How to determine the geologic controls on the spatial distribution of hydrothermal alteration minerals in hyperspectral imagery

Airborne hyperspectral remote sensing provides detailed mineralogical information of the earth surface at high spatial resolution. In exposed terrains surface mineralogy reflects bed rock mineralogy and can be used to study geologic that were active during the formation of the various minerals currently exposed at the surface. In some ore forming processes, such as the formation of volcanic-hosted massive sulphide deposits, formation and alteration of minerals occurs at a regional scale. These mineralogical patterns can be easily detected using airborne hyperspectral imagery and aids identification of potentially mineralized locations.
Key factor in the use of hyperspectral data is the determination of the geologic significance of various minerals interpreted from the imagery and their spatial distribution. In order to determine the geologic significance we followed an integrated approach followed where here non-spectral ground data, the spectral airborne and spectral ground data were analyzed and interpreted together. Although the non-spectral (petrographic, mineralogical, geochemical, and isotopic) data provide most unambiguous information about the hydrothermal processes, the spectral data give different perspectives on these processes and only the spectral data allow evaluation of the spatial patterns using airborne methods and so provide additional information. A methodology for the use of hyperspectral remote sensing for geologic applications was developed. This methodology involves three steps:
(1) creation of maps of surface mineralogy from airborne data, (2) determination of the geologic significance of the near-infrared detectable mineralogy, and (3) evaluation of spectral patterns present in the airborne imagery.