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20 pages, 3580 KiB

Open AccessArticle

Anaerobic Microscopic Analysis of Ferrous Saponite and Its Sensitivity to Oxidation by Earth’s Air: Lessons Learned for Analysis of Returned Samples from Mars and Carbonaceous Asteroids

by Natsumi Noda, Shohei Yamashita, Yoshio Takahashi, Megumi Matsumoto, Yuma Enokido, Kana Amano, Takahiro Kawai, Hiroshi Sakuma, Keisuke Fukushi, Yasuhito Sekine and Tomoki Nakamura

Minerals 2021, 11(11), 1244; https://doi.org/10.3390/min11111244 - 9 Nov 2021

Cited by 4 | Viewed by 2907

Abstract

Ferrous saponite is a secondary mineral that can be used to reveal the redox state of past aqueous environments on Mars. In mineralogical analyses for ferrous saponite formed in laboratory simulations or contained in future returned samples from Mars, its oxidation by the [...] Read more.

Ferrous saponite is a secondary mineral that can be used to reveal the redox state of past aqueous environments on Mars. In mineralogical analyses for ferrous saponite formed in laboratory simulations or contained in future returned samples from Mars, its oxidation by the Earth’s air could be problematic due to the high redox sensitivity. Here, we performed micro X-ray diffraction and scanning transmission X-ray microscopy analyses for a single particle of synthesized ferrous saponite without any exposure to air. The sample was reanalyzed after air exposure for 10–18 h to assess the adequacy of our anoxic preparation/measurement methods and the impacts of air on the sample. We found that the crystal structures agreed with ferrous saponite, both before and after air exposure; however, ferrous iron in saponite was partially oxidized, at least until 0.1–1 μm from the surface, after air exposure at the submicron scale, forming micro-vein-like Fe(III)-rich features. Together with our results of infrared spectroscopy of ferrous saponite, we showed that oxidation of octahedral iron occurred rapidly and heterogeneously, even in a short time of air exposure without any structural rearrangement. Since ferrous saponite is expected to exist on carbonaceous asteroids and icy dwarf planets, our methodology is also applicable to mineralogical studies of samples returned from these bodies. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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25 pages, 59664 KiB

Open AccessArticle

A New Constraint on the Physicochemical Condition of Mars Surface during the Amazonian Epoch Based on Chemical Speciation for Secondary Minerals in Martian Nakhlites

by Hiroki Suga, Keika Suzuki, Tomohiro Usui, Akira Yamaguchi, Oki Sekizawa, Kiyofumi Nitta, Yasuo Takeichi, Takuji Ohigashi and Yoshio Takahashi

Minerals 2021, 11(5), 514; https://doi.org/10.3390/min11050514 - 13 May 2021

Cited by 5 | Viewed by 3688

Abstract

Iddingsite in Martian nakhlites contains various secondary minerals that reflect water–rock interaction on Mars. However, the formation processes of secondary Fe minerals in iddingsite are unclear because they include carbonates precipitated under reductive and alkaline conditions and sulfates that are generally precipitated under [...] Read more.

Iddingsite in Martian nakhlites contains various secondary minerals that reflect water–rock interaction on Mars. However, the formation processes of secondary Fe minerals in iddingsite are unclear because they include carbonates precipitated under reductive and alkaline conditions and sulfates that are generally precipitated under oxidative and acidic conditions. Mineral types cannot coexist under equilibrium. Herein, we characterize the carbonate phase of meteorite Yamato 000593 as siderite and Mn-bearing siderite via field-emission electron probe microanalyzer (FE-EPMA). Then, we examined the distribution and speciation of trace Cr and S within the carbonates through synchrotron micro-focused X-ray fluorescence-X-ray absorption fine structure and scanning transmission X-ray microscopy (μ-XRF-XAFS/STXM) analysis to estimate the transition history of Eh-pH conditions during siderite formation to explain the coexistence of carbonate and sulfate phases in the nakhlite vein. Specifically, the distribution and speciation of S in the mesostasis and carbonate phases and the heterogeneous distribution of Mn-FeCO₃ incorporating Cr(III) in the carbonate constrain the Eh-pH condition. The conditions and transition of the fluid chemistry determined herein based on speciation of various elements provide a new constraint on the physicochemical condition of the water that altered the nakhlite body during the Amazonian epoch. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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20 pages, 4925 KiB

Open AccessArticle

Assessment of Sulfate Sources under Cold Conditions as a Geochemical Proxy for the Origin of Sulfates in the Circumpolar Dunes on Mars

by Anna Szynkiewicz and Janice L. Bishop

Minerals 2021, 11(5), 507; https://doi.org/10.3390/min11050507 - 11 May 2021

Cited by 6 | Viewed by 2878

Abstract

Determining aqueous sulfate sources in terrestrial cold environments can provide an insight into the surface hydrological conditions and sulfur cycle on Mars. In this study, we analyzed sulfur and oxygen isotope compositions of secondary sulfate salts (e.g., gypsum, thenardite) in the surficial sediments [...] Read more.

Determining aqueous sulfate sources in terrestrial cold environments can provide an insight into the surface hydrological conditions and sulfur cycle on Mars. In this study, we analyzed sulfur and oxygen isotope compositions of secondary sulfate salts (e.g., gypsum, thenardite) in the surficial sediments and soils of the McMurdo Dry Valleys (MDV), Antarctica to determine contributions of sulfate from bedrock chemical weathering and atmospheric deposition under persistent dry polar conditions. The sulfate showed wider variation of δ³⁴S (+15.8‰ to +32.5‰) compared to smaller ranges of δ¹⁸O (−8.9‰ to −4.1‰). In contrast, the δ³⁴S of bedrock sulfide showed significantly lower and consistent values across the studied area (−0.6‰ to +3.3‰). Based on the δ³⁴S trends, sulfide weathering may contribute up to 20–50% of secondary sulfate salts in the MDV. While the remaining 50–80% of sulfate inputs may originate from atmospheric deposition (e.g., sea aerosols, dimethulsulfide oxidation), the subglacial brines derived by relicts of seawater and/or lake/pond water influenced by microbial sulfate reduction could also be important sulfate endmembers particularly in the Antarctic lowland thaw zones. Additional field observations of frost, ponding water, and thin gypsum crusts on the terrestrial gypsum dunes at White Sands supports reactivity of gypsum on the surface of these dunes during cold winter conditions. Combined with our improved geochemical model of the sulfur cycle for cold Antarctic settings, we propose that transient liquid water or frost was available in near-surface environments at the time of gypsum formation in the north polar region on Mars. Ice and/or water interaction with basaltic sand of the basal unit (paleo-erg) would have enhanced leaching of sulfate from both sulfide oxidation and atmospheric deposition and resulted in formation of secondary gypsum salts. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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21 pages, 3575 KiB

Open AccessArticle

Composition of the Primordial Ocean Just after Its Formation: Constraints from the Reactions between the Primitive Crust and a Strongly Acidic, CO₂-Rich Fluid at Elevated Temperatures and Pressures

by Hisahiro Ueda and Takazo Shibuya

Minerals 2021, 11(4), 389; https://doi.org/10.3390/min11040389 - 6 Apr 2021

Cited by 14 | Viewed by 5583

Abstract

The Hadean was an enigmatic period in the Earth’s history when ocean formation and the emergence of life may have occurred. However, minimal geological evidence is left from this period. To understand the primordial ocean’s composition, we focused on the ocean’s formation processes [...] Read more.

