HR: 0800h
AN: P31B-0427    [Abstracts]
TI: Large Ripples and Small Dunes on the Floor of Gamboa Impact Crater on Mars
AU: Telling, J W
EM: jtelling@mail.colgate.edu
AF: Colgate University, Box X5389, 13 Oak Drive, Hamilton, NY 13346, United States
AU: * Zimbelman, J R
EM: zimbelmanj@si.edu
AF: Smithsonian Institution, CEPS/NASM MRC 315, Washington, DC 200137012, United States
AU: Williams, S H
EM: williamssh@si.edu
AF: Smithsonian Institution, Education/NASM MRC 305, Washington, DC 200137012, United States
AB: A diverse array of aeolian features are revealed in unprecedented detail in the initial release of High Resolution Imaging Science Experiment (HiRISE) data from the Primary Science Phase of the MRO mission. HiRISE image 002721-2210 was targeted on the central peak of Gamboa crater (centered on 40.8 deg. N lat., 315.7 deg. E long.), a 33-km-diameter impact feature in Acidalia Planitia. We mapped the distribution of aeolian bedforms on the floor of Gamboa crater around the central peak, measured the dimensions of the aeolian features, and categorized the features into classes that are likely related to differing processes of formation: dark broad dunes, dark linear ripples, bright linear ripples, and complex regions that are most likely combinations of two or more of the classes. Crest orientations appear to be sensitive to both local and regional relief, including some regions where the crest complexity defies any simple categorization. We interpret the dark dunes to consist of low albedo sand-sized particles much like those that have been observed during the traverses of both Mars Exploration Rovers (MERs). We also interpret the bright linear features to be granule-coated sand-cored features, again analogous to features observed by both MERs, but especially at the Opportunity site in Sinus Meridiani. Dark linear features are tentatively identified as granule ripples that have been coated by a dark (sand) layer sufficiently thick to mask the granule albedo but not thick enough to obscure the relief of the ripples. The complex regions likely also involve dark sand over bright granules, but with a very intricate crest orientation that appears to reflect both wind direction and perhaps underlying surface texture or relief. The diversity of aeolian bedforms observed within this single impact crater indicates that future HiRISE images likely will greatly expand the diversity of aeolian features observed across the planet.
DE: 1824 Geomorphology: general (1625)
DE: 5400 PLANETARY SCIENCES: SOLID SURFACE PLANETS
DE: 5470 Surface materials and properties
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting