HR: 0830h
AN: C21C-0830    [PDF]
TI: Modeling the Deformation of Lobate Debris Aprons on Mars by Creep of Ice-rich Permafrost
AU: * Turtle, E P
EM: turtle@lpl.arizona.edu
AF: Planetary Sci. Inst., 1700 E. Fort Lowell Suite 106, Tucson, AZ 85719-2395 United States
AU: * Turtle, E P
EM: turtle@lpl.arizona.edu
AF: Lunar and Planetary Lab. Univ. of Arizona, 1629 E. Univ. Blvd., Tucson, AZ 85721-0092 United States
AU: Pathare, A V
EM:
AF: Planetary Sci. Inst., 1700 E. Fort Lowell Suite 106, Tucson, AZ 85719-2395 United States
AU: Crown, D A
EM:
AF: Planetary Sci. Inst., 1700 E. Fort Lowell Suite 106, Tucson, AZ 85719-2395 United States
AU: Chuang, F C
EM:
AF: Planetary Sci. Inst., 1700 E. Fort Lowell Suite 106, Tucson, AZ 85719-2395 United States
AU: Hartmann, W K
EM:
AF: Planetary Sci. Inst., 1700 E. Fort Lowell Suite 106, Tucson, AZ 85719-2395 United States
AU: Heinze, J C
EM:
AF: Lunar and Planetary Lab. Univ. of Arizona, 1629 E. Univ. Blvd., Tucson, AZ 85721-0092 United States
AU: Bueno, N F
EM:
AF: Lunar and Planetary Lab. Univ. of Arizona, 1629 E. Univ. Blvd., Tucson, AZ 85721-0092 United States
AB: Martian softened terrain and debris aprons have often been attributed to deformation of ground-ice within kilometer-thick layers of permafrost. We are using MGS MOC and MOLA data to document the structural and topographic characteristics of softened landforms and debris aprons in the Hellas and Noachis regions and comparing the observed landforms to the results of finite-element simulations of viscous creep to constrain the conditions necessary to allow such deformation on Mars. We have characterized debris aprons in a region east of the Hellas impact basin: 30$\deg$ - 50$\deg$ S, 240$\deg$ - 280$\deg$ W. No debris aprons are found around mountains at low elevation or west of 265$\deg$ W, i.e., within Hellas. We are evaluating the characteristics of mountains with and without debris aprons outside of Hellas to look for other factors that may control ground ice distribution. The only attributes that show weak correlations to the existence of debris aprons were latitude (debris aprons are more abundant to the south of our study region) and slope. We have applied finite-element analysis to investigate the deformation of debris aprons by creep of an ice-rich surface layer. Our simulations demonstrate that the final morphology is very dependent on the initial distribution of the ice-rich material and on the conditions applied at the base of the ice-rich debris. Furthermore, even under present Martian conditions, viscous creep can occur quite rapidly; on timescales of 1-10 thousand years. We are investigating the extent to which blocks of intact rock distributed within the ice-rich regolith could serve to increase the deformation timescales.
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Cryosphere [C]
MN: 2003 Fall Meeting