HR: 14:40h
AN: P13C-05 INVITED     [Abstracts]
TI: OMEGA surface mineralogical mapping, and its derived early Mars evolution
AU: * Jean-Pierre, B
EM: bibring@ias.u-psud.fr
AF: Institut d'Astrophysique Spatiale, Batiment 121, Orsay, 91405 France
AU: OMEGA team, a
P13C-05 AF: Institut d'Astrophysique Spatiale, Batiment 121, Orsay, 91405 France
AB: Over the one Martian year of Mars Express nominal mission, OMEGA mapped almost the entire Martian surface at a few kilometer-scale resolution, and a number of spots at better than 400m resolution amounting to some 5 percents of the surface. The spectrum of each resolved pixel is acquired from 0.35 to 5.1 micrometers, which enables to assess the composition from diagnostic signatures for the major atmospheric and surface constituents. In particular, OMEGA has identified and mapped Fe-bearing mafic minerals (pyroxene and olivine), hydrated silicates and other hydrated minerals (sulfates), non hydrated oxides, so as to infer a long-term evolution sequence, with a special emphasis on early (Noachian to Hesperian) steps. One of the major outcomes is the evolution of the alteration products, started with the formation of massive structures of phyllosilicates, followed by that of sulfates, then non hydrated oxides. We will present the data out of which this sequence is proposed, and discuss it in terms of water-driven processes, suggesting that the era during which surface liquid water was abundant on extended periods is restricted to the early hundreds of million years of the planet. We will propose processes to account for the diversity of alteration products and structures characterized so far.
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: Fall Meeting 2005