Reconnaissance Exploration & Geological Mapping
In the reconnaissance or early exploration phase, remote sensing methods such as satellite imagery and various types of aerial photography are used as a "first-pass" to home-in on possible mineralisation sites worthy of more detailed ground appraisal. This information is commonly publicly available, but may require sophisticated computer enhancement to make the best use of it.
Some geophysical information especially magnetic intensity and radiometric data is often available as remotely sensed data - ie it has been acquired by aircraft overflying the selected area. The reconnaissance phase may involve areas of hundreds or even thousands of square kilometres.
Once the reconnaissance phase has outlined likely targets for more detailed assessment, the next step in the exploration data gathering process is normally the production of a suitable geological map. This is achieved by geologists walking over the ground surface and accurately recording the nature, location and structure of the various rocks in the target area, which may be some tens of square kilometres in area. Small hand-sized samples may be collected for further mineralogical or textural study by microscope techniques in the laboratory. Chemical analyses also yield important information to the mineral explorer.
It is normal for an area to be mapped by different geologists at different times, for a variety of purposes. As geological ideas change over time, such repetitions are advantageous to our understanding of any area.
The end product of geological mapping is a map which accurately documents rock types, alteration mineralogy, and structural data such as faults, folds, stress patterns and the dip of strata. This information is of vital importance to deduce the location of hidden ore deposits.
The activity of geological mapping has minimal environmental impact.
Reference : Mineral Exploration "The future of the Mining Industry in Western Australia" by DR M.J. DONALDSON