The Hadean was an enigmatic period in the Earth’s history when ocean formation and the emergence of life may have occurred. However, minimal geological evidence is left from this period. To understand the primordial ocean’s composition, we focused on the ocean’s formation processes from CO₂- and HCl-bearing water vapor in the high-temperature atmosphere. When the temperature of the lower atmosphere fell below the critical point, high-temperature rain reached the ground surface. Then, hydrothermal reactions between the subcritical fluid and primordial crust started. Eventually, a liquid ocean emerged on the completely altered crust as the temperature decreased to approximately 25 °C. Here, we conducted two experiments and modeling to simulate the reactions of hypothetical primordial crustal rock (basalt or komatiite). The results indicate that the primordial ocean was mildly acidic and rich in CO₂, Mg, and Ca relative to Na, irrespective of the rock type, which is different from the modern equivalents. Therefore, unlike the present seawater, the primordial seawater could have been carbonic, bitter, and harsh rather than salty. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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22 pages, 3151 KiB

Open AccessEditor’s ChoiceArticle

Thermodynamic Constraints on Smectite and Iron Oxide Formation at Gale Crater, Mars: Insights into Potential Free Energy from Aerobic Fe Oxidation in Lake Water–Groundwater Mixing Zone

by Sakiko Kikuchi and Takazo Shibuya

Minerals 2021, 11(4), 341; https://doi.org/10.3390/min11040341 - 25 Mar 2021

Cited by 6 | Viewed by 3229

Abstract

The presence of saponite and iron oxides in Sheepbed mudstone of Yellowknife Bay at Gale crater on Mars is considered as evidence of a habitable fluvio-lacustrine environment for chemolithoautotrophy. However, the energetic availability for metabolic reactions is poorly constrained. Herein, we propose the [...] Read more.

The presence of saponite and iron oxides in Sheepbed mudstone of Yellowknife Bay at Gale crater on Mars is considered as evidence of a habitable fluvio-lacustrine environment for chemolithoautotrophy. However, the energetic availability for metabolic reactions is poorly constrained. Herein, we propose the possible mixing of surface water and groundwater that (i) explains the formation of magnetite and hematite detected in Sheepbed mudstone and (ii) may work as a potential habitable zone for aerobic Fe²⁺-oxidizing microbes. Our thermodynamic modeling of water–rock reactions revealed that the formation of abundant saponite in Sheepbed mudstone may occur under various conditions of water-to-rock mass ratios, temperatures (5–200 °C), and initial fluid compositions. In contrast, the formation of iron oxides in the mudstone can be explained only by the mixing of Fe²⁺-rich groundwater and more oxidized surface waters, where the Fe²⁺-rich groundwater can be generated by the low-temperature water–rock reactions with a CO₂-bearing initial fluid. The calculated bioavailable energy of aerobic Fe²⁺ oxidation in the fluid-mixing zone on Mars is similar to that estimated for a fluid-mixing zone on Earth actually inhabited by aerobic Fe²⁺-oxidizing microbes. The findings will contribute to a better understanding of potential habitability on Mars. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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30 pages, 6216 KiB

Open AccessArticle

Stable Abiotic Production of Ammonia from Nitrate in Komatiite-Hosted Hydrothermal Systems in the Hadean and Archean Oceans

by Manabu Nishizawa, Takuya Saito, Akiko Makabe, Hisahiro Ueda, Masafumi Saitoh, Takazo Shibuya and Ken Takai

Minerals 2021, 11(3), 321; https://doi.org/10.3390/min11030321 - 19 Mar 2021

Cited by 10 | Viewed by 4006

Abstract

Abiotic fixation of atmospheric dinitrogen to ammonia is important in prebiotic chemistry and biological evolution in the Hadean and Archean oceans. Though it is widely accepted that nitrate (NO₃⁻) was generated in the early atmospheres, the stable pathways of ammonia [...] Read more.

