Abstract: In this study, based on plate tectonic evolution and using seismic and geological data, formation and evolution of prototype basins on the conjugated passive continental margins of the South Atlantic were studied, and ancient sedimentary environment and its controls on the forming conditions of large oil and gas fields were compared segmentwise according to variations in basin architecture, and finally the passive continental marginal basins were divided into “three segments” and “four types” to reveal the accumulation law of giant oil and gas fields. As our study showed, the “four types” of basins on “three segments” had gone through three prototype stages: early intracontinental rifting, intermediate intercontinental rifting, and late drifting passive continental margin. In the southern segment, thin sediments in the “rifttype” basin that formed in the drifting stage, developed into the large “rift structuralstratigraphic” oil and gas fields. In the middle segment, the “saltyriftdepressiontype” basins were filled with intercontinental rift salt rocks in the intermediate stage; and upper and lower sections are marine and lacustrine sediments from the drifting and rifting stages, respectively, possibly of highquality. Utilizing salt rock and marine shale as caprocks, the giant oil and gas fields of “presalt carbonate and postsalt turbidity sands” were developed. Finally, in the northern segment, thick marine sediments in the drifting stage in the “depressiontype” basin, affected by “narrow shelves” and “steep slopes” and controlled by the transform fault, developed into the large “deepwater turbidity fan group” oil and gas fields on the basin margin. Our study further showed in the Niger highconstructive “deltatype” basin, unique deltagravity flow sandstone reservoirs have been formed, and giant oil and gas fields are identified in the innerring rollover anticline delta sandstone, the middle mud diapir and the outerring thrust crust.

Key words: South Atlantic, passive continental margin basin, prototype basin, basin architecture, giant oil and gas fields