HR: 0800h
AN: P11A-0959    [Abstracts]
TI: Detailed Investigation of a Globally Unique, Orthopyroxene-Rich Deposit in Eos Chasma, Mars
AU: * Hamilton, V E
EM: hamilton@higp.hawaii.edu
AF: University of Hawai'i, Hawaii Institute of Geophysics and Planetology 2525 Correa Road, Honolulu, HI 96822 United States
AB: Globally unique, ALH 84001-like (orthopyroxene-bearing) materials in Eos Chasma first were identified by the author and her coworkers in a search for Martian meteorite spectral signatures in MGS TES infrared data [1]. This is the only spatially significant detection of concentrated orthopyroxene discovered on Mars to date. These materials have complete THEMIS infrared coverage (day and night) covering multiple seasons and nearly 100 percent coverage by the visible subsystem. This presentation will describe the detailed mineralogy and morphology of these materials as observed by TES and the Mars Odyssey THEMIS, as well as related data from MOC and MOLA. Because pyroxenes are relatively susceptible to aqueous weathering, the abundances of secondary minerals will be of particular interest. THEMIS visible and infrared images show that the orthopyroxene spectral features are associated with a geomorphic unit that likely is a debris flow or lobate ejecta deposit. In either case, these materials appear to superpose Eos Chasma floor units, likely were mobilized from a location within the Valles Marineris wall rock, and may represent an orthopyroxene-rich igneous unit in the lower portions of the wall rock stratigraphy. Because THEMIS images provide information about this unit in areas where there are gaps in TES data, new estimates of the area covered by this material are on the order of ~1250 km2, or at least twice the size estimated by [1]. The nighttime temperatures of these materials are consistent with coarse, sandy materials, but likely represent an average of coarser and finer particles. [1] Hamilton V. E., P. R. Christensen, H. Y. McSween Jr., and J. L. Bandfield, Meteor. Planet. Sci., 38, 871-886, 2003.
DE: 5410 Composition
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
DE: 6225 Mars
DE: 3672 Planetary mineralogy and petrology (5410)
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting