HR: 0800h
AN: P31C-0551    [Abstracts]
TI: Which processes form the volcanic sands on Mars?
AU: Grégoire, M
EM: gregoire@dtp.obs-mip.fr
AF: Observatoire Midi-Pyrénées Laboratoire Dynamique Terrestre et Planétaire, UMR5562 CNRS et Université Paul Sabatier Toulouse III, 14, Avenue Edouard Belin, Toulouse, 31400, France
AU: * Baratoux, D
EM: baratoux@dtp.obs-mip.fr
AF: Observatoire Midi-Pyrénées Laboratoire Dynamique Terrestre et Planétaire, UMR5562 CNRS et Université Paul Sabatier Toulouse III, 14, Avenue Edouard Belin, Toulouse, 31400, France
AU: Mangold, N
EM: mangold@u-psud.fr
AF: Interactions et Dynamique des Environnements de Surface, UMR 8148 CRNS et Université Paris Sud, Centre Universitaire d'Orsay, Orsay, 91405, France
AU: Arnalds, O
EM: ola@rala.is
AF: Agricultural University of Iceland, Hvanneyri, Bogarnes, 311, Iceland
AU: Platvoet, B
EM: platvoet@geol.u-psud.fr
AF: Interactions et Dynamique des Environnements de Surface, UMR 8148 CRNS et Université Paris Sud, Centre Universitaire d'Orsay, Orsay, 91405, France
AU: Bardinzeff, J
EM: jacques-marie.bardintzeff@u-psud.fr
AF: Interactions et Dynamique des Environnements de Surface, UMR 8148 CRNS et Université Paris Sud, Centre Universitaire d'Orsay, Orsay, 91405, France
AU: Pinet, P
EM: pinet@dtp.obs-mip.fr
AF: Observatoire Midi-Pyrénées Laboratoire Dynamique Terrestre et Planétaire, UMR5562 CNRS et Université Paul Sabatier Toulouse III, 14, Avenue Edouard Belin, Toulouse, 31400, France
AB: Volcanic sands are common at the surface of Mars. They are usually of basaltic composition. Occurrence of sands, mostly recognized as dark dune fields include numerous impact craters in the southern hemisphere [1], several volcanic provinces such as Cerberus and Syrtis Major[2], several impact craters in the northern hemisphere, the large basins (Hellas and Argyre), Valles Marineris, and the poles [3]. In most cases, the sands are of basaltic composition [2,4], at the exception of the polar dunes which are made of sulfates [3]. It is interesting to note that dunes have been found on the Hesperian volcanic plateau of Systis Major, while they are not reported on Tyrrhena Terra, a volcanic province similar in age and morphology to Syrtis. It seems thus that the formation of sand from volcanic material is not systematic and thus requires particular conditions. These different situations which will be presented raise the following questions. When did these volcanic sands form in the Martian history? Did they result from a long-standing and slow process operating in the present cold conditions or did they result from several episodes associated for instant to climate changes? We review several mechanisms which could account for the formation of volcanic sand on Mars from the volcanic material. In particular, we focus on the role of cold-climate processes from an analysis of terrestrial analogs in Iceland. In this case, the advance and retreat of glaciers over a recent erupted shield volcano associated with the strong catabatic winds have resulted in the rapid formation (less than few thousands years) of large volumes of sands. [1] Fenton, L. K. (2005), Potential sand sources for the dune fields in Noachis Terra, Mars, J. Geophys. Res. 110, E11004, doi :10.1029/2005JE002436. [2] Vaucher et. al, in revision for Icarus [3] Langevin et. al, (2005), Science, 307, 1584-1586 [4] Poulet F., Mangold N. and Erard S. (2003), Astron. & Astrophys. 412, L19-L23.
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1886 Weathering (0790, 1625)
DE: 5415 Erosion and weathering
DE: 5419 Hydrology and fluvial processes
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting