The Effect of High Temperatures on the Emission and VNIR Reflectance

This work is an important partof an ongoing project that includes infrared,NMR, and X-ray studies of the dehydrationand dehydroxylation of phyllosilicates andzeolites. Because most phyllosilicates found onthe surface of Mars are associated with ancientterrains [1-3], it is possible that the phyllosilicateswere repeatedly subjected to high temperaturesresulting from impact processes and continuousexposure to high temperatures is likey to lead tothe dehydration and dehydroxylation of phyl-losilicates. We hypothesize that the dehydrationand dehydroxylation of phyllosilicates subjectedto impact was a widespread process on earlyMars, and that dehydrated and dehydroxylatedphyllosilicates may be still abundant on thesurface of Mars. Zeolites were also selected as apart of this study since zeolites may be anotherimportant class of minerals that are present onthe surface of Mars in a hydrated state [4-6] andzeolites have similar chemical compositions tophyllosilicates, including a similar Si/O ratio.In previous work we performed thermo-gravimetric analysis (TGA), X-ray diffraction(XRD), attenuated total reflectance (ATR), andmid-IR and far-IR reflectance measurementson fourteen phyllosilicates, two zeolites andtheir heating products [7]. Here we continue toreport emissivity and visible and near-IR (VNIR)reflectance spectra for our samples in order to:(1) continue and improve the studies on howthe IR spectra of phyllosilicates and zeoliteschange with exposure to increasingly highertemperatures; (2) provide emissivity and VNIRreflectance data to search for the existence ofdehydrated or dehydroxylated phyllosilicatesresulting from impact events on the surface ofMars.