163-G 3.1

Tectono-stratigraphic evolution of the intermontane Salta basin and Chaco-Paraná foreland basin: characterization and evolution of petroleum potential

The evolution of the inter-mountain Salta basin is related to the evolution of the Central Andes. An intracontinental rift was formed by extensional processes and subsequently filled by up to 5500 m sediments from the Neocomian to the Paleogene intercalated by minor volumes of magmatic rocks. This complex constitutes the Salta group. Paleoenvironmental analysis reveals depositional history controlled by tectonic and climatic changes. Deformation of the basin began at the end of the Eocene and resulted in a rapid transition from a rift basin to a foreland basin filled by synorogenic continental deposits. The Chaco-Paraná Basin comprises the undeformed Chaco-Parana plain to the east, and the Subandes, Sierras Pampeanas, and the ranges of the Santa Barbara System to the west. The basin comprises >10 km of sediments spanning the Silurian to the Present. It is asymmetric, with a total stratigraphic thickness of Cenozoic rocks >7.5 km deposited at the western margin that thin eastward. Deformation of the Subandes and the Salta Basin developed since the Eo-Oligocene; and is characterized mainly by in-sequence, thin-skinned thrusting that includes ramp anticlines and passive roof duplexes separated by thrust faults and synclines, although Plio-Pleistocene out-offsequence thrusting has also been reported. The Subandes are home to several major gas discoveries during the last 20 years. The Chaco-Paraná foreland basin, as a frontier exploration area, has a high resource potential (some assessments attribute almost one third of Argentina’s total unconventional hydrocarbon potential to this basin), although exploration concepts are largely unproven. By combining 3D petroleum system modeling techniques with detailed source rock and petroleum-accumulation information, volumetric assessments of petroleum potential can be produced at different scales for basin wide assessments of the possible resource potential. We plan to investigate the evolution of the inter-mountain Salta basin and the Chaco-Parana Basin to deconvoluting its burial and thermal histories as well as source rock maturation, petroleum generation, migration, accumulation and leakage. A detailed basin modeling study is planned which integrates the tectono-stratigraphic evolution, timing of major unconformities, spatiotemporal migration of depocenters, source-rock occurrence and type to elucidate the hydrocarbon generation and migration history of this basin. Special focus will be put on the climatic and tectonic processes operating in the sediment source areas to determine the main variables and forcing conditions controlling the stratigraphic architecture and the distribution of source rocks. Within this context including all information available on the crustal evolution of the NW of Argentina is a pre-requisite. Especially the buildup of the Andes, and fault reactivation and thrusting along the basin margins are important factors in controlling both the burial as well as the maturation and petroleum migration histories. This project will provide an integrated and concise description of the evolution of Salta and Chaco-Parana basin petroleum systems. The project will cooperate closely with projects [G 3.3] and [G 3.4] to define boundary conditions for basin modeling and detailed description of the tectono-stratigraphic and sedimentary evolution of the basin.