Abiotic fixation of atmospheric dinitrogen to ammonia is important in prebiotic chemistry and biological evolution in the Hadean and Archean oceans. Though it is widely accepted that nitrate (NO₃⁻) was generated in the early atmospheres, the stable pathways of ammonia production from nitrate deposited in the early oceans remain unknown. This paper reports results of the first experiments simulating high-temperature, high-pressure reactions between nitrate and komatiite to find probable chemical pathways to deliver ammonia to the vent–ocean interface of komatiite-hosted hydrothermal systems and the global ocean on geological timescales. The fluid chemistry and mineralogy of the komatiite–H₂O–NO₃⁻ system show iron-mediated production of ammonia from nitrate with yields of 10% at 250 °C and 350 °C, 500 bars. The komatiite–H₂O–NO₃^– system also generated H₂-rich and alkaline fluids, well-known prerequisites for prebiotic and primordial metabolisms, at lower temperatures than the komatiite–H₂O–CO₂ system. We estimate the ammonia flux from the komatiite-hosted systems to be 10⁵–10¹⁰ mol/y in the early oceans. If the nitrate concentration in the early oceans was greater than 10 μmol/kg, the long-term production of ammonia through thermochemical nitrate reduction for the first billion years might have allowed the subsequent development of an early biosphere in the global surface ocean. Our results imply that komatiite-hosted systems might have impacted not only H₂-based chemosynthetic ecosystems at the vent-ocean interface but also photosynthetic ecosystems on the early Earth. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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17 pages, 3293 KiB

Open AccessArticle

Thermodynamic Impact of Mineral Surfaces on Amino Acid Polymerization: Aspartate Dimerization on Two-Line Ferrihydrite, Anatase, and γ-Alumina

by Norio Kitadai, Kumiko Nishiuchi and Wataru Takahagi

Minerals 2021, 11(3), 234; https://doi.org/10.3390/min11030234 - 25 Feb 2021

Cited by 4 | Viewed by 3149

Abstract

The presence of amino acids in diverse extraterrestrial materials has suggested that amino acids are widespread in our solar system, serving as a common class of components for the chemical evolution of life. However, there are a limited number of parameters available for [...] Read more.

The presence of amino acids in diverse extraterrestrial materials has suggested that amino acids are widespread in our solar system, serving as a common class of components for the chemical evolution of life. However, there are a limited number of parameters available for modeling amino acid polymerization at mineral–water interfaces, although the interfacial conditions inevitably exist on astronomical bodies with surface liquid water. Here, we present a set of extended triple-layer model parameters for aspartate (Asp) and aspartyl-aspartate (AspAsp) adsorptions on two-line ferrihydrite, anatase, and γ-alumina determined based on the experimental adsorption data. By combining the parameters with the reported thermodynamic constants for amino acid polymerization in water, we computationally demonstrate how these minerals impact the AspAsp/Asp equilibrium over a wide range of environmental conditions. It was predicted, for example, that two-line ferrihydrite strongly promotes Asp dimerization, leading to the AspAsp/Asp ratio in the adsorbed state up to 41% even from a low Asp concentration (0.1 mM) at pH 4, which is approximately 5 × 10⁷ times higher than that attainable without mineral (8.5 × 10⁻⁶%). Our exemplified approach enables us to screen wide environmental settings for abiotic peptide synthesis from a thermodynamic perspective, thereby narrowing down the geochemical situations to be explored for life’s origin on Earth and Earth-like habitable bodies. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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16 pages, 52667 KiB

Open AccessFeature PaperArticle

EXAFS Determination of Clay Minerals in Martian Meteorite Allan Hills 84001 and Its Implication for the Noachian Aqueous Environment

by Ryoichi Nakada, Gaku Tanabe, Iori Kajitani, Tomohiro Usui, Masashi Shidare and Tetsuya Yokoyama

Minerals 2021, 11(2), 176; https://doi.org/10.3390/min11020176 - 8 Feb 2021

Cited by 2 | Viewed by 3655

Abstract

The aqueous environment of ancient Mars is of significant interest because of evidence suggesting the presence of a large body of liquid water on the surface at ~4 Ga, which differs significantly from the modern dry and oxic Martian environment. In this study, [...] Read more.

