Wide distribution and glacial origin of polar gypsum on Mars

Research areas:

• Surfaces planétaires (2011 - 2016)

Year:

2012

Authors:

• Marion Massé
• Olivier Bourgeois
• Stéphane Le Mouélic
• C. Verpoorter
• A. Spiga
• Laetitia Le Deit

Journal:

EARTH AND PLANETARY SCIENCE LETTERS

Volume:

317

Pages:

44-55

Month:

FEB 1

ISSN:

0012-821X

BibTex:

@article{WOS:000301616700005, author = "Marion Mass{\'e} and Olivier Bourgeois and St{\'e}phane Le Mou{\'e}lic and C. Verpoorter and A. Spiga and Laetitia Le Deit", abstract = "The North Polar Cap of Mars is associated with different kinds of superficial sediments, including the Circumpolar Dune Field, interior dune fields and sedimentary veneers scattered over the ice cap. In order to resolve the mineralogical composition and the regional distribution of these sediments, we processed OMEGA and CRISM hyperspectral data with an original method based on spectral derivation. We find that gypsum is present in all areas where undefined hydrated minerals had been previously detected, including superficial sedimentary veneers covering the North Polar Cap, interior dune fields and the whole Circumpolar Dune Field. Morphological and structural analyses reveal that these gypsum crystals derive directly from the interior of the ice cap. The source of superficial sedimentary veneers is the dust that was previously contained in the upper part of the ice cap, the ice-rich North Polar Layered Deposits (NPLD). This gypsum-bearing dust was released, on south-facing slopes of spiral troughs and arcuate scarps, by ice ablation controlled by katabatic winds. By the analysis of all associations of erosional scarps and dune fields over the North Polar Cap, we also demonstrate that the polar dunes are composed of sand-sized particles that were previously contained in the sediment-rich Basal Unit (BU), corresponding to the lower part of the ice cap. These particles contain gypsum and were released from the BU, by regressive ablation of ice at marginal scarps that border the North Polar Cap and by vertical ablation of ice on Olympia Planum. From a reconstruction of wind streamlines over and around the ice cap, we infer that katabatic winds descending from the polar high and rotating around the North Polar Cap control the release of these gypsum-bearing particles by ice ablation and the redistribution of these particles in the Circumpolar Dune Field. (C) 2011 Elsevier B.V. All rights reserved.", doi = "10.1016/j.epsl.2011.11.035", extra = "PICL", issn = "0012-821X", journal = "EARTH AND PLANETARY SCIENCE LETTERS", month = "FEB 1", pages = "44-55", title = "{W}ide distribution and glacial origin of polar gypsum on {M}ars", volume = "317", year = "2012", }

Abstract:

The North Polar Cap of Mars is associated with different kinds of
superficial sediments, including the Circumpolar Dune Field, interior
dune fields and sedimentary veneers scattered over the ice cap. In order
to resolve the mineralogical composition and the regional distribution
of these sediments, we processed OMEGA and CRISM hyperspectral data with
an original method based on spectral derivation. We find that gypsum is
present in all areas where undefined hydrated minerals had been
previously detected, including superficial sedimentary veneers covering
the North Polar Cap, interior dune fields and the whole Circumpolar Dune
Field. Morphological and structural analyses reveal that these gypsum
crystals derive directly from the interior of the ice cap. The source of
superficial sedimentary veneers is the dust that was previously
contained in the upper part of the ice cap, the ice-rich North Polar
Layered Deposits (NPLD). This gypsum-bearing dust was released, on
south-facing slopes of spiral troughs and arcuate scarps, by ice
ablation controlled by katabatic winds. By the analysis of all
associations of erosional scarps and dune fields over the North Polar
Cap, we also demonstrate that the polar dunes are composed of sand-sized
particles that were previously contained in the sediment-rich Basal Unit
(BU), corresponding to the lower part of the ice cap. These particles
contain gypsum and were released from the BU, by regressive ablation of
ice at marginal scarps that border the North Polar Cap and by vertical
ablation of ice on Olympia Planum. From a reconstruction of wind
streamlines over and around the ice cap, we infer that katabatic winds
descending from the polar high and rotating around the North Polar Cap
control the release of these gypsum-bearing particles by ice ablation
and the redistribution of these particles in the Circumpolar Dune Field.
(C) 2011 Elsevier B.V. All rights reserved.