New Mexico Geological Society Annual Spring Meeting — Abstracts

The University of Texas at EI Paso, 500 West University Avenue, EI Paso, Texas 79968 Evaporite minerals are the main source of several industrial and agricultural minerals important to the U.S. and world economy. Landsat ETM+ data covering the White Sands, New Mexico have been used in this study. Lake Lucero and Alkali Flat have been chosen as target sites. The study aims to 1) determine the number of endmembers that can be detected and mapped, 2) determine the spatial distribution of fractional abundances of identified endmembers assuming a linear mixing model, and 3) the ultimate objective will be the application of this initial study to future hyperspectral studies. The Minimum Noise Fraction (MNF) transform and Principal Component Analysis (PC A) were employed to determine a reduced set of noise-free spectral bands. The Pixel Purity Index (PPI) and n-D Visualization (nDV) were conducted on the reduced set of spectral bands to identify spectrally pure endmembers in the image. The following endmembers have been identified in the Alkali Flat and Lake Lucero: 1) gypsum, 2) gypsum with sparse vegetation, 3) bloedite, and 4) clay plus carbonate. Of these endmembers, only gypsum and bloedite are evaporite mineral endmembers. Mineral maps of the spatial distribution and relative abundance of evaporite minerals were performed using three different algorithms: Spectral Angle Mapper (SAM), Matched Filtering (MF), and Mixture Tuned Matched Filtering (MTMF). The results showed that gypsum has high fractional abundance in North and South Lake Lucero and Alkali Flat, whereas the fractional abundance of bloedite is low in Alkali Flat, but is higher in North Lake Lucero. The results of SAM, MF, and MTMF are validated by collecting field samples from different locations within the White Sands. A good match has been determined between results of Landsat ETM+ data, the USGS Library, and field and laboratory determined spectra. ASTER, ALI, AVIRIS, and Hyperion data are available and are in the process of being evaluated for mapping evaporite mineral endmembers. Mapping of playa evaporite minerals is of potential importance for the goal of saline soil characterization, regional groundwater hydrology and quality, mineral resource development, and climate change.