HR: 10:50h
AN: P32A-03    [Abstracts]
TI: HiRISE Observations of Layered Deposits In and Around Valles Marineris
AU: * Weitz, C M
EM: weitz@psi.edu
AF: Planetary Science Institute, 1700 E. Fort Lowell Suite 106, Tucson, AZ 85719, United States
AU: McEwen, A
EM: mcewen@pirl.lpl.arizona.edu
AF: University of Arizona, Sonett Space Science Building 1541 E. University Blvd, Tucson, AZ 85721, United States
AU: Team, H S
AB: The HiRISE camera on the Mars Reconnaissance Orbiter is providing spectacular images of Mars in color and at approximately 30-60 cm/pixel resolution. Stereo images produced by taking two images at different roll angles are also valuable for viewing topography and stratigraphy. We have used the HiRISE data to examine the light- toned layered deposits (LTLD), both inside Valles Marineris and on the plains outside of the canyons. The high- resolution images show extensive layering with variable lithologies. Inside of Valles Marineris, massive blocky lithologies can be interbedded with meter-scale layered units, suggesting either different depositional environments or post-deposition modification of local areas. Folding is evident in West Candor Chasma near the contact with the wallrock, indicating post-deposition disruption, perhaps associated with further extension in Valles Marineris. Stereo images reveal tilting of layered beds in several locations. Fractures, joints, and faults in the LTLD are also commonly seen in several locations. The LTLD outside of Valles Marineris are concentrated near Ius Chasma, Melas Chasma, and Juventae Chasma. These layered deposits have darker units interbedded with light-toned deposits, and other color variations are also visible. While the ages of the LTLD inside Valles Marineris relative to the formation of the canyons is still under debate, those on the plains are stratigraphically above the Hesperian lavas and consequently represent a relatively younger period of LTLD emplacement. Even at the highest resolution, there is a paucity of impact craters on the LTLD, suggesting the units are friable in nature, although rapid burial beneath dark mantle deposits and formerly overlying units may also explain why there are so few craters. Why LTLD are in specific, but not all, locations within and adjacent to Valles Marineris is still being debated.
DE: 5464 Remote sensing
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Joint Assembly