Mineralogy of an active eolian sediment from the Namib dune, Gale crater, Mars

Achilles, C. N.; Downs, Robert T.; Ming, D. W.; Rampe, E. B.; Morris, R. V.; Treiman, Allan H.; Morrison, S. M.; Blake, D. F.; Vaniman, D. T.; Ewing, R. C.; Chipera, S. J.; Yen, A. S.; Bristow, T. F.; Ehlmann, B. L.; Gellert, R.; Hazen, Robert M.; Fendrich, Kim V.; Craig, P. I.; Grotzinger, J. P.; Marais, David J. Des; Farmer, Jack D.; Sarrazin, P.; Morookian, John Michael

doi:10.1002/2017je005262

Cited by 123 publications

(209 citation statements)

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“…Dehydroxylation of small amounts of akaganeite detected by CheMin in JK, CB, and possibly WJ could also release some low‐temperature H 2 O [ Ming et al ., ; Vaniman et al ., ; Treiman et al ., ]. Finally, X‐ray amorphous phases, detected by CheMin in all samples [ Bish et al ., ; Vaniman et al ., ; Treiman et al ., ; Achilles et al ., ; Morris et al ., ; Rampe et al ., ; Yen et al ., ], such as poorly crystalline aluminosilicate (e.g., allophane) or amorphous silicate (e.g., opal‐A), and/or nanophase oxides/oxyhydroxides (e.g., ferrihydrite), could evolve H 2 O in the <~450°C range.…”

Section: Resultsmentioning

confidence: 98%

“…The wide temperature water release >~500°C in BK, BS, and GH was attributed to inclusion water in the X‐ray amorphous phases detected in these materials. The X‐ray diffraction amorphous features in BK and GH suggest a more silica rich amorphous fraction than other samples, which exhibits X‐ray diffraction features more consistent with a basaltic glass [ Bish et al ., ; Vaniman et al ., ; Treiman et al , ; Achilles et al ., ; Morris et al ., ; Rampe et al ., ; Yen et al ., ]. Inclusion water in basaltic and rhyolitic (Si‐rich) glass phases can evolve above 500°C [ Westrich , ; Pineau and Javoy , ; McAdam et al ., ].…”

Section: Resultsmentioning

confidence: 98%

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Evolved gas analyses of sedimentary rocks and eolian sediment in Gale Crater, Mars: Results of the Curiosity rover's sample analysis at Mars instrument from Yellowknife Bay to the Namib Dune

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The sample analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, H 2 , SO 2 , H 2 S, NO, CO 2 , CO, O 2 , and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. Coevolved CO 2 (160 ± 248-2373 ± 820 μgC (CO2) /g) and CO (11 ± 3-320 ± 130 μgC (CO) /g) suggest that organic C is present in Gale Crater materials. Five samples evolved CO 2 at temperatures consistent with carbonate (0.32 ± 0.05-0.70 ± 0.1 wt % CO 3 ). Evolved NO amounts to 0.002 ± 0.007-0.06 ± 0.03 wt % NO 3 . Evolution of O 2 suggests that oxychlorine phases (chlorate/perchlorate) (0.05 ± 0.025-1.05 ± 0.44 wt % ClO 4 ) are present, while SO 2 evolution indicates the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H 2 O (0.9 ± 0.3-2.5 ± 1.6 wt % H 2 O) is consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H 2 and H 2 S suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha-Particle X-ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 98%

Evolved gas analyses of sedimentary rocks and eolian sediment in Gale Crater, Mars: Results of the Curiosity rover's sample analysis at Mars instrument from Yellowknife Bay to the Namib Dune

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“…This seems consistent with the results from the MAHLI image analyses, where the white and brown/yellow grains (which could correspond to felsic phases) are more abundant than the darker grains in dump A compared to the other dumps (Figure ). This observation seems also consistent with the mineralogy obtained from CheMin for the <150 μm size fraction (same material as dump A), where the most abundant phase corresponds to feldspars (37%), followed by olivine (26%) [ Achilles et al ., ].…”

Section: Resultsmentioning

confidence: 99%

“…First, it is possible that an amorphous component of similar volatile content is present in lower abundance in the dune material. However, the proportion of amorphous component estimated from CheMin data at Gobabeb is the same, within uncertainties, as at Rocknest sand shadow, i.e., 35 ± 15% versus 27 ± 14% [ Achilles et al ., ; Bish et al ., ]. But the Bagnold dunes may also contain more anhydrous volcanic or impact glass, which would account for a fraction of the amorphous component seen by CheMin.…”

