Leonardo Duerto¹
(1) PDVSA E y P, Caracas, Venezuela

Abstract: Tectonic Inversion in the Mountain Front of the Central Range, Venezuela

The area south of the Central Venezuelan Mountain Front and north of the El Baul Paleozoic basement high in Guarico State, is characterized by two inverted normal fault trends: a N20E trend towards the east, and a N60W trend on the west, close and parallel to El Baul arch. These lineaments are observed in satellite imagery, surface geology maps and seismic data. The initial normal movement of these faults was during Paleogene or even earlier for the western faults, with a reactivation during the Oligocene due to the foredeep subsidence.

The later thick-skined folding associated to the Mountain Front in the area has a N10E orientation and a 10 to 20 Km wavelength. The age of this compresional deformation is mostly post-Miocene.

Northeast trending normal faults were markedly inverted where they coincide with the propagation folding wavelength, since they are perpendicular to the direction of compression. In the case of the Northwest trending normal faults, they were mostly inverted in specific areas also coinciding with the wavelength of the folding; the inversion in this case is partiall due to the parallelism to the stress compressional vector.

The present study shows that normal faults are inverted following a deformation process as originally indicated by Bally´s model (1966) about compressive regimes.

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