ICOTEA Formation

TERTIARY (Oligocene)

State of Zulia, Venezuela

Author of name: Geologists of the Venezuela Gulf Oil Company, 1928.

Original reference: H. D. Hedberg and L. C. Sass, 1937, pp. 97-99.

Original description: ibid.

Hedberg and Sass (1937, pp. 97-99) stated that the name Icotea formation was proposed for the dominantly white sandstone and claystone unit immediately overlying the Eocene strata in wells drilled in the vicinity of Punta Icotea on the east side of Lake Maracaibo between the villages of La Rosa and Ambrosio. They described the formation as consisting largely of white massive siltstone and claystone which, in the upper part of the formation, may be locally mottled in dull shades of red, green, brown, purple, yellow, and gray, representing a transition to El Fausto lithology. There are occasional beds of green or gray shale and sandstone. A thickness of 0-50 meters on the west side of the lake was given by Hedberg and Sass. They pointed out that no fossils were found on the west side of the lake. Hedberg and Sass stated that the formation rests unconformably on various horizons of the Eocene. It grades laterally westward from the lake area into the mottled sediments of the El Fausto formation. In the type locality and on the western edge of the lake it is conformably overlain by the La Rosa formation, but farther to the west, El Fausto sediments appear between the Icotea and La Rosa formations, and the Icotea gradually tongues out completely into the El Fausto. The Icotea is of non-marine origin. Hedberg and Sass believed the formation to be upper Oligocene in age.

Haas and Hubman (1937, p. 126-127) described the formation as consisting of hard, massive, occasionally carbonaceous, white to light gray siltstones and claystones. These are locally mottled with light green, yellow and brownish red, particularly near the base of the formation. They pointed out that the Icotea is rather limited in extent and is, more or less, confined to the old basins on the Eocene surface. Haas and Hubman cited a maximum overall thickness of 600 feet in the Icotea syncline, in the northern part of the Bolívar Coastal field.

Liddle (1946, p. 404-405) stated that the formation is probably lower and middle Oligocene in age.

Sutton (1946, p. 1688-1689) pointed out that the Icotea formation is unconformably overlain by the La Rosa formation. He stated that the Icotea is locally present throughout the northern part of the Bolívar Coastal field and extends westward across Lake Maracaibo where its thickness does not exceed 50 meters. Sutton gave a probable middle Oligocene age to the formation.

Mencher et al. (1951, p. 21) stated that the age of the formation is uncertain but generally thought to be approximately middle Oligocene. On their correlation chart they showed the age of the Icotea to be upper lower and lower middle Oligocene (?).

Leo Weingeist