Extensive surface pedogenic alteration of the Martian Noachian crust suggested by plateau phyllosilicates around Valles Marineris

Research areas:

• Surfaces planétaires (2011 - 2016)

Year:

2012

Authors:

• Laetitia Le Deit
• Jessica Flahaut
• Cathy Quantin
• Ernst Hauber
• Olivier Bourgeois
• Joanna Gurgurewicz
• Marion Massé
• R. Jaumann

Journal:

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS

Volume:

117

Month:

MAR 21

ISSN:

2169-9097

BibTex:

@article{WOS:000301936100001, author = "Laetitia Le Deit and Jessica Flahaut and Cathy Quantin and Ernst Hauber and Olivier Bourgeois and Joanna Gurgurewicz and Marion Mass{\'e} and R. Jaumann", abstract = "Thousands of phyllosilicate-rich outcrops, mainly iron or magnesium-rich are exposed on Noachian terrains in theMartian southern highlands. We analyzed 90 CRISMobservations and more than a hundred HiRISE images located on the plateaus surrounding Valles Marineris. We mapped an extensive Al-and Fe/Mg-phyllosilicate-rich formation covering at least similar to 197,000 km(2), for which we introduce the name ``Plateau Phyllosilicates.{{\&}#039;{\&}#039;} Tens of meters in thickness, this light-toned formation crops out at various elevations on top of the Noachian units Npl(1) and Npl(2), as flat exposures on plateaus and along scarps such as valley walls, chasma walls, pit walls and impact crater rims. The Fe/Mg-phyllosilicate-rich lower member of the formation is composed of Fe/Mg-smectites (nontronite, saponite) and vermiculite. The Al-phyllosilicate-rich upper member of the formation contains Al-smectites (montmorillonite, beidellite) and locally kaolinite and/or halloysite. We suggest that the Plateau Phyllosilicates were mainly formed by pedogenesis related to the weathering of the Noachian bedrock by percolation of meteoric water or melted snow under a temperate and subarid climate during the Noachian Epoch in an alkaline to neutral environment. Kaolinite and/or halloysite may have formed in areas of more intense drainage at the surface under slightly acidic environments during the Noachian and Hesperian Epochs. Fluvial activity and deuteric alteration may have locally contributed to the genesis of phyllosilicates. This study suggests that the alteration of the Noachian basement of the plateaus surrounding Valles Marineris was widespread during the Noachian Epoch, and was still active during the Hesperian Epoch even though the water availability was limited.", doi = "10.1029/2011JE003983", extra = "PICL", issn = "2169-9097", journal = "JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS", month = "MAR 21", title = "{E}xtensive surface pedogenic alteration of the {M}artian {N}oachian crust suggested by plateau phyllosilicates around {V}alles {M}arineris", volume = "117", year = "2012", }

Abstract:

Thousands of phyllosilicate-rich outcrops, mainly iron or magnesium-rich
are exposed on Noachian terrains in theMartian southern highlands. We
analyzed 90 CRISMobservations and more than a hundred HiRISE images
located on the plateaus surrounding Valles Marineris. We mapped an
extensive Al-and Fe/Mg-phyllosilicate-rich formation covering at least
similar to 197,000 km(2), for which we introduce the name ``Plateau
Phyllosilicates.{''} Tens of meters in thickness, this light-toned
formation crops out at various elevations on top of the Noachian units
Npl(1) and Npl(2), as flat exposures on plateaus and along scarps such
as valley walls, chasma walls, pit walls and impact crater rims. The
Fe/Mg-phyllosilicate-rich lower member of the formation is composed of
Fe/Mg-smectites (nontronite, saponite) and vermiculite. The
Al-phyllosilicate-rich upper member of the formation contains
Al-smectites (montmorillonite, beidellite) and locally kaolinite and/or
halloysite. We suggest that the Plateau Phyllosilicates were mainly
formed by pedogenesis related to the weathering of the Noachian bedrock
by percolation of meteoric water or melted snow under a temperate and
subarid climate during the Noachian Epoch in an alkaline to neutral
environment. Kaolinite and/or halloysite may have formed in areas of
more intense drainage at the surface under slightly acidic environments
during the Noachian and Hesperian Epochs. Fluvial activity and deuteric
alteration may have locally contributed to the genesis of
phyllosilicates. This study suggests that the alteration of the Noachian
basement of the plateaus surrounding Valles Marineris was widespread
during the Noachian Epoch, and was still active during the Hesperian
Epoch even though the water availability was limited.