The Peruvian Subandean Fold and Thrust Belt: Structural Overview and New Geochronologic Constraints

Baby, Patrice¹; Calderon, Ysabel; Eude, Adrien; Louterbach, Mélanie; Quispe, Alejandro; Ramirez, Leonardo; Cotrinas, Jimmy; Gil, Willy; Espurt, Nicolas; Brusset, Stéphane; Roddaz, Martin; Brichau, Stéphanie; Calvès, Gérôme; and Bolaños, Rolando
¹[email protected]

The Peruvian Subandean fold and thrust belt presents a complex latitudinal structural partitioning, which induced the individualization of sub-basins characterized by different types of structural plays. This north-south structural evolution was controlled by the Paleozoic and Mesozoic paleogeographies and the slab subduction geometry variations. Recent 2D and 3D seismic data permits to precise some thrust systems geometries and to propose new structural balanced cross-sections. In the southern part, the thickening of the Paleozoic sedimentary prism generated major décollements and complex duplex structures and triangle zones with high hydrocarbon entrapment potential. In the northern part, thrust propagation is controlled by Mezosoic rift and sag basins, where the occurrence of evaporites layers have largely influenced the tectonics style. The most spectacular consequence of this 'salt' occurrence is the development of the 42 km overthrusting of the Huallaga orogenic front, which implies interesting perspectives for sub-thrust structural prospects. The neighboring sub-basins, as the Santiago and Northern Ucayali basins, are also deformed by the tectonic inversion of Triassic rift systems, which prolong to the north in the Marañon and Oriente foreland. One other features of this northern region is the Subandean reactivation of Late Permian deep thrusts structures evidenced in some seismic sections of the Marañon, Huallaga and Northern Ucayali basins. This Paleozoic thrust system is partially preserved and can constitute a new play for the Subandean exploration.

New geochronologic data, provided by thermochronology analysis and growth strata discovery in 2D and 3D seismic data corroborated by field observations, allow us to propose new scenarii for the Subandean thrusts propagation. These scenarii permit to precise the events charts of most of the Subandean petroleum systems. The new Subandean deformation timing evidenced in this study shows a significant pre-Neogene structuration leading to a better understanding of the large gas accumulation of the Camisea giant field.

The structural overview of the Peruvian Subandean zone and the new geologic constraints presented in this paper provide a better calibration of the Paleozoic and Mesozoic petroleum systems and new perspectives for future hydrocarbon exploration in this region.

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013