Spectral mapping using satellite imagery can be used to outline and differentiate lithologies and mineral suites. This enables explorationists to map alteration halos associated with the circulation of hydrothermal fluids that maybe related to epithermal deposits. Two main satellite platforms are used routinely: Landsat ETM and Aster.

Mapping With Landsat

Landsat ETM is an ideal for the broad mapping and discrimination of lithological and mineral suites as it covers a wide swath of the electromagnetic spectrum.

Mapping Shear Zone hosted Au deposits in Central Asia. The image on the left outlines the main shear zones as mapped by NPA geologists. The image on the right shows clay alteration patterns. Note the coincidence of two mines (red polygons) with mapped shear zones and areas of alteration. Note also the other unexplored areas highlighted which have a coincidence of structure and alteration.

Mapping With ASTER

Whereas Landsat data cover most of the electromagnetic spectrum, Aster is ideal for the mapping and discrimination of mineral suites as its bands cover only a narrower section of the spectrum thus enabling further mineral discrimination.

Aster data used to discriminate both lithological units and mineral suites. Aster is seen as either a second stage after using Landsat or to be used in conjunction with Landsat as it can be used for greater mineralogical discrimination.

Download the pdf of this section (3.4Mb)