BASIN EVOLUTION AND PROSPECTIVITY OF THE ARGENTINE CONTINENTAL-MARGIN

Nine Mesozoic-Tertiary basins of different orientations lie along the Argentine continental margin. over a distance exceeding 2,000 km: thes e are the Salado, Colorado, Valdes, Rawson, San Jorge offshore, North Malvinas (San Julian), West Malvinas and Magallanes (Austral) Basins o n the Continental Shelf, together with the Continental Slope. These ba sins formed following the latest Jurassic - Early Cretaceous extension that accompanied the onset of South Atlantic rifting. Strain was modi fied by earlier basement fabrics, with consequent transtension. The Ca pe Fold Belt (Permo-Triassic) provided a NW-SE grain to pre-Mesozoic c over off NE Argentina. In the central-southern sector, several phases of oblique NEwards Pacific subduction and terrane accretion during the Permo-Triassic formed back-arc basins and volcanic belts, producing a more variable fabric orientated close to NNW-SSE. Atlantic basin fill , of Lower Cretaceous-Tertiary clastics, was deposited as a result of rift-shoulder erosion and Atlantic flooding following eastward tilting . Basin fill thickness is typically 2-4 km, but locally exceeds 6km. T he hydrocarbon potential of these basins hinges as much upon the prese rvation of source rocks within the pre-rift succession as it does on t hat of those within the base-rift succession, and subsequent Atlantic anoxic events.