Custom-processed, enhanced Landsat images were produced to support mineral exploration and resources mapping programs in: (1) the Marfa basin of west Texas, and (2) Puerto Rico. The objective of these projects was to map surface geologic features from the images to aid in geologic analysis of mineral potential.

Contrast-stretched false color images and high-pass filter images ranging in scale from 1:125,000 to 1:250,000 were made for both areas. Through interpretation, a variety of features (linears, curvilinears, drainage patterns, lithology, etc) were successfully mapped. A significant amount of new information was collected (e.g., 30% more linears were mapped in west Texas).

Due to the semi-arid nature of west Texas, techniques that exaggerate spectral differences of the land surface as sensed by the satellite, were used to aid in mapping rock units. A series of ratio images was made to enhance iron oxides, a potential indicator of mineralization in this area. Extensive field work and spectral radiometer studies were used to evaluate initial results and collect data to permit more effective image processing. Ratio images of the visual green and visual red spectral bands proved highly effective for mapping iron oxides.

Due to its synoptic, regional view and effectiveness for mapping a variety of surface geologic features, Landsat image processing and interpretation can provide significant new information that is especially useful in the reconnaissance stages of exploration. When used in conjunction with other data sources and geologic analysis, Landsat can improve exploration programs.

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