HR: 1340h
AN: P13B-1294    [Abstracts]
TI: The Volatile-Rich Attributes of two Deposits in a 15-km Crater on Utopia Planitia, Mars
AU: * Matias, A
EM: amatias@skidmore.edu
AF: Department of Geosciences, Skidmore College, 815 North Broadway, Saratoga Springs, NY 12866, United States
AU: Jurdy, D M
EM: donna@earth.northwestern.edu
AF: Department of Earth and Planetary Sciences, Northwestern University, 1850 Campus Drive, Evanston, IL 60208-2150, United States
AB: Recent missions to Mars with diverse instrumentation have provided a new perspective on the Martian surface. These missions allow the characterization of over 40,000 impact craters larger than 5 km in diameter, showing a diverse cratering record with some unusual morphologies. We investigate three regions in the Acidalia, Arcadia, and Utopia Planitiae covering approximately 3 % of Mars' surface. A survey of Thermal Emission Imaging System (THEMIS) images revealed 14 craters with irregular, linear to circular depressions or pits on their cavity. Importantly, only three out of these 14 craters show deposits on their floors, perhaps due to volatile-rich material. We examine the nature of two deposits on a 15-km, pitted-floor crater located within Utopia Planitia at 40.9 N, 98.3 E. A close view of the crater's floor, using THEMIS visible data, uncovers a dark deposit in addition to a lighter- colored deposit, both with possible vents. The dark deposit extends in an elliptical shape with long and short axis about 7.4 km by 4.2 km in length. On the other hand, the lighter-colored deposit looks like it is emanating southward from the vent. Importantly, this deposit displays morphology typical of fluid flows with at least three identifiable lobes and a maximum extension of 2.1 km. Textural and albedo differences between both deposits indicate their composition may not be the same. Also, superposition of the light deposit on the dark deposit makes obvious their relative timing of formation. Based on the size and scarcity of these deposits among craters of the same size, we attribute their formation to aeolian deflation exposing near-surface ground ice in two steps. Deposits coming from both vents appear relatively unaffected by wind erosion. The surface of Mars has been extensible documented as one controlled by wind erosion and deposition. Thus, both deposits appear to be relatively young, post-impact modification, with the light deposit being the youngest. The formation of these deposits in recent times suggests they are related to aeolian processes on Mars rather than a period of high obliquity.
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting