Early-stage exploration is a process of narrowing down. Remote sensing allows large licence areas to be screened quickly and at low cost before field crews are mobilised.
Multispectral and hyperspectral imagery can map hydrothermal alteration minerals such as clays, micas and iron oxides that are associated with many mineral systems. Digital elevation models and radar data reveal lineaments and structural corridors that may control mineralisation.
These layers are integrated in GIS with geology, geochemistry and geophysics to build prospectivity maps. The result is a ranked set of targets that focus mapping, sampling and drilling on the most promising ground.
Remote sensing does not replace field geology - it makes field geology more efficient. Every interpretation should be ground-truthed, and the results fed back to refine the model.