Orbital Identification of Carbonate-Bearing Rocks on Mars

Ehlmann, B. L.; Mustard, John F.; Murchie, S. L.; Poulet, F.; Bishop, J. L.; Brown, Adrian; Calvin, W. M.; Clark, R. N.; Marais, David J. Des; Milliken, R. E.; Roach, L. H.; Roush, T. L.; Swayze, Gregg A.; Wray, J. J.

doi:10.1126/science.1164759

Cited by 585 publications

(603 citation statements)

References 33 publications

(10 reference statements)

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“…It now seems clear that carbonates do not exist as extensive, thick, laterally continuous bedrock units on the surface of the planet similar to those on Earth. Instead local deposits of carbonate have been discovered Ehlmann et al 2008b;Morris et al 2010), with the possibility of additional discoveries at smaller spatial scales or in mixed units excavated from the subsurface (Michalski and Niles 2010).…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments

Niles¹,

Catling²,

Berger³

et al. 2012

Quantifying the Martian Geochemical Reservoirs

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Ongoing research on martian meteorites and a new set of observations of carbonate minerals provided by an unprecedented series of robotic missions to Mars in the past 15 years help define new constraints on the history of martian climate with important cross- cutting themes including: the CO 2 budget of Mars, the role of Mg-, Fe-rich fluids on Mars, and the interplay between carbonate formation and acidity.Carbonate minerals have now been identified in a wide range of localities on Mars as well as in several martian meteorites. The martian meteorites contain carbonates in low abundances (<1 vol.%) and with a wide range of chemistries. Carbonates have also been identified by remote sensing instruments on orbiting spacecraft in several surface locations as well as in low concentrations (2-5 wt.%) in the martian dust. The Spirit rover also identified an outcrop with 16 to 34 wt.% carbonate material in the Columbia Hills of Gusev Crater that strongly resembled the composition of carbonate found in martian meteorite ALH 84001. Finally, the Phoenix lander identified concentrations of 3-6 wt.% carbonate in the soils of the northern plains.The carbonates discovered to date do not clearly indicate the past presence of a dense Noachian atmosphere, but instead suggest localized hydrothermal aqueous environments with limited water availability that existed primarily in the early to mid-Noachian followed by low levels of carbonate formation from thin films of transient water from the late Noachian to the present. The prevalence of carbonate along with evidence for active carbonate precipitation suggests that a global acidic chemistry is unlikely and a more complex relationship between acidity and carbonate formation is present.

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Section: Introductionmentioning

confidence: 99%

Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments

Niles¹,

Catling²,

Berger³

et al. 2012

Quantifying the Martian Geochemical Reservoirs

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“…They would also explain particular mixtures of clays and evaporites observed in specific localities: phyllosilicates and evaporites appear sometimes within meters or even in spatial juxtaposition of each other. This has been shown by the MER Spirit in the Columbia Hills at Gusev crater [ Wang et al ., 2006], by the MER Opportunity on the rim of Endeavour crater at Meridiani Planum [ Arvidson et al ., 2014], by the MSL Curiosity in Yellowknife Bay at Gale crater [ Vaniman et al ., 2014], and by MEX‐OMEGA and MRO‐CRISM in several places on Mars, including regional coexposures of phyllosilicates with either carbonates [ Ehlmann et al ., 2008, 2011; Carter and Poulet , 2012], sulfates [ Poulet et al ., 2005; Wiseman et al ., 2008; Hamilton et al ., 2008; Murchie et al ., 2009; Wray et al ., 2009; Milliken et al ., 2014], or chlorides [ Murchie et al ., 2009] in different locations, and even the presence of sulfate‐bearing materials underlying phyllosilicate‐bearing strata [ Wray et al ., 2010]. …”

Section: Discussionmentioning

confidence: 99%

“…Provided the existence of an alternative source of anions, mainly derived from volcanic volatiles [ Halevy and Head , 2014], it is expected that these ions would have bonded in evaporites (i.e., sulfates). However, in most localities on Mars, evaporites are commonly absent in clay‐dominated sediments [ Bandfield et al ., 2003; Bishop et al ., 2008; Ehlmann et al ., 2008; Osterloo et al ., 2008]. As a particular example, evaporites in Gale crater are the result of postdepositional fluid migration, in different late‐stage episodes of fluid flow; therefore, clays and evaporites at Gale have very different depositional histories, occurring spatially closely but with deposition times separated by hundreds of millions of years [ Nachon et al ., 2014; Rapin et al ., 2016].…”

Section: Introductionmentioning

confidence: 99%

Mineral paragenesis on Mars: The roles of reactive surface area and diffusion

et al. 2017

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Geochemical models of secondary mineral precipitation on Mars generally assume semiopen systems (open to the atmosphere but closed at the water‐sediment interface) and equilibrium conditions. However, in natural multicomponent systems, the reactive surface area of primary minerals controls the dissolution rate and affects the precipitation sequences of secondary phases, and simultaneously, the transport of dissolved species may occur through the atmosphere‐water and water‐sediment interfaces. Here we present a suite of geochemical models designed to analyze the formation of secondary minerals in basaltic sediments on Mars, evaluating the role of (i) reactive surface areas and (ii) the transport of ions through a basalt sediment column. We consider fully open conditions, both to the atmosphere and to the sediment, and a kinetic approach for mineral dissolution and precipitation. Our models consider a geochemical scenario constituted by a basin (i.e., a shallow lake) where supersaturation is generated by evaporation/cooling and the starting point is a solution in equilibrium with basaltic sediments. Our results show that cation removal by diffusion, along with the input of atmospheric volatiles and the influence of the reactive surface area of primary minerals, plays a central role in the evolution of the secondary mineral sequences formed. We conclude that precipitation of evaporites finds more restrictions in basaltic sediments of small grain size than in basaltic sediments of greater grain size.

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“…Mg-carbonates are highly undersaturated in our experiments (W $ 10 À5 ), but would likely form in special environments [Ehlmann et al, 2008]. More sulfates would form later in Mars' history as older sulfites were exposed to the oxidizing atmosphere.…”

Section: Discussionmentioning

confidence: 99%

“…To address this we conducted a series of mineral precipitation experiments from O 2 -poor solutions saturated with both calcite and hannebachite and found that inhibition of carbonate precipitation occurs at even lower values of pSO 2 :pCO 2 than predicted. This implies that even if SO 2 were not abundant enough to influence Noachian climate, it may provide an explanation for the scarcity of carbonate minerals at outcrop abundance [Christensen et al, 2001], other than in laterally restricted environments that may not represent prevailing early Martian surface conditions [Ehlmann et al, 2008]. Because this explanation for the scarcity of carbonates does not require acidic conditions, it may also account for the occurrence of early phyllosilicates [Poulet et al, 2005], which require near-neutral pH to form [Velde, 1995].…”

Section: Introductionmentioning

confidence: 99%

Sulfur dioxide inhibits calcium carbonate precipitation: Implications for early Mars and Earth

Halevy¹,

Schrag²

2009

Geophysical Research Letters

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[1] Recent studies have suggested a role for sulfur dioxide (SO 2 ) in maintaining relatively warm surface temperatures on early Mars. Here we show experimentally, that SO 2 concentrations orders of magnitude lower than those required for it to have been of climatic importance strongly affect the aqueous chemistry and the precipitated mineral assemblage. At near-neutral pH, part-per-billion concentrations of SO 2 prevent the formation of calcium carbonate in favor of hannebachite, a hydrated calcium sulfite. In the presence of iron, possible precursors to phyllosilicate minerals and iron carbonate co-precipitate with hannebachite. This provides an explanation for the existence of early Noachian phyllosilicates in the apparent dearth of outcrop-scale calcium carbonates. Oxidation of this precipitated assemblage produces sulfates, iron oxides and acidity, consistent with evidence for late Noachian -early Hesperian acid-sulfate dominated environments. For early Earth, the results allow placing an upper limit on atmospheric SO 2 concentrations for any period in which carbonates exist in the geologic record.

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Orbital Identification of Carbonate-Bearing Rocks on Mars

Cited by 585 publications

References 33 publications

Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments

Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments

Mineral paragenesis on Mars: The roles of reactive surface area and diffusion

Sulfur dioxide inhibits calcium carbonate precipitation: Implications for early Mars and Earth

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