1. n. [Geology]

The state of a source rock with respect to its ability to generate oil or gas. As a source rock begins to mature, it generates gas. As an oil-prone source rock matures, the generation of heavy oils is succeeded by medium and light oils. Above a temperature of approximately 100 degC [212 degF], only dry gas is generated, and incipient metamorphism is imminent. The maturity of a source rock reflects the ambient pressure and temperature as well as the duration of conditions favorable for hydrocarbon generation.

See: generation,  hydrocarbon,  immature,  metamorphism,  natural gas,  oil-prone,  overmature,  petroleum,  postmature,  pyrolysis,  source rock,  vitrinite,  vitrinite reflectance