The aqueous environment of ancient Mars is of significant interest because of evidence suggesting the presence of a large body of liquid water on the surface at ~4 Ga, which differs significantly from the modern dry and oxic Martian environment. In this study, we examined the Fe-bearing minerals in the 4 Ga Martian meteorite, Alan Hills (ALH) 84001, to reveal the ancient aqueous environment present during the formation of this meteorite. Extended X-ray absorption fine structure (EXAFS) analysis was conducted to determine the Fe species in ALH carbonate and silica glass with a high spatial resolution (~1–2 μm). The μ-EXAFS analysis of ALH carbonate showed that the Fe species in the carbonate were dominated by a magnesite-siderite solid solution. Our analysis suggests the presence of smectite group clay in the carbonate, which is consistent with the results of previous thermochemical modeling. We also found serpentine in the silica glass, indicating the decrease of water after the formation of carbonate, at least locally. The possible allochthonous origin of the hematite in the carbonate suggests a patchy redox environment on the ancient Martian surface. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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26 pages, 5675 KiB

Open AccessArticle

Hydrogeochemical Study on Closed-Basin Lakes in Cold and Semi-Arid Climates of the Valley of the Gobi Lakes, Mongolia: Implications for Hydrology and Water Chemistry of Paleolakes on Mars

by Yasuhito Sekine, Takuma Kitajima, Keisuke Fukushi, Baasansuren Gankhurel, Solongo Tsetsgee, Davaadorj Davaasuren, Haruna Matsumiya, Takufumi Chida, Maya Nakamura and Noriko Hasebe

Minerals 2020, 10(9), 792; https://doi.org/10.3390/min10090792 - 8 Sep 2020

Cited by 13 | Viewed by 4287

Abstract

Previous studies suggested that, generally, the climate of early Mars would have been semi-arid when the surface temperatures were above freezing. On early Mars, closed-basin lakes would have been created; however, the hydrogeochemical cycles of the lake systems are poorly constrained. Here we [...] Read more.

Previous studies suggested that, generally, the climate of early Mars would have been semi-arid when the surface temperatures were above freezing. On early Mars, closed-basin lakes would have been created; however, the hydrogeochemical cycles of the lake systems are poorly constrained. Here we report results of our field surveys to terrestrial analogs of closed-basin lake systems that developed in cold and semi-arid climates: The Valley of the Gobi Lakes of Mongolia. Our results show that groundwater plays a central role not only in hydrology, but also in geochemical cycles in the lake systems. We find that groundwater predominantly flows into the lakes through local seepage and regional flows in semi-arid climates. Through the interactions with calcite-containing soils, local groundwater seepage provides Ca²⁺ and HCO₃⁻ to the lakes. In the wetland located in between the lakes, high-salinity shallow pools would provide Cl⁻ and Na⁺ to the groundwater through infiltration. If similar processes occurred on early Mars, local seepage of groundwater would have provided magnesium and alkalinity to the early Jezero lakes, possibly leading to authigenic precipitation of lacustrine carbonates. On early Mars, infiltration of surface brine may have transported salts and oxidants on the surface to lakes via regional groundwater flows. We suggest that inflows of multiple types of groundwater in semi-arid climates could have caused redox disequilibria in closed-basin lakes on early Mars. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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21 pages, 3357 KiB

Open AccessFeature PaperArticle

Capacity of Chlorate to Oxidize Ferrous Iron: Implications for Iron Oxide Formation on Mars

by Kaushik Mitra, Eleanor L. Moreland and Jeffrey G. Catalano

Minerals 2020, 10(9), 729; https://doi.org/10.3390/min10090729 - 19 Aug 2020

Cited by 19 | Viewed by 7995

Abstract

Chlorate is an important Cl-bearing species and a strong potential Fe(II) oxidant on Mars. Since the amount of oxychlorine species (perchlorate and chlorate) detected on Mars is limited (<~1 wt.%), the effectiveness of chlorate to produce iron oxides depends heavily on its oxidizing [...] Read more.

Chlorate is an important Cl-bearing species and a strong potential Fe(II) oxidant on Mars. Since the amount of oxychlorine species (perchlorate and chlorate) detected on Mars is limited (<~1 wt.%), the effectiveness of chlorate to produce iron oxides depends heavily on its oxidizing capacity. Decomposition of chlorate or intermediates produced during its reduction, before reaction with Fe(II) would decrease its effective capacity as an oxidant. We thus evaluated the capacity of chlorate to produce Fe(III) minerals in Mars-relevant fluids, via oxidation of dissolved Fe(II). Each chlorate ion can oxidize 6 Fe(II) ions under all conditions investigated. Mass balance demonstrated that 1 wt.% chlorate (as ClO₃⁻) could produce approximately 6 to 12 wt.% Fe(III) or mixed valent mineral products, with the amount varying with the formula of the precipitating phase. The mineral products are primarily determined by the fluid type (chloride- or sulfate-rich), the solution pH, and the rate of Fe(II) oxidation. The pH at the time of initial mineral nucleation and the amount of residual dissolved Fe(II) in the system exert important additional controls on the final mineralogy. Subsequent diagenetic transformation of these phases would yield 5.7 wt.% hematite per wt.% of chlorate reacted, providing a quantitative constraint on the capacity of chlorate to generate iron oxides on Mars. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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15 pages, 1326 KiB

Open AccessArticle

In Situ Formation of Monohydrocalcite in Alkaline Saline Lakes of the Valley of Gobi Lakes: Prediction for Mg, Ca, and Total Dissolved Carbonate Concentrations in Enceladus’ Ocean and Alkaline-Carbonate Ocean Worlds

by Keisuke Fukushi, Eigo Imai, Yasuhito Sekine, Takuma Kitajima, Baasansuren Gankhurel, Davaadorj Davaasuren and Noriko Hasebe

Minerals 2020, 10(8), 669; https://doi.org/10.3390/min10080669 - 27 Jul 2020

Cited by 16 | Viewed by 4576

Abstract

The nature of mineral precipitations in terrestrial alkaline soda lakes provides insights into the water chemistry of subsurface oceans on icy bodies in the outer solar system. Saturation analyses of terrestrial alkaline lakes have shown that the solution chemistries of lake waters are [...] Read more.

The nature of mineral precipitations in terrestrial alkaline soda lakes provides insights into the water chemistry of subsurface oceans on icy bodies in the outer solar system. Saturation analyses of terrestrial alkaline lakes have shown that the solution chemistries of lake waters are generally controlled by the presence of monohydrocalcite (MHC) and amorphous Mg-carbonate (AMC). However, direct observations of the formation of these metastable carbonates in natural alkaline lakes have been limited. This study provides evidence of in situ MHC formation in alkaline lakes, based on the water chemistry and mineralogy of suspended matter in Olgoy, Boon Tsagaan, and Orog Lakes (Valley of Gobi Lakes, Mongolia). The solution chemistries were close to saturation with respect to MHC and AMC, consistent with other alkaline lakes worldwide. Suspended matter was separated by the ultracentrifugation of lake water following freeze-drying. Our results show that MHC is the common mineral phase in the suspended matter. These observations confirm that MHC is the direct authigenic product of evaporation in alkaline lakes. The carbonate fraction in suspended matter from Olgoy Lake has a Mg/Ca ratio of 0.4, suggesting the formation of AMC in association with MHC. Based on the dissolution equilibria of AMC and MHC, we predict the Mg²⁺, Ca²⁺, and total dissolved carbonate concentrations in Enceladus’ ocean to be ~1 mmol/kg, ~10 μmol/kg, and 0.06–0.2 mol/kg, respectively, in the presence of AMC and MHC. We propose that the measurements of Mg contents in plumes will be key to constraining the total dissolved carbonate concentrations and chemical affinities of subsurface oceans on Enceladus and other alkaline-carbonate ocean worlds. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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Review

