The foreland backarc Neuquen basin in southwestern Argentina includes four sedimentary cycles of Jurassic-Eocene age. (1) The Cuyo cycle includes black, organic-rich shales overlain by coastal and fluvial siliciclastics. (2) The Lotena-Chacay cycle comprises excellent siliciclastic reservoir rocks overlain by thick evaporites, all deposited on a platform. (3) The Andic cycle includes hydrocarbon-bearing basal alluvial fan deposits and transgressive sandstones that are overlain by organic-rich shaly carbonates, the main hydrocarbon source rock. This cycle also has platform to coastal carbonates overlain by fluvial deltaic clastics and neritic black shales. Evaporitic facies complete this important cycle. (4) Finally, the Rio Grande cycle comprises fluvial and alluvial sili iclastics, evaporites, and coastal or shallow platform shales and carbonates. These four sedimentary cycles represent most of the basin fill.

The western area of the basin shows a belt of north-south trending thrust cut folds built in the original foredeep basin during Andean tectonic phases. The eastern area comprises a platform, hinge line, and deep embayment separated from the western area by a megasuture.

Three petroleum systems are in two sedimentary cycles, the Cuyo and the Andic, of Jurassic-Early Cretaceous age. The second petroleum system within the lower Andic cycle contains the most hydrocarbons. All systems in the eastern area reached their critical moment during the late Eocene, and in the western area during the late Tertiary. Destruction of parts of these petroleum systems occurred through abnormal heat flow from volcanism and by erosion. Although the heat flow destroyed some hydrocarbons, in other areas it enhanced kerogen maturation and thermally cracked oil to gas. Destruction by erosion was important in uplifted areas.