Image processing of aeromagnetic data and integration with Landsat images for improved structural interpretation

Abstract

Digital image processing of aeromagnetic data from three mineral prospects significantly improved the existing structural interpretations that were made from contour maps of the aeromagnetic data. Useful image‐processing techniques include (1) presentation as small‐scale, gray‐level images, (2) local contrast enhancement, (3) artificial illumination, and (4) directional filtering. Digital processing also enables direct comparison between Landsat data and aeromagnetic data. Interpretations were improved by the study of the integrated data sets. Images of aeromagnetic data from one prospect in a Precambrian granite‐greenstone terrane show major folds and faults that were not previously recognized from contour maps of the aeromagnetic data. A Landsat Multispectral Scanner (MSS) image shows the subtle surface expression of two folds. The newly identified structures point to additional prospective ground in the search for volcanogenic massive sulfide deposits in the area. Aeromagnetic data from a second prospect are complicated by a young, north‐south striking, strongly magnetic, diabase dike swarm. Directional filtering and artificial illumination of the aeromagnetic data effectively remove the response of the dikes and enhance the earlier structural and lithologic features. The combined interpretation of illuminated aeromagnetic and registered Landsat Thematic Mapper (TM) images for a third prospect added several significant faults that were previously unrecognized from separate interpretations of contour maps of aeromagnetic data and the Landsat image.