HR: 14:40h
AN: P23D-05    [Abstracts]
TI: Stratigraphy and Tectonics of Arabia Terra Layered Deposits from HiRISE Imagery and Derived Meter Scale Topography
AU: * Lewis, K W
EM: klewis@gps.caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Aharonson, O
EM: oa@gps.caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Kirk, R L
EM: rkirk@usgs.gov
AF: U.S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, AZ 86001, United States
AU: McEwen, A S
EM: mcewen@pirl.lpl.arizona.edu
AF: University of Arizona Lunar and Planetary Laboratory, 1541 East University Blvd., Tucson, AZ 85721-0063, United States
AU: Okubo, C H
EM: chriso@lpl.arizona.edu
AF: University of Arizona Lunar and Planetary Laboratory, 1541 East University Blvd., Tucson, AZ 85721-0063, United States
AU: HiRISE team, a
AB: Meter scale topography from HiRISE stereo imagery allows unprecedented geometrically controlled stratigraphic studies of martian layered deposits. The widespread occurrence of light toned layered deposits within craters in western Arabia Terra was first recognized from Mars Orbiter Camera (MOC) imagery. These isolated exposures occur only within craters, although they are found over a range of hundreds of kilometers. Typically, these layered rocks exist as mounds on the crater floors which have been greatly eroded back from their original extent. In some cases, they are hundreds of meters in thickness, and composed of hundreds of parallel, meter-scale beds. The occurrence of similar layered deposits over such a large region of the planet implicates a common depositional process with relevance to planetary scale surface evolution. Using HiRISE stereo images we have derived one meter scale topographic maps of several of the western Arabia Terra layered deposits. These datasets allow a stratigraphic investigation at the scale of the observed bedding. We will discuss results of the three-dimensional mapping of these structures, focusing on tectonic and stratigraphic observations. Topographic analysis of widespread faulting within the bedrock reveals tens of meters of displacement accommodated along the larger faults, which can extend for several kilometers. Calculations of bedding orientations show large rotations up to ~30 degrees for some layered sections, indicating significant tectonic activity throughout the western Arabia region. Through precise measurement of the bedding structure the effects of deformation can be accounted for, allowing accurate reconstruction of the stratigraphic column. This process also removes the effect of the modern erosional topography, which can mask true stratigraphic thicknesses. In particular, we examine erosion resistant cliff-forming beds which occur repeatedly through some sections of the layered deposits. Our measurements allow us to accurately place these marker beds within the stratigraphic sequence, to evaluate whether they record a cyclic or stochastic depositional process. These observations will be discussed in a regional context, via comparison among various intracrater deposits for which stereo data is recently available.
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting