Surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars

Bishop, J. L.; Fairén, Alberto González; Michalski, J.; Gago-Duport, L.; Baker, Leslie L.; Velbel, M. A.; Gross, C.; Rampe, E. B.

doi:10.1038/s41550-017-0377-9

Cited by 133 publications

(142 citation statements)

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“…Despite early indications that all clay formation on Mars occurred in the Noachian (Bibring et al, ), there is increasing mineralogic evidence that there was post‐Noachian (Hesperian and maybe later) clay formation (e.g., Le Deit et al, ; Sun & Milliken, ). While conditions at Mars would suggest that precipitation (meteoric water) would only have been possible in the putatively warmer, wetter early Noachian period (e.g., Bishop et al, ; Wordsworth et al, ), groundwater could have existed through the early Hesperian (Ehlmann et al, ). Furthermore, hydrothermal conditions could have existed at depths of up to several kilometers (Michalski et al, ).…”

Section: Discussionmentioning

confidence: 99%

Anomalous Phyllosilicate‐Bearing Outcrops South of Coprates Chasma: A Study of Possible Emplacement Mechanisms

et al. 2020

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The formation of widespread phyllosilicate-bearing near-surface layers on Mars has often been attributed to pedogenesis, a process of weathering basaltic soils by continued exposure to meteoric water percolating down from the surface, which can result in layers of aluminum phyllosilicates forming over layers of iron-magnesium phyllosilicates. We present evidence of an Fe/Mg-smectite bearing layer stratigraphically above Al-phyllosilicates in three circular features to the south of Coprates Chasma, suggesting that some process other than, or in addition to, a single pedogenic sequence must have been involved. A review of several formation mechanisms shows that all models require multiple episodes of aqueous alteration. In addition, only by invoking groundwater alteration in conjunction with pedogenesis can we reconcile the stratigraphic pattern of altered material exposed by these features. Plain Language SummaryThe layered surface composition of many places on Mars is thought to have formed by top-down weathering due to rainfall or the melting of snow. We present evidence from specific locations along the southern rim of Valles Marineris that suggests that there must have been at least two distinct periods of weathering. In addition, the characteristics of these weathered materials and their relationship to craters and other landforms suggest that some of the weathering is better explained by groundwater flow, not water percolating down from the surface.

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Section: Discussionmentioning

confidence: 99%

Anomalous Phyllosilicate‐Bearing Outcrops South of Coprates Chasma: A Study of Possible Emplacement Mechanisms

et al. 2020

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“…Based on the above discussion in sections 4.1 and 4.2, we suggest that, at least in the Gale crater, MnO 2 precipitated from Mn 2+ -bearing reducing groundwater (e.g., Eh~0 V) by an interaction with high-Eh oxidants (e.g., Eh > 0. Journal of Geophysical Research: Planets acids and nitrates accumulated on the surface (Lasne et al, 2016;Smith et al, 2014), ice melting upon transient warming (e.g., Bishop et al, 2018;Kite et al, 2017;Wordsworth et al, 2017) could have provided a quantity of these oxidants to the subsurface (Fukushi et al, 2018). Given the Cl contents of the Mn enrichments (0.4-3.3 wt.%), nevertheless, the measured MnO 2 (3.7-6.0 wt.%) may not be generated solely by reactions of Mn 2+ with perchloric acids (Lanza et al, 2016).…”

Section: Potential Oxidantsmentioning

confidence: 99%

Highly Oxidizing Aqueous Environments on Early Mars Inferred From Scavenging Pattern of Trace Metals on Manganese Oxides

et al. 2019

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The Curiosity and Opportunity rovers have found depositions of manganese (Mn) (hydr)oxides within the veins of the sedimentary rocks at Gale and Endeavour craters. Since Mn is a redox sensitive element, revealing the chemical form of the Mn (hydr)oxide provides unique information on the redox state of the near‐surface/groundwater at the time of deposition. Here we report results of laboratory experiments that investigated scavenging patterns of trace metals (zinc, nickel, and chromium) on different Mn (hydr)oxides in order to constrain the chemical form of the Mn precipitates found on Mars. Our results show manganese dioxide (MnO2) scavenges zinc and nickel effectively but not for chromium. The agreement of this scavenging pattern with the observations strongly suggests that the Mn (hydr)oxides found on Mars are highly likely to be MnO2. To form MnO2, oxidizing aqueous environments are required (e.g., Eh > 0.5 V at pH ~ 8). The candidates of the oxidant include molecular oxygen, ozone, nitrates, and perchlorate acids; all of which are considered to be produced by photochemical processes. The presence of MnO2 veins in sediments suggests that such atmospheric high‐Eh oxidants may have been supplied to the subsurface, possibly through hydrological cycles activated by transient warming.

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“…; Bishop et al. ). More neutral to alkaline evaporite deposits have also been identified on Mars, including localized Cl‐salt deposits that are distributed throughout the southern highlands (Osterloo et al.…”

Section: Objective 1: Interpret the Primary Geologic Processes And Himentioning

confidence: 99%

“…Subaerial alteration probably occurred primarily during the Noachian and Hesperian on Mars and probably contributed to many of the hydrous outcrops on the surface (e.g., Bishop et al. , ; Mustard et al. ; Murchie et al.…”

Section: Objective 1: Interpret the Primary Geologic Processes And Himentioning

confidence: 99%

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The potential science and engineering value of samples delivered to Earth by Mars sample return

Beaty¹,

Grady²,

McSween³

et al. 2019

Meteorit & Planetary Scien

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Executive Summary Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the team is to re‐evaluate and update the sample‐related science and engineering objectives of a Mars Sample Return (MSR) campaign. The iMOST team has also undertaken to define the measurements and the types of samples that can best address the objectives. Seven objectives have been defined for MSR, traceable through two decades of previously published international priorities. The first two objectives are further divided into sub‐objectives. Within the main part of the report, the importance to science and/or engineering of each objective is described, critical measurements that would address the objectives are specified, and the kinds of samples that would be most likely to carry key information are identified. These seven objectives provide a framework for demonstrating how the first set of returned Martian samples would impact future Martian science and exploration. They also have implications for how analogous investigations might be conducted for samples returned by future missions from other solar system bodies, especially those that may harbor biologically relevant or sensitive material, such as Ocean Worlds (Europa, Enceladus, Titan) and others. Summary of Objectives and Sub‐Objectives for MSR Identified by iMOST This objective is divided into five sub‐objectives that would apply at different landing sites. 1.1 Characterize the essential stratigraphic, sedimentologic, and facies variations of a sequence of Martian sedimentary rocks. 1.2 Understand an ancient Martian hydrothermal system through study of its mineralization products and morphological expression. 1.3 Understand the rocks and minerals representative of a deep subsurface groundwater environment. 1.4 Understand water/rock/atmosphere interactions at the Martian surface and how they have changed with time. 1.5 Determine the petrogenesis of Martian igneous rocks in time and space. This objective has three sub‐objectives: 2.1 Assess and characterize carbon, including possible organic and pre‐biotic chemistry. 2.2 Assay for the presence of biosignatures of past life at sites that hosted habitable environments and could have preserved any biosignatures. 2.3 Assess the possibility that any life forms detected are alive, or were recently alive. Summary of iMOST Findings Several specific findings were identified during the iMOST study. While they are not explicit recommendations, we suggest that they should serve as guidelines for future decision making regarding planning of potential future MSR missions. The samples to be collected by the Mars 2020 (M‐2020) rover will be of sufficient size and quality to address and solve a wide variety of scientific questions. Samples, by definition, are a statistical representation of a larger entity...

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Surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars

Abstract: The ancient rock record for Mars has long been at odds with climate modelling. The presence of valley networks, dendritic channels and deltas on ancient terrains points towards running water Reprints and permissions information is available at www.nature.com/reprints.

Cited by 133 publications

References 92 publications

Anomalous Phyllosilicate‐Bearing Outcrops South of Coprates Chasma: A Study of Possible Emplacement Mechanisms

Anomalous Phyllosilicate‐Bearing Outcrops South of Coprates Chasma: A Study of Possible Emplacement Mechanisms

Highly Oxidizing Aqueous Environments on Early Mars Inferred From Scavenging Pattern of Trace Metals on Manganese Oxides

The potential science and engineering value of samples delivered to Earth by Mars sample return

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