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Bruno De Toni1, Juan Di Croce1, Renzo Violino1, Martha Jaimes1
(1) PDVSA EP, Caracas, Venezuela

Abstract: Multiphase Deformation of Thick Skinned Structures in Western Venezuela: Case Studies

In the Maracaibo - Barinas basin, significant hydrocarbon reserves have been discovered within folded and faulted complex structures involving the deep seated basement. The major oil producing structures, are associated to the reactivation in compressive and extensional phases of inherited basement controlling fault systems of Paleozoic (?) and Jurassic ages. The preservation of several unconformities as well as the relation with pre-syn and postkinematic sediments, led to compare the timing and modes of multiphase deformations with the different stages of basin evolution and the hydrocarbon habitat. Recent subsurface imaging clearly documents the initial configuration and sedimentary infill of Jurassic-early Cretaceous episode of rifting with the subsequent passive margin sequence. Low relief late Cretaceous basement involved reverse faults are clearly imaged on seismic reflection profiles from the southwestern portion of Lake Maracaibo. This compressive deformational phase does not reactivate older structures and occurs prior to the infilling of the Caribbean foredeep clastic wedge. Active normal faulting and flexural subsidence during Paleogene times was superimposed on to older basement involved faults. Some of the pre-existing Jurassic faults were reactivated but new early Eocene high angle extensional structures were developed controlling the sedimentation in the Caribbean foreland. Late Eocene and Neogene tectonic inversions modified the early extensional architecture of the basin. The foreland frontal monoclines of folded belts in western Venezuela, relates to highly complex poorly understood reactivation of pre-existing fault systems involving basement. Even though they still remain under explored they are highly attractive frontier areas for future exploration plays.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana