title: Phyllosilicates on Mars and implications for early martian climate.
abstract: The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer on board the Mars Express spacecraft. These minerals are mainly associated with Noachian outcrops, which is consistent with an early active hydrological system, sustaining the long-term contact of igneous minerals with liquid water. We infer that the two main families of hydrated alteration products detected-phyllosilicates and sulphates--result from different formation processes. These occurred during two distinct climatic episodes: an early Noachian Mars, resulting in the formation of hydrated silicates, followed by a more acidic environment, in which sulphates formed.
authors.affiliation: Institut d'Astrophysique Spatiale, Université Paris-Sud and CNRS (UMR 8617) F-91405 Orsay, France. francois.poulet@ias.fr
authors.forename: F
authors.initials: F
authors.lastname: Poulet
authors.forename: J-P
authors.initials: JP
authors.lastname: Bibring
authors.forename: J F
authors.initials: JF
authors.lastname: Mustard
authors.forename: A
authors.initials: A
authors.lastname: Gendrin
authors.forename: N
authors.initials: N
authors.lastname: Mangold
authors.forename: Y
authors.initials: Y
authors.lastname: Langevin
authors.forename: R E
authors.initials: RE
authors.lastname: Arvidson
authors.forename: B
authors.initials: B
authors.lastname: Gondet
authors.forename: C
authors.initials: C
authors.lastname: Gomez
authors.forename: M
authors.initials: M
authors.lastname: Berthé
authors.forename: S
authors.initials: S
authors.lastname: Erard
authors.forename: O
authors.initials: O
authors.lastname: Forni
authors.forename: N
authors.initials: N
authors.lastname: Manaud
authors.forename: G
authors.initials: G
authors.lastname: Poulleau
authors.forename: A
authors.initials: A
authors.lastname: Soufflot
authors.forename: M
authors.initials: M
authors.lastname: Combes
authors.forename: P
authors.initials: P
authors.lastname: Drossart
authors.forename: T
authors.initials: T
authors.lastname: Encrenaz
authors.forename: T
authors.initials: T
authors.lastname: Fouchet
authors.forename: R
authors.initials: R
authors.lastname: Melchiorri
authors.forename: G
authors.initials: G
authors.lastname: Bellucci
authors.forename: F
authors.initials: F
authors.lastname: Altieri
authors.forename: V
authors.initials: V
authors.lastname: Formisano
authors.forename: S
authors.initials: S
authors.lastname: Fonti
authors.forename: F
authors.initials: F
authors.lastname: Capaccioni
authors.forename: P
authors.initials: P
authors.lastname: Cerroni
authors.forename: A
authors.initials: A
authors.lastname: Coradini
authors.forename: O
authors.initials: O
authors.lastname: Korablev
authors.forename: V
authors.initials: V
authors.lastname: Kottsov
authors.forename: N
authors.initials: N
authors.lastname: Ignatiev
authors.forename: D
authors.initials: D
authors.lastname: Titov
authors.forename: L
authors.initials: L
authors.lastname: Zasova
authors.forename: P
authors.initials: P
authors.lastname: Pinet
authors.forename: B
authors.initials: B
authors.lastname: Schmitt
authors.forename: C
authors.initials: C
authors.lastname: Sotin
authors.forename: E
authors.initials: E
authors.lastname: Hauber
authors.forename: H
authors.initials: H
authors.lastname: Hoffmann
authors.forename: R
authors.initials: R
authors.lastname: Jaumann
authors.forename: U
authors.initials: U
authors.lastname: Keller
authors.forename: F
authors.initials: F
authors.lastname: Forget
mesh_terms: D000538:Aluminum Silicates / Q000032:analysis* / Q000737:chemistry*; D000077215:Clay; D002980:Climate; D005118:Extraterrestrial Environment / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis; D008274:Magnesium / Q000032:analysis; D018535:Mars; D013026:Space Flight; D018531:Spacecraft; D013431:Sulfates / Q000032:analysis / Q000737:chemistry; D014867:Water / Q000032:analysis / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D013431:Sulfates; D014867:Water; D007501:Iron; D008274:Magnesium; D000077215:Clay