Jump to: Research

26 pages, 55759 KiB

Open AccessEditor’s ChoiceReview

Merging Perspectives on Secondary Minerals on Mars: A Review of Ancient Water-Rock Interactions in Gale Crater Inferred from Orbital and In-Situ Observations

by Rachel Y. Sheppard, Michael T. Thorpe, Abigail A. Fraeman, Valerie K. Fox and Ralph E. Milliken

Minerals 2021, 11(9), 986; https://doi.org/10.3390/min11090986 - 9 Sep 2021

Cited by 17 | Viewed by 4867

Abstract

Phyllosilicates, sulfates, and Fe oxides are the most prevalent secondary minerals detected on Mars from orbit and the surface, including in the Mars Science Laboratory Curiosity rover’s field site at Gale crater. These records of aqueous activity have been investigated in detail in [...] Read more.

Phyllosilicates, sulfates, and Fe oxides are the most prevalent secondary minerals detected on Mars from orbit and the surface, including in the Mars Science Laboratory Curiosity rover’s field site at Gale crater. These records of aqueous activity have been investigated in detail in Gale crater, where Curiosity’s X-ray diffractometer allows for direct observation and detailed characterization of mineral structure and abundance. This capability provides critical ground truthing to better understand how to interpret Martian mineralogy inferred from orbital datasets. Curiosity is about to leave behind phyllosilicate-rich strata for more sulfate-rich terrains, while the Mars 2020 Perseverance rover is in its early exploration of ancient sedimentary strata in Jezero crater. It is thus an appropriate time to review Gale crater’s mineral distribution from multiple perspectives, utilizing the range of chemical, mineralogical, and spectral measurements provided by orbital and in situ observations. This review compares orbital predictions of composition in Gale crater with higher fidelity (but more spatially restricted) in situ measurements by Curiosity, and we synthesize how this information contributes to our understanding of water-rock interaction in Gale crater. In the context of combining these disparate spatial scales, we also discuss implications for the larger understanding of martian surface evolution and the need for a wide range of data types and scales to properly reconstruct ancient geologic processes using remote methods. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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36 pages, 11257 KiB

Open AccessReview

A Review of the Phyllosilicates in Gale Crater as Detected by the CheMin Instrument on the Mars Science Laboratory, Curiosity Rover

by Valerie M. Tu, Elizabeth B. Rampe, Thomas F. Bristow, Michael T. Thorpe, Joanna V. Clark, Nicholas Castle, Abigail A. Fraeman, Lauren A. Edgar, Amy McAdam, Candice Bedford, Cherie N. Achilles, David Blake, Steve J. Chipera, Patricia I. Craig, David J. Des Marais, Gordon W. Downs, Robert T. Downs, Valerie Fox, John P. Grotzinger, Robert M. Hazen, Douglas W. Ming, Richard V. Morris, Shaunna M. Morrison, Betina Pavri, Jennifer Eigenbrode, Tanya S. Peretyazhko, Philippe C. Sarrazin, Brad Sutter, Allan H. Treiman, David T. Vaniman, Ashwin R. Vasavada, Albert S. Yen and John C. Bridges Show full author list Hide full author list

Minerals 2021, 11(8), 847; https://doi.org/10.3390/min11080847 - 6 Aug 2021

Cited by 28 | Viewed by 10610

Abstract

Curiosity, the Mars Science Laboratory (MSL) rover, landed on Mars in August 2012 to investigate the ~3.5-billion-year-old (Ga) fluvio-lacustrine sedimentary deposits of Aeolis Mons (informally known as Mount Sharp) and the surrounding plains (Aeolis Palus) in Gale crater. After nearly nine years, [...] Read more.

