Martian polar and circum-polar sulfate-bearing deposits: Sublimation tills derived from the North Polar Cap

Research areas:

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

Year:

2010

Authors:

• Marion Massé
• Olivier Bourgeois
• Stéphane Le Mouélic
• C. Verpoorter
• Laetitia Le Deit
• J. P. Bibring

Journal:

ICARUS

Volume:

209

Number:

2

Pages:

434-451

Month:

October

ISSN:

0019-1035

BibTex:

@article{WOS:000282199000013, author = "Marion Mass{\'e} and Olivier Bourgeois and St{\'e}phane Le Mou{\'e}lic and C. Verpoorter and Laetitia Le Deit and J. P. Bibring", abstract = "Previous spectroscopic studies have shown the presence of hydrated minerals in various kinds of sedimentary accumulations covering and encircling the martian North Polar Cap. More specifically, gypsum, a hydrated calcium sulfate, has been detected on Olympia Planum, a restricted part of the Circum-Polar Dune Field. To further constrain the geographical distribution and the process of formation and accumulation of these hydrated minerals, we performed an integrated morphological, structural and compositional analysis of a key area where hydrated minerals were detected and where the main polar landforms are present. By the development of a spectral processing method based on spectral derivation and by the acquisition of laboratory spectra of gypsum-ice mixtures we find that gypsum-bearing sediment is not restricted to the Olympia Planum dunes but is also present in all kinds of superficial sediment covering the surface of the North Polar Cap and the Circum-Polar Dune Field. Spectral signatures consistent with perchlorates are also detected on these deposits. The interpretation of landforms reveals that this gypsum-bearing sediment was released from the ice cap by sublimation. We thus infer that gypsum crystals that are now present in the Circum-Polar Dune Field derive from the interior of the North Polar Cap. Gypsum crystals that were initially trapped in the ice cap have been released by sublimation of the ice and have accumulated in the form of ablation tills at the surface of the ice cap. These gypsum-bearing sublimation tills are reworked by winds and are transported towards the Circum-Polar Dune Field. Comparison with sulfates found in terrestrial glaciers suggests that gypsum crystals in the martian North Polar Cap have formed by weathering of dust particles, either in the atmosphere prior to their deposition during the formation of the ice cap, and/or in the ice cap after their deposition. (C) 2010 Elsevier Inc. All rights reserved.", doi = "10.1016/j.icarus.2010.04.017", extra = "PICL", issn = "0019-1035", journal = "ICARUS", month = "OCT", number = "2", pages = "434-451", title = "{M}artian polar and circum-polar sulfate-bearing deposits: {S}ublimation tills derived from the {N}orth {P}olar {C}ap", volume = "209", year = "2010", }

Abstract:

Previous spectroscopic studies have shown the presence of hydrated
minerals in various kinds of sedimentary accumulations covering and
encircling the martian North Polar Cap. More specifically, gypsum, a
hydrated calcium sulfate, has been detected on Olympia Planum, a
restricted part of the Circum-Polar Dune Field. To further constrain the
geographical distribution and the process of formation and accumulation
of these hydrated minerals, we performed an integrated morphological,
structural and compositional analysis of a key area where hydrated
minerals were detected and where the main polar landforms are present.
By the development of a spectral processing method based on spectral
derivation and by the acquisition of laboratory spectra of gypsum-ice
mixtures we find that gypsum-bearing sediment is not restricted to the
Olympia Planum dunes but is also present in all kinds of superficial
sediment covering the surface of the North Polar Cap and the
Circum-Polar Dune Field. Spectral signatures consistent with
perchlorates are also detected on these deposits. The interpretation of
landforms reveals that this gypsum-bearing sediment was released from
the ice cap by sublimation. We thus infer that gypsum crystals that are
now present in the Circum-Polar Dune Field derive from the interior of
the North Polar Cap. Gypsum crystals that were initially trapped in the
ice cap have been released by sublimation of the ice and have
accumulated in the form of ablation tills at the surface of the ice cap.
These gypsum-bearing sublimation tills are reworked by winds and are
transported towards the Circum-Polar Dune Field. Comparison with
sulfates found in terrestrial glaciers suggests that gypsum crystals in
the martian North Polar Cap have formed by weathering of dust particles,
either in the atmosphere prior to their deposition during the formation
of the ice cap, and/or in the ice cap after their deposition. (C) 2010
Elsevier Inc. All rights reserved.