HR: 13:55h
AN: P23D-02 INVITED    [Abstracts]
TI: Recent bright gully deposits on Mars: Wet or dry flow?
AU: * Pelletier, J D
EM: jdpellet@email.arizona.edu
AF: University of Arizona, 1040 E. Fourth St, Tucson, AZ 85721, United States
AU: Kolb, K J
EM: kkolb@lpl.arizona.edu
AF: University of Arizona, 1040 E. Fourth St, Tucson, AZ 85721, United States
AU: McEwen, A S
EM: mcewen@lpl.arizona.edu
AF: University of Arizona, 1040 E. Fourth St, Tucson, AZ 85721, United States
AU: Kirk, R L
EM: rkirk@usgs.gov
AF: Astrogeology Division USGS, 2255 N. Gemini Dr, Flagstaff, AZ 86001, United States
AB: Bright gully sediments attributed to liquid water flow have been deposited on Mars within the last several years. To test the liquid-water-flow hypothesis, we constructed a high-resolution (1 m/pixel) photogrammetric Digital Elevation Model of a crater in the Centauri Montes region where a bright gully deposit formed between 2001 and 2005. We conducted 1D and 2D numerical flow modeling to test whether the deposit morphology is most consistent with liquid-water or dry-granular flow. Liquid-water-flow models that incorporate freezing can match the runout distance of the flow for certain freezing rates but fail to reconstruct the distributary lobe morphology of the distal end of the deposit. Dry-granular-flow models can match both the observed runout distance and the distal morphology, where distributary lobes are formed by viscous fingering. Wet debris flows with high sediment concentrations are also consistent with the observed morphology because their rheologies are often similar to that of dry granular flows. As such, the presence of liquid water in this flow event cannot be ruled out, but the available evidence is consistent with dry landsliding.
DE: 1824 Geomorphology: general (1625)
DE: 1827 Glaciology (0736, 0776, 1863)
DE: 5400 PLANETARY SCIENCES: SOLID SURFACE PLANETS
DE: 5419 Hydrology and fluvial processes
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting