Geophysical prospecting

In this part we do not deem it necessary to cover all the geophysical methods, but we will give some general suggestions when applying simple geophysical prospecting methods.

Analysis of a group of geophysical methods

Everyone knows that geophysics facilitates through measurements calculated on the surface, information of what is bellow the surface.

These physical parameter measurements allows us to find bodies or structures that show contrast (of density, magnetism, conductivity, etc.) when they are nearby.

It is probably less noticeable that in each method normally intervenes only one physical parameter, since geometrical factors have a lot to do with it and it’s not possible to determine anything with any method.

On table 4 we try to give a general idea of geophysical methods and mining objectives they are applicable to.

If the geologist or prospector knows what he is looking for which would mean he knows the physical properties of the mineral he is searching and the terrain he is trying to determine the structure, this table will allow him to establish what geophysical method could help him solve his problems.

Commonly used methods in deposit prospecting are:  

• spontaneous polarization (P.S.)
• magnetism
• radiometric methods (scintillometry, spectrometry)

When it comes to main descriptions, equipment, methods, etc. use the reference of “Geophysical mining”, along with se following suggestions:

1) Be careful with the equipment: they are efficient & able to work under extreme conditions, but this isn’t a reason to mistreat them, transport them without the proper precautions, cause them to breakdown, and leave them out in the open (rain, sun, etc.) or entrust them over to workers for them to measure it out themselves.
The person that is in charge of the equipment is responsible and must be conscious of its use.

2) Geophysical can be positioned:

• in the field, with the installation of topographic references
• on a map. In the case that an accurate map isn’t available, locate the measurement stations in relation with the inserted references.

3) Geophysical results must be interpreted with a geophysics help, not just because they are hard to read, but because a geologist or prospector will only analyze the results that confirm their hypothesis and discard the results that don’t.