Basement and Paleozoic rocks of the Venezuelan Llanos basins*
Published:January 01, 1984
Gustavo Feo-Codecido, Foster D. Smith, Jr., Nelson Aboud, Estela de Di Giacomo, 1984. "Basement and Paleozoic rocks of the Venezuelan Llanos basins", The Caribbean-South American Plate Boundary and Regional Tectonics, William E. Bonini, Robert B. Hargraves, Reginald Shagam
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The igneous and metamorphic rocks of Venezuela may be classified in three geographic units: a southern Precambrian Shield, an intermediate belt of Paleozoic age and a northern border of Mesozoic to Tertiary age. The shield is exposed in the south; it extends northward under a sedimentary cover to an inferred contact with the metamorphosed Paleozoic or Mesozoic-Tertiary rocks. South of this contact, in the eastern states of Anzoátegui and Monagas, the shield's oldest known sedimentary cover is of Cretaceous age; to the west, it is of Cambrian age.
A graben is identified in the State of Guarico, located approximately along the contact of the Paleozoic basement with the Precambrian Shield. It contains a 2,390 m (7,840 ft) column of sedimentary rocks of Carboniferous and Jurassic age, not previously identified in the Barinas-Apure and Eastern Venezuela basins. Preliminary interpretation of recently acquired aeromagnetic data indicates that this feature forms part of a much longer graben, hitherto not known, which may extend westward from near Barcelona, Anzoátegui, to the Colombian border at approximately 70° 00' West Longitude, 7° 10' North Latitude, a distance of 600 km (375 mi).