1. n. [Geology]

An entity or property that differs from what is typical or expected, or which differs from that predicted by a theoretical model. May be the measurement of the difference between an observed or measured value and the expected values of a physical property.

Anomalies can be of great interest in hydrocarbon and mineral exploration because they often indicate hydrocarbon and mineral prospects and accumulations, such as geologic structures like folds and faults.

• Geochemical anomalies at the surface of the Earth can also indicate an accumulation of hydrocarbons at depth.
• Geophysical anomalies, such as amplitude anomalies in seismic data and magnetic anomalies in the Earth's crust, can also be associated with hydrocarbon accumulations.

Alternate Form: anomalous

See related terms: aeromagnetic survey,  amplitude anomaly,  Bouguer anomaly,  bright spot,  caprock effect,  dim spot,  downward continuation,  exploration,  fan shooting,  fault,  fold,  free-air correction,  gravity anomaly,  halo effect,  play,  prospect,  velocity anomaly