HR: 14:55h
AN: P23D-06    [Abstracts]
TI: High-resolution structural mapping in Southwest Candor Chasma
AU: * Okubo, C H
EM: chriso@lpl.arizona.edu
AF: Lunar and Planetary Laboratory, University of Arizona 1541 East University Blvd, Tucson, AZ 85721, United States
AU: Lewis, K
EM: klewis@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: McEwen, A S
EM: mcewen@pirl.lpl.Arizona.EDU
AF: Lunar and Planetary Laboratory, University of Arizona 1541 East University Blvd, Tucson, AZ 85721, United States
AU: Kirk, R
EM: rkirk@usgs.gov
AF: U.S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, AZ 86001, United States
AU: Team, H
AF: Lunar and Planetary Laboratory, University of Arizona 1541 East University Blvd, Tucson, AZ 85721, United States
AB: We report initial results of high-resolution structural mapping of layered deposits in southwest Candor Chasma, near the contact with the surrounding wall rock. Mapping is accomplished on a digital terrain model created from stereo HiRISE imagery, with postings at every one meter. A prominent stratigraphic package, herein referred to as the ‘Slickrock Member', is present throughout the study area and consists of a characteristic sequence of massive and friable layers. Mapping of the Slickrock Member reveals both the stratigraphic continuity between faults and folds, as well as the younging direction throughout the study area. Numerous synclines, anticlines and monoclines generally trend NW-SE and have wavelengths of ca. 0.5-0.7 km. Present-day exposures through these folds indicate that at least several hundred meters of layered deposits have been eroded and removed. Normal and thrust faults are identified from the dip direction of the fault plane and sense of bedding offset. These faults generally strike NE-SW to E-W. Fault dip angles are consistent with an effective rock friction of ca. 30 degrees. Thrust faults have lengths that are 1-2 km or more, while normal faults are generally less than 0.5 km in length. Damage zones occur at several fault stopovers and bends, and fault propagation folds are also observed. Thrust fault vergence directions appear non-systematic, consistent with thick-skinned deformation. Fault planes have a ridge-like erosional morphology that rises up to 5 m above the surrounding terrain, consistent with an origin through deformation band processes. Faults crosscut the NW-SE- trending folds and these faults do not appear to be folded, indicating that brittle deformation occurred after formation of the folds. These overlapping styles of deformation, and senses of faulting, reveal multiple changes in the orientations and magnitudes of the principal stresses that drove deformation in this area. Further, large-scale normal faulting associated with opening of the chasma is not evident in the study area, suggesting that chasma formation occurred prior to deposition of the layered deposits.
UR: http://hirise.lpl.arizona.edu
DE: 5470 Surface materials and properties
DE: 5475 Tectonics (8149)
DE: 8005 Folds and folding
DE: 8010 Fractures and faults
DE: 8175 Tectonics and landscape evolution
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting