HR: 1340h
AN: P13B-1295    [Abstracts]
TI: Bright Gully Deposits in Hale Crater and Implications for Recent Water
AU: * Kolb, K J
EM: kkolb@LPL.arizona.edu
AF: Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, United States
AU: McEwen, A S
AF: Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, United States
AU: Pelletier, J D
AF: Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, United States
AU: HiRISE Team, T
AB: Hale Crater, a late Hesperian / early Amazonian [Cabrol N.A. et al., 2001 Icarus 154] 120 km x 150 km impact crater, hosts a large number of gullies with a variety of orientations. Gully distributions and orientations have strong implications for distinguishing between gully formation theories, which frequently depend on insolation or a local aquifer. Several of the gullies exhibit bright deposits that are unmodified at the scale, 0.26 - 0.31 cm/pixel, of images acquired by the High Resolution Imaging Science Experiment (HiRISE) aboard the Mars Reconnaissance Orbiter (MRO). Two recently formed bright gully deposits (BGDs) imaged by the Mars Orbiter Camera (MOC) at other locations were initially interpreted as evidence for water on the surface in recent years [Malin M.C. et al., 2006 Science 314]. One of these BGDs was modelled by Pelletier et al. [2007 submitted] who found that, although water could not be ruled out in the formation of the studied BGD, dry flow was sufficient. HiRISE has imaged several other unmodified BGDs around Mars, most of which occur on steep slopes (26-35°) [McEwen A.S. et al., 2007 Science in press] in fresh craters. The slopes of one section of Hale Crater with BGDs are closer to 19-20°, which suggests that it would be difficult for a dry debris flow to form the BGDs. We investigate the distribution and orientations of gullies and BGDs, as well as slope profiles, in Hale Crater. We present results of modeling the BGDs using Mars Orbiter Laser Altimeter (MOLA) topography and available imagery and evaluate the likelihood that the BGDs required or included water in their formation.
DE: 1810 Debris flow and landslides
DE: 1825 Geomorphology: fluvial (1625)
DE: 1826 Geomorphology: hillslope (1625)
DE: 5419 Hydrology and fluvial processes
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting