A Magnetic Survey is a geophysical exploration technique used to measure variations in the Earth's magnetic field caused by differences in the magnetic properties of subsurface rocks and minerals. It is widely employed in mineral exploration for bauxite, gold, iron ore, and diamond deposits.
The survey is conducted using instruments called magnetometers, which record subtle changes in magnetic field intensity. These variations may indicate the presence of magnetic minerals such as magnetite or geological structures associated with mineralization.
Magnetic surveys can be performed from the ground, aircraft, drones, or marine platforms. Airborne magnetic surveys are particularly effective for covering large exploration areas quickly and cost-effectively. Data collected during the survey are processed to create magnetic maps that reveal geological features hidden beneath soil, vegetation, or sediment cover.
In iron ore exploration, magnetic surveys are highly valuable because magnetite-rich formations produce strong magnetic anomalies. In gold exploration, magnetic data help identify structures such as faults, shear zones, and intrusive bodies that may control mineralization. Diamond exploration programs often use magnetic surveys to locate kimberlite pipes.
The technique is non-invasive, relatively inexpensive, and capable of providing extensive geological information. Magnetic surveys are frequently integrated with geological mapping, drilling, gravity surveys, and geochemical programs to improve exploration targeting and reduce exploration risk.