Curiosity, the Mars Science Laboratory (MSL) rover, landed on Mars in August 2012 to investigate the ~3.5-billion-year-old (Ga) fluvio-lacustrine sedimentary deposits of Aeolis Mons (informally known as Mount Sharp) and the surrounding plains (Aeolis Palus) in Gale crater. After nearly nine years, Curiosity has traversed over 25 km, and the Chemistry and Mineralogy (CheMin) X-ray diffraction instrument on-board Curiosity has analyzed 30 drilled rock and three scooped soil samples to date. The principal strategic goal of the mission is to assess the habitability of Mars in its ancient past. Phyllosilicates are common in ancient Martian terrains dating to ~3.5–4 Ga and were detected from orbit in some of the lower strata of Mount Sharp. Phyllosilicates on Earth are important for harboring and preserving organics. On Mars, phyllosilicates are significant for exploration as they are hypothesized to be a marker for potential habitable environments. CheMin data demonstrate that ancient fluvio-lacustrine rocks in Gale crater contain up to ~35 wt. % phyllosilicates. Phyllosilicates are key indicators of past fluid–rock interactions, and variation in the structure and composition of phyllosilicates in Gale crater suggest changes in past aqueous environments that may have been habitable to microbial life with a variety of possible energy sources. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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26 pages, 3489 KiB

Open AccessReview

A Review of Sample Analysis at Mars-Evolved Gas Analysis Laboratory Analog Work Supporting the Presence of Perchlorates and Chlorates in Gale Crater, Mars

by Joanna Clark, Brad Sutter, P. Douglas Archer, Jr., Douglas Ming, Elizabeth Rampe, Amy McAdam, Rafael Navarro-González, Jennifer Eigenbrode, Daniel Glavin, Maria-Paz Zorzano, Javier Martin-Torres, Richard Morris, Valerie Tu, S. J. Ralston and Paul Mahaffy

Minerals 2021, 11(5), 475; https://doi.org/10.3390/min11050475 - 30 Apr 2021

Cited by 19 | Viewed by 4685

Abstract

The Sample Analysis at Mars (SAM) instrument on the Curiosity rover has detected evidence of oxychlorine compounds (i.e., perchlorates and chlorates) in Gale crater, which has implications for past habitability, diagenesis, aqueous processes, interpretation of in situ organic analyses, understanding the martian chlorine [...] Read more.

The Sample Analysis at Mars (SAM) instrument on the Curiosity rover has detected evidence of oxychlorine compounds (i.e., perchlorates and chlorates) in Gale crater, which has implications for past habitability, diagenesis, aqueous processes, interpretation of in situ organic analyses, understanding the martian chlorine cycle, and hazards and resources for future human exploration. Pure oxychlorines and mixtures of oxychlorines with Mars-analog phases have been analyzed for their oxygen (O₂) and hydrogen chloride (HCl) releases on SAM laboratory analog instruments in order to constrain which phases are present in Gale crater. These studies demonstrated that oxychlorines evolve O₂ releases with peaks between ~200 and 600 °C, although the thermal decomposition temperatures and the amount of evolved O₂ decrease when iron phases are present in the sample. Mg and Fe oxychlorines decompose into oxides and release HCl between ~200 and 542 °C. Ca, Na, and K oxychlorines thermally decompose into chlorides and do not evolve HCl by themselves. However, the chlorides (original or from oxychlorine decomposition) can react with water-evolving phases (e.g., phyllosilicates) in the sample and evolve HCl within the temperature range of SAM (<~870 °C). These laboratory analog studies support that the SAM detection of oxychlorine phases is consistent with the presence of Mg, Ca, Na, and K perchlorate and/or chlorate along with possible contributions from adsorbed oxychlorines in Gale crater samples. Full article

(This article belongs to the Special Issue Expanding Views of Clays, Oxides, and Evaporites on Aquaplanets in the Solar System)

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