ANALOGÍAS ENTRE LA SIERRA SILVA Y EL ANTICLINAL PERALES: IMPACTO EN EL ANÁLISIS ESTRUCTURAL DE LA FAJA PLEGADA DE SAN BERNARDO (CUENCA DEL GOLFO SAN JORGE)

ALLARD JOSÉ; FOIX NICOLAS; BUETI SEBASTIAN; FERREIRA PITTAU MARIA LEONOR; ATENCIO MARIO

Mendoza

Congreso; 10 Congreso de Exploración y Desarrollo de Hidrocarburos; 2018

Instituto Argentino del Petróleo y del Gas

Analogy between Sierra Silva and Perales Anticline: Impact in the Structural Analysisof the San Bernardo Fold Belt (Golfo San Jorge Basin)The San Bernardo Fold Belt (SBFB) is a region of the Golfo San Jorge Basin (GSJB) characterizedby N-S to NNW-SSE folds linked to positive tectonic inversion. Almost all of these folds have amultiphase construction origin. The Sierra Silva (SS) is among the most characteristicmorphostructure of the SBFB. The topographic and structural architecture of SS expose a NNESSW complex fold, segmented by faults oblique to the fold axis, these brittle structures have lateraland vertical displacement components. These faults are interpreted as secondary faults partiallyreactivated and exhumed during the cenozoic tectonic inversion. The morphology of this fold andits tectonostratigraphic evolution contribute fundamental evidences to extrapolate them to theanalogues structures in subsurface.Southern to the Senguerr River elbow, the SBFB is developed in the subsurface of the GSJBwhere many of these fault-fold structures are oil bearing structural traps. In particular, PeralesAnticline (PA) constitute one of the main structures of the Los Perales-Las Mesetas block. Thesestructure has been systematically studied and developed since its discovery in 1934. Although thisscenario, at the present time the validated structural interpretations are contrasting andantagonistic. On one hand it is proposed a tectonostratigraphic evolution where the CastilloFormation (Albian-Cenomanian) represent a sin-inversion unit, while on the other hand, that unit islinked to the extensional-thermal subsidence of the basin.The present contribution makes the geometric, kinematic and dynamic structural analysis of bothfault-related folds to define analogies and differences between them. In cross sectionsperpendicular to the folds axis, the strata (SS) and the sismo-sequences (PA) do not showstratigraphic wedges linked to growth-strata towards the folds hinge. This characteristic, in additionwith the absence of progressive unconformities, sustain an uplift after the deposition of the ChubutGroup base. This context is support with inlines parallel to the main fault of PA, where thatstratigraphic interval shows an increasing in the stratigraphic thickness and reflectors divergencetoward the crest of the braquianticline. At the same time, the transverse to oblique secondary faultsshow evidences of sin-extensional activity, so them can be interpreted as cretaceous extensionalbrittle structures reactivated during the inversion. This architecture is analogous to the recognizedat surface at SS.