HR: 0830h
AN: P21B-0050    [PDF]
TI: Thermal Emission Spectrometer Derived Chemical Abundances of Low-Albedo Surfaces on Mars
AU: * Wyatt, M B
EM: michael.wyatt@asu.edu
AF: Department of Geological Sciences, Arizona State University, Tempe, AZ 85287-6305 United States
AU: Bandfield, J L
EM: joshband@asu.edu
AF: Department of Geological Sciences, Arizona State University, Tempe, AZ 85287-6305 United States
AU: McSween, H Y
EM: mcsween@utk.edu
AF: Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996-1410 United States
AU: Christensen, P R
EM: phil.christensen@asu.edu
AF: Department of Geological Sciences, Arizona State University, Tempe, AZ 85287-6305 United States
AB: The mineralogical and chemical properties of the dust, soil, and rocks that comprise the martian regolith are a reflection of the igneous and sedimentary processes that create and modify these materials. TES derived mineral abundances have been used to constrain the bulk composition of the martian surface and provide insight to the degree of differentiation of the martian crust and mantle and the nature of surface-atmosphere interactions. TES is primarily a mineralogical tool, but it can also provide a means of estimating chemistry. Bulk rock geochemistry can be accurately calculated from deconvolved modal mineralogies by combining the compositions (wt.% oxides) of the spectral end-members in proportion to their relative modeled abundances. Derived chemical abundances from thermal emission spectra are thus a recasting of rock compositions into a form which complements modeled mineral abundances. In studies of terrestrial volcanic rocks at both laboratory (2 cm$^{-1}$) and TES (10 cm$^{-1}$) spectral samplings, the one-$\sigma$ standard deviations of the absolute differences between measured and modeled major oxide abundances (SiO$_{2}$, Na$_{2}$O, K$_{2}$O, CaO, MgO, FeO, Al$_{2}$O$_{3}$) range from 0.4 to 2.6 wt %. Derived chemistries have been used to accurately classify volcanic compositions and demonstrate the feasibility of using similar techniques for the interpretation of terrestrial laboratory samples and TES-resolution data. In this study, we report initial global major oxide abundance maps (4 pixels/degree or 15 km/pixel) of low-albedo materials to be used with existing global mineral abundance maps for accurately classifying martian surface compositions. Volcanic rocks are commonly assigned petrologic names by their chemical compositions because their modal mineralogies, even when quantified, are not always diagnostic. TES derived major oxide abundance maps can also serve for comparison to 2001 Mars Odyssey Gamma Ray Spectrometer derived element abundance maps (.1 pixels/degree or 600 km/pixel). Examining both mineralogical and chemical relationships over spatial and temporal scales will provide additional insight to better understand the relative roles of igneous and sedimentary processes on Mars.
DE: 5410 Composition
DE: 5464 Remote sensing
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting