Geophysics is a field of applied science that measures environmental properties such as the local magnetic field, or gravity contrast, or apparent resistivity, and uses these properties to determine the nature of the local geographic phenomena – be it to uncover the position of pipes, ordnance or ore bodies, for example. This process is normally cheaper, safer, faster and less destructive than digging up the ground to see what is there.
Magnetics surveys measure minute changes in the Earth’s magnetic field. Discontinuities and anomalies indicate the presence of faults, shears and igneous intrusions. The minerals' industry uses magnetic surveys to seek out ore bodies, such as nickel, buried hundreds of meters below the surface.
The greatest challenge for explorers is to survey as efficiently as possible, while maximising data quality.
Gap GeoPhysics has invested decades of research and development into producing the world's best magnetometer receiver system, capable of the high sampling required to perform high definition magnetics surveys.
Electromagnetic (EM) Surveys
Time domain electromagnetic surveys involve the use of a transmitter to produce an alternating current through a wire loop that induces a secondary field (a decay) from the ground. This allows a sensor to determine subsurface electrical properties. The detection of conductivity anomalies can indicate the presence of metal deposits within a more resistive host, or other features, such as groundwater sources or salinity mapping.
The challenge with electromagnetic surveys is to generate as high a possible excitation source (current in the wire) as this will directly effect the noise floor of the survey.
For this purpose, Gap GeoPak has developed the world's most advanced high power transmitter systems. Gap GeoPhysics offers a number of highly developed surface electromagnetics systems, as well as borehole systems.
Induced Polarisation (IP) Surveys
Induced Polarisation (IP) is a survey technique where electrodes induce and measure a potential field in the ground. From this data, values such as the soil chargeability and apparent resistivity can be measured. Data is typically displayed in colour-by-amplitude charts of vertically aligned 'pseudosections' of the ground.
Having a powerful transmitter that can handle difficult ground conditions is vital in order to achieve reliable results.
Gap Geophysics offers advanced IP hardware for better quality data.
Sub-Audio Magnetics (SAM) Surveys
Gap GeoTek has developed a survey technique that combines both the magnetic technique and the electromagnetic technique into the one survey - producing double the data of traditional surveys, without sacrificing on data quality or survey efficiency.
Read more about SAM surveys here.