Sedimentary Provinces of Africa, Middle East, and South America, Classification and Hydrocarbon Potential

Frank J. Picha

In all, 243 sedimentary provinces (basins, foldbelts) were analyzed, classified, and graphically displayed on continental maps (1:5,000,000). An elaborate system of symbols and colors shows the plate tectonic history of each province, the stratigraphic extent and thickness of the sedimentary fill, the type of basin-forming and basin-modifying tectonics, and the distribution of oil and gas fields.

The provinces are grouped into five classes which correspond to principal plate tectonic settings: (1) intracontinental basins (rifts, sags), (2) divergent margins, (3) convergent margins, (4) oceanic basins, and (5) orogenic belts and associated basins (e.g., foreland and intermontane basins). The history of each province is determined by critical stages of the plate tectonic cycle: (1) rifting, (2) drifting and sagging, (3) subduction and continental collision. Simple basins form during a single stage of a plate tectonic cycle, e.g., the Tertiary Red Sea rift. Polyhistory provinces have several stages of a primary cycle (e.g., the divergent continental margins of west Africa overlap the intracontinental rift stage). In more complex provinces the history may extend over two cycles (e g., northwest Africa with elements of the Paleozoic cycle ending at the Hercynian orogeny overlain by the Mesozoic and Cenozoic cycle which ends with the Alpine orogeny).

The provinces affected and/or associated with continental collision such as the folded and faulted forelands and foreland basins contain more than 80% of all proven reserves of hydrocarbons.

The maps reveal many aspects of the Phanerozoic history on a continental scale relevant to exploration for hydrocarbons.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.