One million cubic kilometers of fossil ice in Valles Marineris: Relicts of a 3.5 Gy old glacial landsystem along the Martian equator

Research areas:

• Environnement, Paléo-Environnement et Bio-Indicateurs (2011 - 2016)

Year:

2014

Authors:

• Marine Gourronc
• Olivier Bourgeois
• Stéphane Pochat
• Benjamin Bultel
• Marion Massé
• Laetitia Le Deit
• Stéphane Le Mouélic
• Denis Mercier

Journal:

GEOMORPHOLOGY

Volume:

204

Pages:

235-255

Month:

JAN 1

ISSN:

0169-555X

BibTex:

@article{WOS:000328234200019, author = "Marine Gourronc and Olivier Bourgeois and St{\'e}phane Pochat and Benjamin Bultel and Marion Mass{\'e} and Laetitia Le Deit and St{\'e}phane Le Mou{\'e}lic and Denis Mercier", abstract = "Self-consistent landform assemblages suggest that Valles Marineris, the giant valley system that stretches along the Martian equator, was entirely glaciated during Late Noachian to Early Hesperian times and still contains huge volumes of fossil ice. Some of these glacial landform assemblages are illustrated here, with representative examples selected in three regions: Ius Chasma, Central Candor Chasma and the junction between Coprates Chasma and Capri Chasma. A morphological boundary separating an upper spur-and-gully morphology from a smooth basal escarpment has been spectacularly preserved along valley walls throughout Valles Marineris. The boundary winds around topographic obstacles and displays long-wavelength variations in elevation. It is associated with lateral benches, hanging valleys and truncated spurs. Comparisons with terrestrial analogs indicate that it is most reasonably interpreted as a glacial trimline. Chasma floors are covered by various kinds of terrains, including hummocky terrains, platy terrains, lateral banks, layered benches and a draping mantle. Landforms in these terrains and their spatial relationship with the interpreted trimline suggest that they correspond to various disintegration stages of an ancient glacial fill, currently protected by a superficial cover of ablation till. Altogether, these landforms and terrains compose a full glacial landsystem with wet-based glaciers that were able to flow and slide over their beds. It was most probably fed by ice accumulating at low elevations directly from the atmosphere onto valley floors and walls, with only minor contributions from tributary glaciers flowing down from higher elevations. Similar fossil glacial landsystems dating back from the early Martian history are to be expected in many other low-latitude troughs such as chasmata, chaos, valleys, impact craters and other basins. (C) 2013 Elsevier B.V. All rights reserved.", doi = "10.1016/j.geomorph.2013.08.009", extra = "PICL", issn = "0169-555X", journal = "GEOMORPHOLOGY", month = "JAN 1", pages = "235-255", title = "{O}ne million cubic kilometers of fossil ice in {V}alles {M}arineris: {R}elicts of a 3.5 {G}y old glacial landsystem along the {M}artian equator", volume = "204", year = "2014", }

Abstract:

Self-consistent landform assemblages suggest that Valles Marineris, the
giant valley system that stretches along the Martian equator, was
entirely glaciated during Late Noachian to Early Hesperian times and
still contains huge volumes of fossil ice. Some of these glacial
landform assemblages are illustrated here, with representative examples
selected in three regions: Ius Chasma, Central Candor Chasma and the
junction between Coprates Chasma and Capri Chasma. A morphological
boundary separating an upper spur-and-gully morphology from a smooth
basal escarpment has been spectacularly preserved along valley walls
throughout Valles Marineris. The boundary winds around topographic
obstacles and displays long-wavelength variations in elevation. It is
associated with lateral benches, hanging valleys and truncated spurs.
Comparisons with terrestrial analogs indicate that it is most reasonably
interpreted as a glacial trimline. Chasma floors are covered by various
kinds of terrains, including hummocky terrains, platy terrains, lateral
banks, layered benches and a draping mantle. Landforms in these terrains
and their spatial relationship with the interpreted trimline suggest
that they correspond to various disintegration stages of an ancient
glacial fill, currently protected by a superficial cover of ablation
till. Altogether, these landforms and terrains compose a full glacial
landsystem with wet-based glaciers that were able to flow and slide over
their beds. It was most probably fed by ice accumulating at low
elevations directly from the atmosphere onto valley floors and walls,
with only minor contributions from tributary glaciers flowing down from
higher elevations. Similar fossil glacial landsystems dating back from
the early Martian history are to be expected in many other low-latitude
troughs such as chasmata, chaos, valleys, impact craters and other
basins. (C) 2013 Elsevier B.V. All rights reserved.