title: Sulfates in the north polar region of Mars detected by OMEGA/Mars Express.
abstract: The Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) imaging spectrometer observed the northern circumpolar regions of Mars at a resolution of a few kilometers. An extended region at 240 degrees E, 85 degrees N, with an area of 60 kilometers by 200 kilometers, exhibits absorptions at wavelengths of 1.45, 1.75, 1.94, 2.22, 2.26, and 2.48 micrometers. These signatures can be unambiguously attributed to calcium-rich sulfates, most likely gypsum. This region corresponds to the dark longitudinal dunes of Olympia Planitia. These observations reveal that water alteration played a major role in the formation of the constituting minerals of northern circumpolar terrains.
authors.affiliation: Institut d'Astrophysique Spatiale (IAS), Bâtiment 121, 91405 Orsay Campus, France. yves.langevin@ias.u-psud.fr
authors.forename: Yves
authors.initials: Y
authors.lastname: Langevin
authors.forename: François
authors.initials: F
authors.lastname: Poulet
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bibring
authors.forename: Brigitte
authors.initials: B
authors.lastname: Gondet
mesh_terms: D001272:Atmosphere; D002133:Calcium Sulfate; D002245:Carbon Dioxide; D005118:Extraterrestrial Environment; D019015:Geologic Sediments; D018535:Mars; D008903:Minerals; D018531:Spacecraft; D019265:Spectroscopy, Near-Infrared; D013057:Spectrum Analysis; D013431:Sulfates; D013696:Temperature; D014867:Water
chemical_list: D008903:Minerals; D013431:Sulfates; D014867:Water; D002245:Carbon Dioxide; D002133:Calcium Sulfate