HORMIGA, Formation

TERTIARY (Oligocene to middle Miocene)

State 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 term Hormiga f ormation was given by A. Salvador in 1947 (private report) to the lower part of the Betijoque group exposed on Quebrada de la Hormiga, about 6 kilometers northeast of Betijoque.

According to Salvador, the Hormiga formation is 907 meters thick and consists mainly of interbedded mottled clays, claystones and occasional sandstones. The base of the formation, conformably underlain by the Paují formation, is in the Quebrada Bijagual, 120 meters upstream from its junction with the Quebrada de la Hormiga. In the Quebrada de la Hormiga, 850 meters upstream from its junction with the Quebrada Arenosa, the top is conformably overlain by the Vichú formation. The formation crops out along a belt, 1.5 to 2 kilometers wide, crossing the quebradas de la Hormiga and La Vichú. Although the formation is apparently barren of fossils in this area, the stratigraphic position suggests that it is probably Oligocene to middle Miocene. The upper part of the Hormiga formation is equivalent to the Isnotú formation of Sutton (1946, p. 1706-1707) whereas the upper portion of the lower part appears to correlate with the Palmar formation which underlies conformably the Isnotú after Sutton (1946, p. 1701). However, Mencher et al. (correlation chart) consider the Hormiga formation older than the Isnotú sediments and correlate only its upper part with the Palmar formation.

Gustavo Feo-Codecido