Mineralogical characterization of acid weathered phyllosilicates with implications for secondary martian deposits

Altheide, T. S.; Chevrier, V. F.; Dobrea, E. Noe

doi:10.1016/j.gca.2010.08.005

Cited by 47 publications

(31 citation statements)

References 61 publications

(86 reference statements)

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“…They show that regional bedrock enrichment in sulfides is sufficient to explain the formation of sulfates locally and that no global acidic event is required. This explains the preservation of carbonates and phyllosilicates that otherwise would have been destroyed by such a late global acidic environment (Fairen et al, 2004;Altheide et al, 2010). This result is positive concerning the search of ancient life on Mars (Navarro-Gonzalez et al, 2010;Bishop et al, 2011), because it suggests that early sediments could have been preserved from acidic weathering in regions with initial low sulfide content.…”

Section: Discussionmentioning

confidence: 89%

Evaluating the role of sulfide-weathering in the formation of sulfates or carbonates on Mars

Dehouck

Chevrier

Gaudin

et al. 2012

Geochimica et Cosmochimica Acta

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Section: Discussionmentioning

confidence: 89%

Evaluating the role of sulfide-weathering in the formation of sulfates or carbonates on Mars

Dehouck

Chevrier

Gaudin

et al. 2012

Geochimica et Cosmochimica Acta

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“…[] also showed a progression of amorphous silica and jarosite transitioning to other sulfates and then to phyllosilicates. Al‐phyllosilicates, such as kaolinite and montmorillonite, can form in acidic volcanic environments and are generally more resistant to acidic and thermal weathering than Fe/Mg‐smectites [ Fialips et al ., ; Ece et al ., ; Altheide et al ., ; Gavin and Chevrier , ], although these are still not present in these experiments. The other possibility is that the phyllosilicates formed a thin layer on grains, which was undetectable with our methods of analysis.…”

Section: Summary Of Experimental Resultsmentioning

confidence: 99%

Laboratory simulations of acid‐sulfate weathering under volcanic hydrothermal conditions: Implications for early Mars

Marcucci

Hynek

2014

JGR Planets

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We have completed laboratory experiments and thermochemical equilibrium models to investigate secondary mineral formation under conditions akin to volcanic, hydrothermal acid-sulfate weathering systems. Our research used the basaltic mineralogy at Cerro Negro Volcano, Nicaragua, characterized by plagioclase, pyroxene, olivine, and volcanic glass. These individual minerals and whole-rock field samples were reacted in the laboratory with 1 molal sulfuric acid at varying temperatures (65, 150, and 200°C), fluid:rock weight ratios (1:1, 4:1, and 10:1), and durations (1–60 days). Thermochemical equilibrium models were developed using Geochemist's Workbench. To understand the reaction products and fluids, we employed scanning electron microscopy/energy dispersive spectroscopy, X-ray diffraction, and inductively coupled plasma-atomic emission spectroscopy. The results of our experiments and models yielded major alteration minerals that include anhydrite, natroalunite, minor iron oxide, and amorphous Al-Si gel. We found that variations in experimental parameters did not drastically change the suite of minerals produced; instead, abundance, size, and crystallographic shape changed. Our results also suggest that it is essential to separate phases formed during experiments from those formed during fluid evaporation to fully understand the reaction processes. Our laboratory reacted and model predicted products are consistent with the mineralogy observed at places on Mars. However, our results indicate that determination of the formation conditions requires microscopic imagery and regional context, as well as a thorough understanding of contributions from both experiment precipitation and fluid evaporation minerals.

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“…Although acid‐saline lakes precipitate kaolinite directly, elsewhere on Mars kaolinite formation has been attributed to top‐down (possibly acid rainfall‐driven) weathering [e.g., Ehlmann et al , 2009; Noe Dobrea and Swayze , 2010], and some of the intercrater kaolinite in northwest Sirenum may have formed in this way (e.g., Figure 31a). If this weathering predated sulfate formation in Columbus crater (which may have occurred under acidic conditions as proposed for Late Noachian/Early Hesperian Mars globally [ Bibring et al , 2006]) then kaolinite could have survived these conditions more effectively than other phyllosilicates (e.g., smectites) due to its greater stability at lower pH [e.g., Altheide et al , 2010b] and its comparatively slow dissolution rate [ Zolotov and Mironenko , 2007]. However, the finding of kaolinite associated with a possible spring mound or silica‐cemented sediments (section 6.2) supports a groundwater‐ (not surface weathering‐) related origin for some Al‐phyllosilicates in this region if these clays are authigenic.…”

Section: Discussionmentioning

confidence: 99%

Columbus crater and other possible groundwater-fed paleolakes of Terra Sirenum, Mars

et al. 2011

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[1] Columbus crater in the Terra Sirenum region of the Martian southern highlands contains light-toned layered deposits with interbedded sulfate and phyllosilicate minerals, a rare occurrence on Mars. Here we investigate in detail the morphology, thermophysical properties, mineralogy, and stratigraphy of these deposits; explore their regional context; and interpret the crater's aqueous history. Hydrated mineral-bearing deposits occupy a discrete ring around the walls of Columbus crater and are also exposed beneath younger materials, possibly lava flows, on its floor. Widespread minerals identified in the crater include gypsum, polyhydrated and monohydrated Mg/Fe-sulfates, and kaolinite; localized deposits consistent with montmorillonite, Fe/Mg-phyllosilicates, jarosite, alunite, and crystalline ferric oxide or hydroxide are also detected. Thermal emission spectra suggest abundances of these minerals in the tens of percent range. Other craters in northwest Terra Sirenum also contain layered deposits and Al/Fe/Mg-phyllosilicates, but sulfates have so far been found only in Columbus and Cross craters. The region's intercrater plains contain scattered exposures of Al-phyllosilicates and one isolated mound with opaline silica, in addition to more common Fe/Mg-phyllosilicates with chlorides. A Late Noachian age is estimated for the aqueous deposits in Columbus, coinciding with a period of inferred groundwater upwelling and evaporation, which (according to model results reported here) could have formed evaporites in Columbus and other craters in Terra Sirenum. Hypotheses for the origin of these deposits include groundwater cementation of crater-filling sediments and/or direct precipitation from subaerial springs or in a deep (∼900 m) paleolake. Especially under the deep lake scenario, which we prefer, chemical gradients in Columbus crater may have created a habitable environment at this location on early Mars.

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Mineralogical characterization of acid weathered phyllosilicates with implications for secondary martian deposits

Cited by 47 publications

References 61 publications

Evaluating the role of sulfide-weathering in the formation of sulfates or carbonates on Mars

Evaluating the role of sulfide-weathering in the formation of sulfates or carbonates on Mars

Laboratory simulations of acid‐sulfate weathering under volcanic hydrothermal conditions: Implications for early Mars

Columbus crater and other possible groundwater-fed paleolakes of Terra Sirenum, Mars

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