Digital analysis applied to mineral exploration at the Puerto Libertad area, Sonora, Mexico

Digital analysis of thematic mapper images and digital elevation model (DEM) of the Puerto Libertad area, emphasized a NE-E structural pattern and a less evident N-S structural trend. These structures may correspond to the distensive mechanisms of the opening of the Gulf of California. Also, semicircular structures in the area were recognized. These are associated to plutonic bodies or local volcanic centers. Exploration targets are most likely to occur in the last type of structures.;Analysis included multispectral ratios of bands 5/7 and 5/1 to enhance lithologic discrimination and alteration zones especially hydroxyl-bearing and ferric iron alterations. Principal component analysis to enhance spectral data was also performed. Images revealed new lithologic subdivisions in units previously mapped.;Analysis of DEM data and gradient operators from the first principal component image were analyzed to extract textural information.