Middle Devonian barrier complex within the Pine Point lead-zinc ore field located within the immature to marginally mature zone with respect to petroleum generation. Certain of the host rocks of the ore field were deposited in highly reducing conditions such that organic matter of algal or microbial origin has been preserved to a remarkable degree. Yields of extractable (soluble) material relative to organic carbon are extremely high, which has resulted in the local migration of immature bitumens and heavy oil within the shallow regime. Polymerization of nitrogen, sulfur, and oxygen compounds, and asphaltenes. Biodegradation of bitumens is a relatively late process. The question of a genetic relationship between lead-zinc sulfide and organic matter remains open.--Modified journal abstract.