Validated surface mineralogy from high-spectral resolution remote sensing: a review and a novel approach applied to gold exploration using AVIRIS data

Remote sensing's main limitation to date was that geological surface information lacked detail due to the broad bandwidth of the operational scanners. Imaging spectrometers now allow acquisition of image data in many contiguous spectral bands, with the aim of producing laboratory-like reflectance spectra for each pixel in the scene which can be directly compared with spectra of known materials measured in the field or laboratory to allow mineral identification on the Earth surface. The advent of satellite-based imaging spectrometer systems justifies the surge for techniques that allow the automatic preparation of validated surface mineralogy maps. We show an extension of a procedure known as cross-correlogram spectral matching to retrieve accuracy assessed surface mineralogy from Airborne Visible/InfraRed Imaging Spectrometer data (AVIRIS). The procedure is based on the spectral cross-correlation of known mineral spectra with unknown pixel spectra from AVIRIS. The validation is performed through a root-mean square calculation of expected correlograms and pixel correlograms. Results obtained in the study outlined allow an accurate delineation of zones of hydrothermal alteration in an area of active gold exploration.