The Peruvian sub-Andean foreland basin system: Structural overview, geochronologic constraints, and unexplored plays

In the Peruvian sub-Andean foreland basin system, the construction of serial balanced cross-sections from a good set of structural data and an extensive knowledge of the stratigraphy and geodynamic evolution allow a more refined definition of the unexplored plays, as subthrusts, duplexes, or pre-Andean structures. Sequential restorations are proposed by coupling thermochronologic analyses with growth strata studies. The results show significant north-south variations in geometry, timing and rates of deformation, and foreland sedimentation. These latitudinal variations are not only related to the pre-Andean basins' inheritance but also to the interactions between thrusts propagation, erosion, and sedimentation. Thermochronologic ages correspond to the most recent thrust-related uplifts and are supplemented by the study of stratigraphic foreland basin records that can bring to light oldest tectonic events. North of the Peruvian sub-Andean zone, thrusts propagation is controlled by thick-skinned and thin-skinned salt tectonics. Northern thick-skinned tectonics has westward vergence and is inherited from a Middle Permian fold-and-thrust belt. To the south, thrusts deformation is largely controlled by the geometry of the preserved Paleozoic sedimentary wedge and becomes progressively thin skinned. Total sub-Andean shortening varies between 70 km (43 mi) in the north and 47 km (29 mi) in the south. Sub-Andean deformation started in the Late Cretaceous. After a period of quiescence during the middle Eocene, it reactivated and is still active. Three stages of sub-Andean deformation are clearly identified and help to define the preservation time in the suggested petroleum plays.