HR: 16:25h
AN: P24A-03    [Abstracts]
TI: HiRISE Observations of Martian Mid-Latitude Fractured Mounds
AU: * Dundas, C M
EM: colind@lpl.arizona.edu
AF: University of Arizona Department of Planetary Sciences, 1629 E. University Blvd., Tucson, AZ 85721, United States
AU: Mellon, M T
EM: Mellon@lasp.colorado.edu
AF: University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO 80309, United States
AU: McEwen, A S
EM: mcewen@pirl.lpl.arizona.edu
AF: University of Arizona Department of Planetary Sciences, 1629 E. University Blvd., Tucson, AZ 85721, United States
AU: Lefort, A
EM: alexandra.lefort@space.unibe.ch
AF: Universitat Bern, Physikalisches Institut, Bern, CH-3012, Switzerland
AU: Keszthelyi, L P
EM: laz@usgs.gov
AF: U.S. Geological Survey Astrogeology Team, 2255 N. Gemini Dr., Flagstaff, AZ 86001, United States
AU: Thomas, N
EM: nicolas.thomas@space.unibe.ch
AF: Universitat Bern, Physikalisches Institut, Bern, CH-3012, Switzerland
AU: Team, H
EM: N/A
AB: The High Resolution Imaging Science Experiment (HiRISE) camera has now returned thousands of images of the Martian surface with pixel scale as small as 26 cm/pixel. These have revealed fractured mounds up to several hundred meters in diameter, bearing some morphological resemblance to terrestrial pingos (ice-cored hills formed by freezing groundwater). Pingos on Mars would be valuable indicators of ground ice and have been suggested at a number of sites, but in several cases reexamination has supported different origins. Some differences do exist between the fractured mounds and terrestrial pingos. In several instances, the mounds have roughly trapezoidal topographic profiles with flat, fractured summits. Other morphologies are also seen; we report on the range of morphologies observed so far by HiRISE and similarities and differences with pingos on Earth. The fractured mounds observed to date generally appear in the mid-latitudes, at a range of longitudes. Mars Orbiter Camera (MOC) images of flat-topped mounds in Utopia Planitia (including some previously proposed pingos) show a similar latitudinal dependence, generally occurring between 35-45° N. This supports a ground- ice related origin, particularly since the latitude range is close to the peak-abundance latitude of some other features likely related to water or ice, such as gullies. It is still uncertain whether the formation mechanism of the fractured mounds is the same as terrestrial pingos in detail. We discuss the distribution, properties and settings of fractured mounds observed planet-wide by HiRISE.
DE: 0702 Permafrost (0475)
DE: 5422 Ices
DE: 5470 Surface materials and properties
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting