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Abstract: El Baul Arch: Has It Divided the Oriental and Barinas-Apure Basins?

Adolfo Portilla

In the central part of Venezuela, located to the east of the Venezuelan Andes, to the south of the Coastal Range, and to the north of the Guyana shield there is El Baul Arch. This ancient structural feature outcrops in El Baul village. The purpose of this study was to establish whether this arch separated the Barinas-Apure Basin from the Eastern Venezuelan Basin during the Cretaceous to the Pleistocene and, as well, its role in the sedimentary process within these basins.

In spite of the new high resolution seismic, air-magnetic and well data, obtained from 1978 to 1983, the knowledge about this arch is incomplete. Four second-order sequences were defined in both sides of the arch, using seismic stratigraphy concepts. Along with seismic-tectonics those sequences were used to establish the nature of the geological processes across the arch, and their relationship with the Andes uplift and the Caribbean Nappes.

Sedimentary sequences from Upper Cretaceous through the Pleistocene are continuous over the arch, except where they have been washed out by erosion.

El Baul Arch never divided these basins. Therefore, they have been one tectonic-stratigraphic unit. The arch was uplifted since the Late Cretaceous-Early Eocene until possibly Middle-Late Eocene. Then it was submerged during the Oligocene-Early Miocene. The Arch was uplifted again during the Middle Miocene to the Pleistocene.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela