HR: 0800h
AN: P31B-0438    [Abstracts]
TI: Analysis of the Argyre Planitia (Mars) Sinuous Ridges Using Early MRO Images
AU: * Banks, M E
EM: mbanks@pirl.lpl.arizona.edu
AF: University of Arizona, Department of Geosciences, 1040 East 4th Street, Tucson, AZ 85721, United States
AU: Lang, N P
AF: University of Tennessee, Department of Earth and Planetary Sciences, Knoxville, TN 37996, United States
AU: McEwen, A S
AF: University of Arizona, Department of Planetary Sciences, Tucson, AZ 85721, United States
AU: Kargel, J S
AF: University of Arizona, Department of Hydrology and Water Resources, Tucson, AZ 85721, United States
AU: Baker, V R
AF: University of Arizona, Department of Hydrology and Water Resources, Tucson, AZ 85721, United States
AU: Strom, R G
AF: University of Arizona, Department of Planetary Sciences, Tucson, AZ 85721, United States
AU: Grant, J A
AF: Smithsonian Institution, Center for Earth and Planetary Studies, National Air and Space Museum, Washington, DC 20560, United States
AU: Team, H
AB: Southeastern Argyre Planitia hosts a suite of dendritic and braided sinuous ridges. Here we use imagery from the Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) camera and Context Camera (CTX) to constrain formation processes of the ridges. HiRISE images resolve large boulders, up to ~8 m in diameter, on the ridges; however, it is unclear if the boulders, particularly those that appear more angular, may be eroding out of layers of indurated material or represent transported particles. Well defined layers observed in one of the ridges are quasi-horizontal and, in general, longitudinally continuous. Frequent transitions in ridge crest morphology from sharp-crested to rounded or flat-topped are evident. In several locations, ridges also appear to lie in shallow troughs that are several kilometers in width and mantled with finer sediments. Topographic profiles across and along the three ridges imaged by HiRISE and CTX are derived from Mars Orbiter Laser Altimeter (MOLA) data and reveal that the ridges generally trend in a slope-parallel direction, but cross over low intrabasinal topographic divides. If the regional topography has remained stable, the tendency for the ridges to cross topographic highs suggests formation by pressurized flow rather than gravity driven flow (open river channels). Altogether, the Argyre ridge characteristics are consistent with sub-ice fluvial processes and most likely represent terrestrial esker-like features. Terrestrial eskers have similar morphologies and distributions and may cross topography, contain layers, and lie within troughs, often referred to as Nye channels, which form from subglacial meltwater erosion. The nature of some eroding beds within the Argyre ridges suggests a possible induration process. We present a further analysis of the characteristics of the Argyre ridges and the potential environment in which the ridges formed.
DE: 5400 PLANETARY SCIENCES: SOLID SURFACE PLANETS
DE: 5416 Glaciation
DE: 5419 Hydrology and fluvial processes
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting