LITHOLOGIC MAPPING OF THE TERRACED HILLS, NORTHWESTERN PYRAMID LAKE, NEVADA, USING ASTER AND HYMAP REMOTE SENSING DATA

This research compares two different remote sensing data sets to identify and map unique mineralogical endmembers as part of an ongoing geologic and geothermal study focused on alteration within the Terraced Hills located in the northwestern Basin and Range. The Terraced Hills are composed of intercalated units of Miocene basalt, rhyolite, and dacite with localized lenses of breccias, conglomerates, and diatomites. Quaternary deposits include alluvial fans, eolian, and Lake Lahontan derived bars, shorelines, and carbonates precipitated as clay-rich sediments, shoreline tufa, and fault or hot spring controlled tufa towers. The analysis in this study involved two tiers of processing: (1) the spaceborne multispectral imager, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), to establish broadband surface cover classifications; and (2) the airborne hyperspectral imager, HyMap, to determine specific narrowband mineralogical endmembers in the scene at both higher spatial and spectral resolutions than ASTER. Processing of the data sets were done to evaluate and map the lithologies utilizing the algorithms: spectral angle mapper, matched filter, mixture tuned matched filter, and linear spectral unmixing. Spectral measurements show persistent clay, carbonate and vegetation absorption features in the 0.5-2.2 µm range. These data sets were then compared to structural and sedimentological mapping of the Terraced Hills from other workers. Together with the detailed geologic mapping and spectra analyses, results from both field and remotely sensed data are tested for validity and shown to be applicable in mineralogic and some structural mapping.