The Role of Intraplate Foreland Deformation in the Petroleum Systems of Neuquén Retroarc-Foreland Basin, Argentina

Mosquera, Alfonso¹, Victor Ramos² (1) Tecpetrol S.A, Buenso Aires, Argentina (2) University of Buenos Aires, Buenos Aires, Argentina

Mesozoic-Cenozoic intraplate deformation played a key roll in the evolution of the petro­leum systems of the Neuquen retro-arc foreland basin (EUR 9700 MMBOE), one of the most prolific basins of southern South America. Intraplate deformation was the result of the inter­action of Paleozoic basement fabrics developed during the accretion of three terranes to the Gondwana, Early Jurassic hemigrabens and changes in the convergence vectors between the Aluk, Farallon, and Nazca oceanic plates and the Gondwana or South American continen­tal plates. During the Aluk compressional stage (Early Jurassic – Valanginian, main stress in the N-NW sector) the southern margin of the basin was strongly uplifted by inversion and right lateral strike slip (Huincul system) deformation, while the two basin hinges were formed along less deformed the eastern margin (Entre Lomas System) and central part (Chihuidos system). The Aluk stage strongly controlled the area distribution and thickness­es of the source, reservoir and seal units of the most prolific petroleum systems, Molles and Vaca Muerta, and resulted in early trap formation and migration paths along the margins of the basin. The Farallon compressional stage (Valanginian-Miocene, more orthogonal WNW­ESE stress orientation), a westward retreat of the deformation along the southern margin, an increase of the inversion along the Entre Lomas system (Cenomanian), and the westward inception of the Agrio fold belt. It controlled the trap formation process along the margins Nazca stage, with orthogonal stress resulted in the development of the fold belt and broken foreland system, and the present day basin configuration