1. n. [Geology, Geochemistry, Shale Gas]

A type of geochemical analysis in which a rock sample is subject to controlled heating in an inert gas to or past the point of generating hydrocarbons in order to assess its quality as a source rock, the abundance of organic material in it, its thermal maturity, and the quality of hydrocarbons it might generate or have generated. Pyrolysis breaks large hydrocarbon molecules into smaller molecules. This process is used to determine the quality of shale as a source rock and is instrumental in evaluating shale gas plays.

See: generation,  geochemistry,  maturity,  source rock

2. n. [General Terms]

Thermochemical breakdown of organic matter by heating in the absence of oxygen.