HR: 1330h
AN: P42A-0422    [PDF]
TI: Debris Aprons in the Tempe/Mareotis Region of Mars
AU: * Chuang, F C
EM: chuang@psi.edu
AF: Planetary Science Institute, 1700 E Fort Lowell Road, Suite 106, Tucson, AZ 85719
AU: Crown, D A
AF: Planetary Science Institute, 1700 E Fort Lowell Road, Suite 106, Tucson, AZ 85719
AB: Martian debris aprons are considered to be geomorphic indicators of ground ice, and thus are important in understanding the climate and volatile inventory on Mars. Their presence suggests storage of ice in the Martian regolith, either currently or in the recent geologic past. Recent studies of aprons have focused on the eastern Hellas and Deuteronilus/Protonilus Mensae regions of Mars, which have some of the highest apron concentrations on the planet. However, there are several other locales that have significant populations of aprons. We have initiated a new study of aprons located along the northern lowlands-southern cratered highlands boundary in the Tempe/Mareotis Fossae region (43-55N, 274-294E). Seventy-three apron complexes have been identified in Viking images, and we further document their surface textures, morphometric properties, and topographic characteristics using MOC narrow-angle images, MOLA PEDR profile data, and THEMIS daytime (VIS and IR) and nighttime (IR) images. Debris apron complexes generally consist of one or more lobate deposits that surround individual massifs or small knobs, but have also been observed along the bases of escarpments and inner crater walls. The Tempe/Mareotis aprons have a similar planimetric morphology to those observed elsewhere on Mars. A series of distinctive textures are observed on the surfaces of Tempe/Mareotis aprons that can be attributed to differences in preservation state. Smooth, pitted, ridge and valley, and knobby textures characterize upper apron materials, which often appear to be mantled by a fine-grained deposit. Smooth and ridged erosional textures appear to form in low-lying areas where upper apron material has been removed. The degradation of upper apron material generally begins with a smooth, mantled surface that is gradually removed by sublimation, melting, and/or aeolian activity, which leaves behind a hummocky surface texture composed of knobs, ridges, or both. Further degradation produces subdued and smooth erosional textures in some areas, which may have contained greater abundances of ice. MOLA profiles across many of the Tempe/Mareotis aprons show a well-defined convex-upward shape similar to those observed in the eastern Hellas and Deuteronilus/Protonilus Mensae regions. However, not all apron profiles have such shapes, and many have a linear slope or a slightly convex-upwards shape. The combined textural and morphometric variability of Tempe/Mareotis aprons suggest potential differences in emplacement style or ice content in addition to preservation state. Our continued study of Tempe/Mareotis aprons will also assess the influence of geology and geologic history relative to aprons observed in other regions of Mars.
DE: 5415 Erosion and weathering
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting