Deer-Boar Petroleum System at Critical Moment Raven A’ A Owens Marginal Teapot Reservoir Rock Pod of Active Source Rock Big Oil Just Hardy [the Deer-Boar is a fictitious name for a conceptual model petroleum system] Map view of the geographic extent of the Deer-Boar petroleum system at the critical moment (250 Ma).  Thermally immature source rock (Light green) is outside the oil window.  The pod of active source rock (pink) lies within the oil and gas windows.  Critical moment refers to the time that best depicts the generation-migration-accumulation of hydrocarbons in a petroleum system. In fact, it is an interval of time rather than a geologically instantaneous moment. Lucky David Immature Source Rock Zero Edge of Reservoir Rock Magoon and Dow, 1994