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Structural Evolution of Convergent Margin of Central Peru and Its Relationship with Petroleum Systems of the Forearc Salaverry Basin

Romero, Darwin; Valencia, Kiko1; Alarcon, Pedro; Llerena, Carlos E.; Borda, Edgar; and Rojas, Javier
1[email protected]

The convergent margin of central Peruvian coast between Chiclayo and Lima cities presents Cenozoic sedimentary forearc basins (Trujillo and Salaverry), limited by structural highs and affected by normal, reverse and strike slip faults.

With the aim of define the Petroleum system and evaluate the hydrocarbon potential of the frontier exploratory Salaverry basin, Savia Peru studied field geology as well as gravimetric/magnetic surveys and abundant 2D/3D Seismic information. As a result, it was defined both, the stratigraphic column of continental margin basin, consisting of Precambrian, Carboniferous basement filled by Jurassic and Cretaceous rocks, and forearc Cenozoic basin, as well as the reconnaissance of two potential Petroleum Systems related to Tithonian and Albian potential source rocks and Mesozoic /Cenozoic reservoirs.

Regional structural analysis shows the existence of two uplifted mega blocks of NW-SE direction, one is known as the Cordillera de la Costa-Outer Shelf High (CC-OSH), it is 20 km wide on average and located approximately 120 km from the trench. The other high, is located further west at 50 km on average from the trench, it is known as the Upper Slope Ridge (USR).

The Peruvian offshore forearc is characterized by dominant extensional tectonics, punctuated by some contractional episodes. That extensional regime is the result of the strong coupling between the oceanic slab and the overriding plate. The normal faults are originated by crustal subduction erosion along the margin. This extensional regime is only interrupted in Middle Miocene times by the collision of the Nazca aseismic ridge against the trench (to present day), which produced the tectonic inversion of the normal faults.

Finally, the petroleum system analysis of the Salaverry basin allowed identifying very good hydrocarbon prospectivity because all petroleum systems elements have been recognized and generation-migration processes have been demonstrated through the identification of at least four potential kitchens and sampling/analysis of three oil seeps.

 

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