Geochemical Consequences of Widespread Clay Mineral Formation in Mars’ Ancient Crust

Ehlmann, B. L.; Berger, Gilles; Mangold, N.; Michalski, J. R.; Catling, David C.; Ruff, Steven W.; Chassefière, Éric; Niles, P. B.; Chevrier, V. F.; Poulet, F.

doi:10.1007/978-1-4614-7774-7_11

Cited by 2 publications

(3 citation statements)

References 184 publications

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“…If Al-rich hydrated silicates are combined (e.g., smectites, micas, and kaolins), then this group constitutes the second most abundant occurrence (~17%) after the Fe/Mg-rich smectites (~49%) [Carter et al, 2013]. There are several cases of kaolin group clays (possibly halloysite), illite and/or muscovite, zeolites, and carbonates [Mustard et al, 2008;Ehlmann et al, 2008Ehlmann et al, , 2013Murchie et al, 2009;Niles et al, 2013], all of which are consistent with the common assemblages observed in terrestrial impact structures (Table 1). Mg-Fe carbonates have been observed in Martian meteorite ALH8400l and were also recently discovered in situ on Mars by the Spirit rover [Morris et al, 2010;Niles et al, 2013].…”

Section: Hydrated Silicates In Terrestrial Impactmentioning

confidence: 99%

“…Ehlmann et al [2011] specifically classify both the crater-exposed and the less common tectonic-exposed occurrences together as "crustal clays." In general, Carter et al [2011bCarter et al [ , 2013 and Ehlmann et al [2011Ehlmann et al [ , 2013 contend that most of these occurrences are merely exposures of previously existing hydrated silicate phases. Indeed, the correlation between spectral units and geologic features, due to complexities of the impact process and Martian geologic history, does not automatically equate to an impact origin.…”

Section: Hydrated Silicate Associations With Circumbasin Terrains Andmentioning

confidence: 99%

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An impact origin for hydrated silicates on Mars: A synthesis

et al. 2013

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[1] Recent Mars-orbiting spectrometers continue to detect surface materials containing hydrated silicates, particularly clays and amorphous phases (e.g., silica glasses), concentrated within the heavily cratered Noachian highlands crust. This paper provides a review, summary, and synthesis of observations from terrestrial impact structures with current Martian data. It is suggested that numerous and frequent impacts into the volatile-rich silicate crust of Mars, through direct and indirect impact-generated mechanisms, represent a plausible hypothesis that can explain the widespread distribution of hydrated silicates in the surface and subsurface of the heavily cratered Noachian highlands crust largely independent of climate. In addition to impact-generated hydrothermal activity, devitrification, autometamorphism, and the voluminous production of impact "damaged" materials that are susceptible to alteration must be considered. When taken together, a drastically different early climate on Mars, in which water is stable at the surface for extended periods of time, cannot be ruled out; however, it is noted here that these additional impact mechanisms can operate and thereby extend the range of possible alteration settings to include climate conditions that may have been predominately colder and drier. Such a climate would not be dissimilar to the conditions of today, with the important exceptions of a higher geothermal gradient, and punctuated thermal disturbance to the cryosphere and hydrosphere from igneous activity and an exponentially higher impact flux.

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Section: Hydrated Silicates In Terrestrial Impactmentioning

confidence: 99%

Section: Hydrated Silicate Associations With Circumbasin Terrains Andmentioning

confidence: 99%

An impact origin for hydrated silicates on Mars: A synthesis

et al. 2013

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“…[2] Geomorphological and mineralogical evidence suggests that liquid water was once present at and near the surface of Mars [e.g., Baker, 2001;Bibring et al, 2006]. Widespread and numerous exposures of phyllosilicate-bearing material in the ancient southern highlands [Poulet et al, 2005;Ehlmann et al, 2013] point toward globally distributed water in the Noachian period (the Noachian is the oldest of Martian chronostratigraphic systems and ends, model dependent, sometime between~3.74 and 3.57 Gyr ago) [Werner and Tanaka, 2011]). Phyllosilicates are rare in terrains younger than the Noachian, i.e., in regions of Hesperian (ending at 3.5 to 3 Ga) and Amazonian (up to present) age, which display aqueous alteration minerals that are dominated by sulfates .…”

Section: Introductionmentioning

confidence: 99%

Asynchronous formation of Hesperian and Amazonian‐aged deltas on Mars and implications for climate

et al. 2013

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[1] Most fluvial and lacustrine landforms on Mars are thought to be old and have formed more than~3.8 Gyr ago, in the Noachian period. After a major climatic transition, surface liquid water became less abundant and finally disappeared almost completely. Recent work has shown that observational evidence for Hesperian and Amazonian aqueous processes is more common than previously recognized, but their nature is poorly understood. Moreover, it is not clear how the paleoclimate of Mars can be constrained by this activity. Here we report our investigation of a population of deltas around the ancient impact basin Chryse Planitia. To test whether the results are globally applicable, we also studied selected deltas with similar morphologies in the eastern hemisphere and found that the results are consistent. We compared the morphology of deltas, feeder channels, and receiving lakes, dated deltas by crater counting and searched for alteration minerals in hyperspectral images. The valleys and associated late-stage deltas were formed by short-lived aqueous processes, as suggested by their morphology and the general lack of associated aqueous alteration minerals. The likely source of water was neither widespread precipitation nor a regionally connected groundwater aquifer, but water mobilized locally from the cryosphere. Delta formation in our study areas occurred from the Early Hesperian to the Late Amazonian and did not require sustained periods of global climatic conditions favoring widespread precipitation. Liquid surface water has been locally present on Mars even after the Noachian, although only episodically, for transient intervals, and widely separated in space.

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Geochemical Consequences of Widespread Clay Mineral Formation in Mars’ Ancient Crust

Cited by 2 publications

References 184 publications

An impact origin for hydrated silicates on Mars: A synthesis

An impact origin for hydrated silicates on Mars: A synthesis

Asynchronous formation of Hesperian and Amazonian‐aged deltas on Mars and implications for climate

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