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J.C. Granahan (BAE SYSTEMS)
Ionian mountains are often about 100 km across with altitudes of several kilometers (Carr et al., 1998). This fact stands in contrast to the sulfur and sulfur dioxide covered surface that dominates Io. Clow and Carr (1980) have shown that mountainous topography of this magnitude on Io can not be support by pure sulfur materials. This fact, along with high temperature volcanism, suggests that there are silicate rich materials near the surface of Io. In this study, I am analyzing Galileo Near Infrared Mapping Spectrometer (NIMS) and Solid State Imager (SSI) data of Tvashtar Montes, Tohil Mons, and the mountains by Gishbar Patera. Common to all three of these mountain areas are thermal emissions (Lopes, 2002), concentrations of sulfur dioxide, and a 3.15 micrometer non-sulfur dioxide absorption feature. The 3.15 micrometer absorption feature, first found by Smythe et al. (2002), has been detected on the plateau regions of Tvashtar Montes and the mountains by Gishbar Patera. It has also been found on a massif at Tohil Mons. Studies are now being conducted to compare the Io spectra with the libraries of silicate (particularly ultra-mafic) minerals and rocks.
References: Clow and Carr (1980) Icarus, 44, 729-733. Carr et al.(1998) Icarus, 135, 146-165. Lopes (2002) Eos Trans. AGU, 83(19), Spring Meet. Suppl., Abstract P22A-06. Smythe et al. (2002) Eos Trans. AGU, 83(19), Spring Meet. Suppl., Abstract P22A-10.
I would like to thankfully acknowledge the University of Hawaii Io co-registration subcontract which supports this research.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.