Airborne geophysical survey is a process for measuring the variation of several key physical or geochemical parameters of the earth.
The most important parameters measured are conductivity (which is the inverse of resistivity), magnetic susceptibility, density, and radioactive element concentration. The airborne systems used at Helica to measure these parameters are a magnetometer and a gamma-ray spectrometer (AGS).
Magnetic surveys map the three dimensional variation in conductivity, caused by changes in mineralogy, pollutants, water content or salinity, among other causes. Airborne magnetic surveys map the variation of the magnetic susceptibility, generally due to changes in the magnetite content of the rock.
Gamma-ray spectrometric surveys measure the radiation of one or more natural radio-elements, such as potassium, uranium, thorium, or a specific man-made radioelement.
Magnetic and Gamma-ray systems are usually installed together on same airborne platform for a multi acquisition flight mission.