magnétométrie

Magnetometry is a geophysical method used to measure and map variations in the Earth's magnetic field. These variations, or anomalies, are caused by differences in the magnetic properties of subsurface rocks and geological structures. Different minerals within the Earth's crust possess varying degrees of magnetization, and their concentration and distribution create localized magnetic fields that deviate from the Earth's normal geomagnetic field.

Magnetometers are the instruments used to detect and record these magnetic field strengths. There are several types of magnetometers, including fluxgate magnetometers, proton magnetometers, and alkali vapor magnetometers, each with its own sensitivity and operational principles. Data collected from these instruments can be processed and interpreted to create magnetic maps. These maps reveal patterns that can indicate the presence of ore bodies, faults, intrusions, or other geological features.

Magnetometry has a wide range of applications. It is extensively used in mineral exploration to locate deposits of iron ore, nickel, copper, and other magnetic minerals. It also plays a crucial role in hydrocarbon exploration, where magnetic anomalies can help identify basement structures and sedimentary basins. Archaeologists use magnetometry to detect buried structures, hearths, and kilns, as heated materials can retain a magnetic signature. Furthermore, magnetometry is employed in unexploded ordnance detection and in geological mapping to understand the subsurface geology of an area.