VICHU, Formation

TERTIARY (middle Miocene)

States of Trujillo, Venezuela

Author of name: A. Salvador, 1947 (private report).

Original reference: E. Mencher et al., 1953, correlation chart of Venezuelan geological formations.

Original description: none published.

Although published originally by Mencher et al. in 1953 (correlation chart), the name Vichú formation was introduced by A. Salvador in 1947 (private report) to designate the middle part of the Betijoque group exposed on Quebrada La Vichú, just east of Betijoque.

According to Salvador, the Vichú formation is 2,135 meters thick and is made up principally of sandstones, claystones and very occasional conglomerates. The base of the formation, conformably underlain by the Hormiga formation, is in the Quebrada La Vichú, 1,600 meters northwest of the bridge crossing on the old mule trail from Betijoque to Isnotú. The top, conformably overlain by the San Alejo formation, is in the same creek, approximately 900 meters upstream from the junction with the Quebrada Miquimbós. The formation crops out along a belt 4 kilometers wide, through the middle of the Betijoque badland area. No fossils, except for plant remains, were found in the Vichú formation. On the basis of paleobotanic evidence (Berry, 1921) and its stratigraphic position, the formation appears to be middle Miocene. The Vichú formation correlates with the lower part of Sutton's (1946, p. 1709-1710) Betijoque formation. Although the Vichú sediments are believed to be younger than the Isnotú formation, Mencher et al. (correlation chart) consider these two formations equivalent.

Gustavo Feo-Codecido