HR: 08:30h
AN: P11E-03    [Abstracts]
TI: Occurrence and Stratigraphy of Phyllosilicate and Hydrated Silicate Minerals on Mars from OMEGA and CRISM
AU: * Mustard, J F
EM: John_Mustard@brown.edu
AF: Dept. Geol. Sci., Brown University, Providence, RI 02912, United States
AU: Murchie, S L
AF: APL, 11100 Johns Hopkins Rd., Laurel, MD 21045, United States
AU: Pelkey, S M
AF: Dept. Geol. Sci., Brown University, Providence, RI 02912, United States
AU: Ehlmann, B L
AF: Dept. Geol. Sci., Brown University, Providence, RI 02912, United States
AU: Milliken, R E
AF: JPL-CalTech, 3800 Oak Grove Dr., Pasadena, CA 91109, United States
AU: Grant, J A
AF: CEPS, National Air and Space Museum, Washington, DC 20560, United States
AU: Bibring, J
AF: IAS, University of Paris, Orsay, 91150, France
AU: Poulet, F
AF: IAS, University of Paris, Orsay, 91150, France
AU: Bishop, J L
AF: SETI Institute, NASA/ARC, Mountain View, 94043, United States
AU: Roach, L E
AF: Dept. Geol. Sci., Brown University, Providence, RI 02912, United States
AU: Seelos, F
AF: APL, 11100 Johns Hopkins Rd., Laurel, MD 21045, United States
AU: Arvidson, R E
AF: Washington University, One Brookings Dr., St. Louis, MO 63130,
AU: Swayze, G
AU: Clark, R
AU: Wiseman, S
AF: Washington University, One Brookings Dr., St. Louis, MO 63130,
AU: Humm, D
AF: APL, 11100 Johns Hopkins Rd., Laurel, MD 21045, United States
AU: Team, C S
AB: The OMEGA investigation on the Mars Express spacecraft identified phyllosilicates across a range of martian geologic terrains, but importantly the mineral occurrences were largely confined to Noachian-aged terrains. This led to the new paradigm that that an active hydrologic system was restricted to early Mars history. The order of magnitude increase in spatial resolution of the CRISM instrument on Mars Reconnaissance Orbiter over OMEGA is used here to assess mineralogic diversity and stratigraphic relationships in several phyllosilicate regions. CRISM data show definitive evidence for diagnostic Al-OH and Fe/Mg-OH absorptions of phyllosilicate minerals, similar to those seen by OMEGA, but reveal mineralogic diversity down to the fine spatial resolution of the instrument. Al-OH phyllosilicates have been confirmed in Mawrth Vallis and are identified for the first time in the Nili Fossae region, displaying spectra consistent with kaolinite, illite and/or muscovite. A diversity of Fe/Mg-OH phyllosilicates is observed; smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. A new spectral class of mineral is found interpreted to be hydrated volcanic or impact glass. This material is found in isolated regions in the Noachian highlands. Fe/Mg phyllosilicate and hydrated glasses are found in rims, ejecta, and central peaks of craters in the southern highland Noachian cratered terrain indicating excavation of altered crust from depth. Phyllosilicate is also found in deposits clearly laid by water in Jezero, Ritchy, and Holden crater. Stratigraphic relationships in the many regions show unaltered volcanic or igneous lithologies overlying phyllosilicate-bearing rocks indicating an abrupt cessation of widespread alteration in the late Noachian. The predominance of smectite clay signatures implies moderate to low temperatures of formation (<200°C) such as might have existed in the near surface or shallow crust. The formation of phyllosilicate and hydrated glass could have been a consequence of near surface weathering or low temperature hydrothermal processes in a cooling crust
DE: 5410 Composition (1060, 3672)
DE: 5464 Remote sensing
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting