show that correlations and trends among volatile elements (e.g., S, H 2 O, and Cl) can elucidate the amount of alteration (e.g., Haskin et al, 2005), the mineralogy of altered phases (Dehouck et al, 2014), and former aqueous interaction (i.e., presence and migration of fluids, Haskin et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Contrasting Regional Soil Alteration Across the Topographic Dichotomy of Mars

Hood

Karunatillake

Gasnault

et al. 2019

Geophysical Research Letters

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Landscapes on either side of the martian topographic dichotomy bear distinct soil chemistry, but the processes associated with this distinction remain poorly understood. Here, correlation of soil chemistry at global to regional scales is examined with multivariate analysis of Gamma-Ray Spectrometer chemical maps and the Thermal Emission Spectrometer-derived Dust Cover Index (DCI). In the analysis, the northern lowlands show a strong S-Cl correlation, contrasting with the southern highlands, which show a stronger S-H 2 O correlation. These observations suggest aqueous interaction with soils throughout the southern highlands, preferentially dissolving Cl compounds and weakening S-Cl correlation. Strong S-Cl correlations in the northern lowlands suggest less interaction with aqueous H 2 O. Additionally, regional analyses demonstrate that DCI does not correlate with volatile chemistry at smaller scales and that Ca may be an important component of volatile-bearing material. These results provide new evidence for widespread aqueous interaction and possibly alteration of soil in the southern highlands.Plain Language Summary Mars can be divided into two large regions: the northern lowlands and southern highlands, separated by a planet-circling change in elevation known as the topographic dichotomy. The soils that cover the landscape in these two areas appear distinct from one another, although it is unclear what processes cause this distinction. This investigation examines the chemistry of soils on either side of the dichotomy based on Gamma-Ray Spectrometer data, to elucidate changes in soils. The identified changes in correlation of three soil components, sulfur, chlorine, and H 2 O, suggest that much of the southern highlands soils have interacted with water, but fluid interaction occurred far less in the northern lowlands. These findings show that the processes by which water interacts with soils were likely active over larger areas in the southern highlands than previously realized, but such processes were not active after the northern lowlands soils were deposited.

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Section: Introductionmentioning

confidence: 99%

Contrasting Regional Soil Alteration Across the Topographic Dichotomy of Mars

Hood

Karunatillake

Gasnault

et al. 2019

Geophysical Research Letters

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“…Recent identification of sulfates as minerals important to the presence of chemically bound H 2 O both by in situ [ Clark et al ., ; Johnson et al ., ; Lane et al ., ; Wang et al ., ; Wang and Ling , ] and orbital [ Gendrin et al ., ; Murchie et al ., ] missions motivates the search for spatial patterns to hydration state as represented by the H 2 O: S molar ratio in our previous work [ Karunatillake et al ., ]. Hydrated sulfates were discovered in the southern high latitudes using CRISM.…”

Section: Introductionmentioning

confidence: 99%

“…Key processes that influence hydration likely operate in regolith constituents [ McSween et al ., ], rather than outcrops and bedrock, much of which may also be mobile [ Bridges et al ., ] under eolian conditions and support the formation of brine films. For this work, as before [ Karunatillake et al ., ], we term corresponding regolith constituents, typically no larger than cobbles on the Wentworth scale, as bulk soil following the planetary soil definition [ Certini and Ugolini , ] applied with a narrow scope [ Karunatillake et al ., ]. This also ensures consistency with recent work on Mars [ Haskin et al ., ; Morris et al ., ; Newsom et al ., ; Wang et al ., ; McGlynn et al ., ; Meslin et al ., ; Schröder et al ., ; Fedo et al ., ].…”

Section: Introductionmentioning

confidence: 99%

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The association of hydrogen with sulfur on Mars across latitudes, longitudes, and compositional extremes

et al. 2016

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Midlatitudinal hydrated sulfates on Mars may influence brine pH, atmospheric humidity, and collectively water activity. These factors affect the habitability of the planetary subsurface and the preservation of relict biomolecules. Regolith at grain sizes smaller than gravel, constituting the bulk of the Martian subsurface at regional scales, may be a primary repository of chemical alteration, mechanical alteration, and biosignatures. The Mars Odyssey Gamma Ray Spectrometer with hundreds of kilometers of lateral resolution and compositional sensitivity to decimeter depth provides unique insight into this component of the regolith, which we call soil. Advancing the globally compelling association between H2O and S established by our previous work, we characterize latitudinal variations in the association between H and S, as well as in the hydration state of soil. Represented by H2O:S molar ratios, the hydration state of candidate sulfates increases with latitude in the northern hemisphere. In contrast, hydration states generally decrease with latitude in the south. Furthermore, we observe that H2O concentration may affect the degree of sulfate hydration more than S concentration. Limited H2O availability in soil‐atmosphere exchange and in subsurface recharge could explain such control exerted by H2O on salt hydration. Differences in soil thickness, ground ice table depths, atmospheric circulation, and insolation may contribute to hemispheric differences in the progression of hydration with latitude. Our observations support chemical association of H2O with S in the southern hemisphere as suggested by Karunatillake et al. (2014), including the possibility of Fe sulfates as a key mineral group.

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“…Other studies have also used mineralogy and geochemistry to compare gossans to certain martian environments (West et al, 2009). The potentially widespread presence of oxidized iron and sulfur species on Mars (Lane et al, 2015), the contribution of hydrous iron-sulfates to martian regolith hydration (Karunatillake et al, 2014), and the presence of acid-sulfate weathered outcrops, such as the Burns Formation at Meridiani Planum (Squyres et al, 2004), make terrestrial gossans an appropriate analog environment for biosignature studies relevant to the search for evidence of life on Mars (Sobron and Alpers, 2013;Peterson et al, 2014). An appropriate terrestrial gossan for this analog study is the Iron Mountain massive sulfide deposit and gossan in California.…”

Section: Introductionmentioning

confidence: 99%

Preserved Filamentous Microbial Biosignatures in the Brick Flat Gossan, Iron Mountain, California

et al. 2015

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A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes.The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous biogenic filaments could be preserved on Mars in an iron-rich environment analogous to Iron Mountain, with the Pahrump Hills region and Hematite Ridge in Gale Crater as tentative possibilities.

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Sulfates hydrating bulk soil in the Martian low and middle latitudes

Cited by 42 publications

References 58 publications

Contrasting Regional Soil Alteration Across the Topographic Dichotomy of Mars

Contrasting Regional Soil Alteration Across the Topographic Dichotomy of Mars

The association of hydrogen with sulfur on Mars across latitudes, longitudes, and compositional extremes

Preserved Filamentous Microbial Biosignatures in the Brick Flat Gossan, Iron Mountain, California

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