HR: 1340h
AN: OS23B-1318    [Abstracts]
TI: Repeated Cycles of Flank Growth and Collapse on Olympus Mons, Mars: Comparisons to Hawaiian Volcanoes
AU: McGovern, P J
EM: mcgovern@lpi.usra.edu
AF: Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston, TX 77058-1113 United States
AU: * Smith, J R
EM: jrsmith@hawaii.edu
AF: Hawaii Undersea Research Laboratory, University of Hawaii 1000 Pope Rd, MSB 303, Honolulu, HI 96822-2336 United States
AU: Morgan, J K
EM: morganj@rice.edu
AF: Department of Earth Science, Rice University 6100 Main St., MS-126, Houston, TX 77005-1892 United States
AU: Bulmer, M H
EM: mbulmer@jcet.umbc.edu
AF: Joint Center for Earth Systems Technology, University of Maryland Baltimore County, Baltimore, MD 21227 United States
AB: The origin of the rough-textured aureoles that surround the immense Olympus Mons volcano on Mars is controversial. We present data from the Mars Global Surveyor (MGS) mission to demonstrate that at least two of the aureole lobes are derived from the volcano's flanks in large, likely catastrophic, mass movement events, leaving behind headwalls that constitute the basal scarp. We have identified evidence linking blocky structures in the north and northeast aureole lobes to the surface of the Olympus Mons edifice, thereby favoring a mass-movement flank-failure origin for these structures. Specifically, parallel lineations on the upper surfaces of some aureole blocks resemble the leveed or channelized lava flows that are ubiquitous on the surface of the Olympus Mons edifice. Other lineations seen on aureole block surfaces may be the remnants of faults such as those seen at the margin of the Olympus Mons edifice, near the top of the basal scarp. We have determined a plausible pre-failure geometry for the edifice by matching the volume of a reconstructed edifice section to that of the North aureole lobe. A modest ($\sim$60 km) northward expansion of the current edifice is sufficient to account for the volume of the landslide that formed the North lobe, demonstrating that repeated failure events of an edifice not greatly different in size or shape from the present one are capable of generating the observed aureole deposits. The Hawaiian Islands offer structural analogs to the Olympus Mons aureole deposits (Nuuanu slide), basal scarp faults (the Pali faults) and lower edifice benches (the Hilina slump). We suggest that a basal detachment enabled by high pore fluid pressure, as inferred for Hawaiian volcanoes, allowed flank failure and aureole emplacement at Olympus Mons. Evidence for analogous flank failure processes on Mars and Earth demonstrate that repeated failures and outward spreading are universal phenomena on volcanic constructs.
DE: 8450 Planetary volcanism (5480)
DE: 8149 Planetary tectonics (5475)
DE: 5400 PLANETOLOGY: SOLID SURFACE PLANETS
DE: 5757 Remote sensing
DE: 3045 Seafloor morphology and bottom photography
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting