Magnetics

Method

Magnetics is based on the characteristic of the earth's magnetic field to induce all matter, magnetic or non-magnetic, with magnetic properties (magnetic susceptibility). Rocks and other objects show a different magnetization depending on their material composition. This causes anomalies in the local magnetic field which can be mapped with a magnetometer. Significant signal changes can usually be obtained between igneous rocks and metamorphic or sedimentary rocks. Ores can be located by their ferromagnetic accessory minerals.

The shape and amplitude of an induced magnetic anomaly is generally a function of the orientation, geometry, size, depth, and magnetic susceptibility of the body as well as the intensity and inclination of the earth’s magnetic field in the survey area.

Instrumentation

We use a GEMSYS GSM-19 GW with differential GPS as a walking magnetometer, and a GEMSYS GSM-19 as a base station.

Application

In the mining sector Magnetics is mostly used for mineral investigations. Magnetics is a highly effective primary method for discovering dikes/veins/alteration zones, ore bodies, and kimberlite pipes. Size and shape of these targets can then be confirmed by 2D Resistivity / IP.

In some cases Magnetics can be used as an auxiliary geophysical method for placer prospecting: If paleochannels, seen in a 2D Resistivity profile, have high concentrations of magnetite they, can be effectively mapped with a magnetometer.