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Project Progress

Weitz et al. (2003) identified dunes, landslide materials and a blocky deposit in the floor (Fig. 1) of the Melas Chasma within Valles Marineris, as well as a large number of valleys along the southern wallrock of the chasma. Weitz et al. (2003) proposed that the blocky deposits may have been produced by subaqueous mass wasting when a lake was present or collapse and slumping of relatively wet sediments after rapid removal of a lake. In addition, Weitz et al. (2003) suggested that the valleys along the southern wallrock were evidence of relatively recent aqueous activity. UHNAI Postdoctoral fellow K. Stockstill seeks to identify the surface composition, including any unique mineralogy, of these blocky deposits using data from the Thermal Emissions Spectrometer (TES) and Thermal Emissions Imaging System (THEMIS) (Fig. 2).
Several techniques are being used to highlight spectral variation within the THEMIS emissivity data that are readily available tools in the Envi package. Specifically, a Minimum Noise Fraction (MNF) rotation technique as well as decorrelation stretches (DCS) are being used to enhance subtle spectral variation of the surface units. THEMIS and TES spectra of the different surface units can then be collected for evaluation. Figure 3 shows that MNF can be used to identify unique spectral units. Although spectral differences can be identified in the MNF image (Fig. 3), the source of the spectral variations requires further inquiry. This will involve careful inspection of TES spectra using various techniques, including linear deconvolution and spectral ratios, to search for mineralogic causes for the spectra variability.

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