In geophysics, a magnetic anomaly is a local variation in the Earth’s magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying material.
Proterozoic rocks have been identified on all the continents and often constitute important sources of metallic ores, notably of iron, gold, copper, uranium, and nickel.
Over the last 200 years, the magnetic field has lost around 9% of its strength on a global average. A large region of reduced magnetic intensity has developed between Africa and South America and is known as the South Atlantic Anomaly.
Magnetic Anomaly
Proterozoic Eon
Weakened geomagnetic field:
Biogenic molecules
aka fake buzz word