Oxalate minerals on Mars?

Applin, D. M.; Izawa, M. R. M.; Cloutis, E. A.; Goltz, Douglas M.; Johnson, J. R.

doi:10.1016/j.epsl.2015.03.034

Cited by 35 publications

(36 citation statements)

References 65 publications

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“…While Benner et al's estimate did not account for processes that remove organic acids, to fall below Viking detection limits (approximately tens of ppb) over 99% of organic acids would have to be destroyed. Benner's hypothesis was further supported by more recent work that suggests solid oxalic acid is stable on the surface of Mars and may be present in reinterpreted Viking, Phoenix, and MSL data (Applin et al, 2015). Benner et al invokes Fenton chemistry that requires exposure to UV radiation (3-100 eV), which can only penetrate the first several millimeters of Martian soil (Cockell & Raven, 2004).…”

Section: Alteration Of Organic Materials By Ionizing Radiationmentioning

confidence: 93%

Radiolysis of Macromolecular Organic Material in Mars‐Relevant Mineral Matrices

2019

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The fate of organic material on Mars after deposition is crucial to interpreting the source of these molecules. Previous work has addressed how various organic compounds at millimeter depths in sediments respond to ultraviolet radiation. In contrast, this study addressed how high‐energy particle radiation (200‐MeV protons, simulating the effect of galactic cosmic rays and solar wind at depths of <4–5 cm) influences organic macromolecules in sediments. Specifically, we report the generation of organic‐acid radiolysis products after exposure to radiation doses equivalent to geological time scales (1–7 Myr). We found that formate and oxalate were produced from a variety of organic starting materials and mineral matrices. Unlike ultraviolet‐driven reactions that can invoke Fenton chemistry to produce organic acids, our work suggests that irradiation of semiconductor surfaces, such as TiO2 or possible clay minerals found on Mars, forms oxygen and hydroxyl radical species, which can break down macromolecules into organic acids. We also investigated the metastability of benzoate in multiple mineral matrices. Benzoate was added to samples prior to irradiation and persisted up to 500 kGys of exposure. Our findings suggest that organic acids are likely a major component of organic material buried at depth on Mars.

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Section: Alteration Of Organic Materials By Ionizing Radiationmentioning

confidence: 93%

Radiolysis of Macromolecular Organic Material in Mars‐Relevant Mineral Matrices

2019

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“…Reanalyses of a Martian mudstone by X‐ray diffraction (XRD) by the CheMin instrument on the Mars Science Laboratory (MSL) Curiosity rover by Applin et al . [] showed that the XRD measurements are consistent with the presence of low levels of refractory Ca, Fe, or Mg oxalates. The possible wide distribution of oxalates on the Martian surface suggests that oxalate formation is a widespread process on Mars that has the potential to affect the global cycling of carbon and the geochemistry of organic matter.…”

Section: Introductionmentioning

confidence: 80%

“…In addition, the presence of persistent lichen communities in different marginal areas (Figures S5–S7) provides a plausible nearby biological source of oxalate [ Chen et al ., ]. Due to its extreme resistance to degradation [e.g., Applin et al ., ], oxalate minerals should be easily transferred to the sedimentary deposits of the basin. If the link between preserved oxalates and biological activity is correct, then the oxalate preserved in the detrital and chemical sediments of the Salar Grade provides a record of biological activity during the formation and evolution of the basin spanning several million years [ Sáez et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…The lower detrital unit hosting the crystalline Ca‐oxalates likely formed under conditions of extremely low water availability [ Russ et al ., , ], during which sedimentation would have been driven by very sporadic erosive episodes associated with active tectonics. Conversely, the presence of oxalate in the rich upper halite supports the presence of a transient water mass hosting microbial activity that produced organic compounds that were then exposed to photochemical oxidation to form oxalate [ Benner et al ., ; Applin et al ., ]. This would increase the concentration of oxalate anions and the precipitation of oxalate compounds inside the halite salt body under strong evaporation.…”

Section: Discussionmentioning

confidence: 99%

“…The possible occurrence of oxalates on Mars has been recently reported in different Mars regions by Applin et al . [], who reinterpreted the samples analyzed by different pyrolysis‐based instruments aboard Viking, Phoenix, and Curiosity, i.e., the pyrolysis gas chromatograph–mass spectrometer, the Thermal and Evolved Gas Analyzer, and the Sample Analysis at Mars, respectively [ Biemann et al ., ; Boynton et al ., ; Mahaffy et al ., ; Ming et al ., ]. Reanalyses of a Martian mudstone by X‐ray diffraction (XRD) by the CheMin instrument on the Mars Science Laboratory (MSL) Curiosity rover by Applin et al .…”

Section: Introductionmentioning

confidence: 99%

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Oxalate formation under the hyperarid conditions of the Atacama desert as a mineral marker to provide clues to the source of organic carbon on Mars

et al. 2016

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In this study, we report the detection and characterization of the organic minerals weddellite (CaC2O4 · 2H2O) and whewellite (CaC2O4 · H2O) in the hyperarid, Mars‐like conditions of the Salar Grande, Atacama desert, Chile. Weddellite and whewellite are commonly of biological origin on Earth and have great potential for preserving records of carbon geochemistry and possible biological activity on Mars if they are present there. Weddellite and whewellite have been found as secondary minerals occurring inside the lower detrital unit that fills the Salar Grande basin. The extremely low solubility of most oxalate minerals inhibits detection of oxalate by ion chromatography (IC). Crystalline oxalates, including weddellite and whewellite, were detected by X‐ray diffraction (XRD). The association of weddellite with surface biota and its presence among subsurface detrital materials suggest the potential of a biological origin for Salar Grande weddellite and whewellite. In this regard, biological activity is uniquely capable of concentrating oxalates at levels detectable by XRD. The complementary detection of oxalate‐bearing phases through IC in the upper halite‐rich unit suggests the presence of a soluble oxalate phase in the basin that is not detected by XRD. The formation, transport, and concentration of oxalate in the Salar Grande may provide a geochemical analogue for oxalate‐bearing minerals recently suggested to exist on Mars.

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Orbital evidence for more widespread carbonate‐bearing rocks on Mars

et al. 2016

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Carbonates are key minerals for understanding ancient Martian environments because they are indicators of potentially habitable, neutral-to-alkaline water and may be an important reservoir for paleoatmospheric CO 2 . Previous remote sensing studies have identified mostly Mg-rich carbonates, both in Martian dust and in a Late Noachian rock unit circumferential to the Isidis basin. Here we report evidence for older Fe-and/or Ca-rich carbonates exposed from the subsurface by impact craters and troughs. These carbonates are found in and around the Huygens basin northwest of Hellas, in western Noachis Terra between the Argyre basin and Valles Marineris, and in other isolated locations spread widely across the planet. In all cases they cooccur with or near phyllosilicates, and in Huygens basin specifically they occupy layered rocks exhumed from up to~5 km depth. We discuss factors that might explain their observed regional distribution, arguments for why carbonates may be even more widespread in Noachian materials than presently appreciated and what could be gained by targeting these carbonates for further study with future orbital or landed missions to Mars.

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Oxalate minerals on Mars?

Cited by 35 publications

References 65 publications

Radiolysis of Macromolecular Organic Material in Mars‐Relevant Mineral Matrices

Radiolysis of Macromolecular Organic Material in Mars‐Relevant Mineral Matrices

Oxalate formation under the hyperarid conditions of the Atacama desert as a mineral marker to provide clues to the source of organic carbon on Mars

Orbital evidence for more widespread carbonate‐bearing rocks on Mars

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