Section: Discussionmentioning

confidence: 99%

“…The enrichment in mafic minerals in the Bagnold dunes' material, evidenced by a small enrichment in olivine in the CheMin analysis (26 wt % of the crystalline phases [ Achilles et al ., ] versus 22 wt % seen in Rocknest) is thus observed in the global ChemCam data set through the enrichment seen in FeO and MnO (Figures a and c). When restricting the analysis to the Bagnold dunes material, MgO is seen to correlate with FeO and MnO, confirming the presence of ferro‐magnesian phases in the dunes such as olivine (Figure ).…”

Section: Discussionmentioning

confidence: 99%

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Geochemistry of the Bagnold dune field as observed by ChemCam and comparison with other aeolian deposits at Gale Crater

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The Curiosity rover conducted the first field investigation of an active extraterrestrial dune. This study of the Bagnold dunes focuses on the ChemCam chemical results and also presents findings on the grain size distributions based on the ChemCam Remote Micro‐Imager and Mars Hand Lens Imager images. These active dunes are composed of grains that are mostly <250 μm. Their composition is overall similar to that of the aeolian deposits analyzed all along the traverse (“Aeolis Palus soils”). Nevertheless, the dunes contain less volatiles (Cl, H, and S) than the Aeolis Palus soils, which appear to be due to a lower content of volatile‐rich fine‐grained particles (<100 μm) or a lower content of volatile‐rich amorphous component, possibly as a result of (1) a lower level of chemical alteration, (2) the removal of an alteration rind at the surface of the grains during transport, (3) a lower degree of interaction with volcanic gases/aerosols, or (4) physical sorting that removed the smallest and most altered grains. Analyses of the >150 μm grain‐size dump piles have shown that coarser grains (150–250 μm) are enriched in the mafic elements Fe and Mn, suggesting a larger content in olivine compared to smaller grains (<150 μm) of the Bagnold dunes. Moreover, the chemistry of soils analyzed in the vicinity of the dunes indicates that they are similar to the dune material. All these observations suggest that the olivine content determined by X‐ray diffraction of the <150 μm grain‐size sample should be considered as a lower limit for the Bagnold dunes.

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Compositional variations in sands of the Bagnold Dunes, Gale crater, Mars, from visible‐shortwave infrared spectroscopy and comparison with ground truth from the Curiosity rover

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During its ascent up Mount Sharp, the Mars Science Laboratory Curiosity rover traversed the Bagnold Dune Field. We model sand modal mineralogy and grain size at four locations near the rover traverse, using orbital shortwave infrared single‐scattering albedo spectra and a Markov chain Monte Carlo implementation of Hapke's radiative transfer theory to fully constrain uncertainties and permitted solutions. These predictions, evaluated against in situ measurements at one site from the Curiosity rover, show that X‐ray diffraction‐measured mineralogy of the basaltic sands is within the 95% confidence interval of model predictions. However, predictions are relatively insensitive to grain size and are nonunique, especially when modeling the composition of minerals with solid solutions. We find an overall basaltic mineralogy and show subtle spatial variations in composition in and around the Bagnold Dunes, consistent with a mafic enrichment of sands with cumulative aeolian‐transport distance by sorting of olivine, pyroxene, and plagioclase grains. Furthermore, the large variations in Fe and Mg abundances (~20 wt %) at the Bagnold Dunes suggest that compositional variability may be enhanced by local mixing of well‐sorted sand with proximal sand sources. Our estimates demonstrate a method for orbital quantification of composition with rigorous uncertainty determination and provide key constraints for interpreting in situ measurements of compositional variability within Martian aeolian sandstones.

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Mineralogy of an active eolian sediment from the Namib dune, Gale crater, Mars

Cited by 123 publications

References 71 publications

Evolved gas analyses of sedimentary rocks and eolian sediment in Gale Crater, Mars: Results of the Curiosity rover's sample analysis at Mars instrument from Yellowknife Bay to the Namib Dune

Evolved gas analyses of sedimentary rocks and eolian sediment in Gale Crater, Mars: Results of the Curiosity rover's sample analysis at Mars instrument from Yellowknife Bay to the Namib Dune

Geochemistry of the Bagnold dune field as observed by ChemCam and comparison with other aeolian deposits at Gale Crater

Compositional variations in sands of the Bagnold Dunes, Gale crater, Mars, from visible‐shortwave infrared spectroscopy and comparison with ground truth from the Curiosity rover

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