CERRO CORAZON, Beds

See CARATAS, Formation

CARATAS, Formation

TERTIARY (Paleocene to ?middle Eocene)

State of Anzoátegui, Venezuela

Author of name: H. D Hedberg, 1937a.

Original reference: H. D. Hedberg, 1937a, p. 243-244.

Original description: ibid.

The Caratas member was named by Hedberg (1937a, p. 243-244; 1937b, p. 1994-1996) after the Quebrada de las Caratas, a sidebranch of the Río Querecual. The term was originally used to designate the upper unit of the Santa Anita formation exposed on Río Querecual, between the top of the underlying San Juan sandstone, at the mouth of the Quebrada San Juan, and the base of the overlying Merecure formation, about 600 meters downstream from the Paso Santa Anita. The exposed section is about 2,500 feet thick. The sediments are generally glauconitic and calcareous or dolomitic, and consist of fine to medium-grained sandstones, gray and brownish gray shales, siltstones and limestones. Later, Hedberg and Pyre (1944, p. 1215) restricted the term Caratas member to the resistant unit, about 1100 feet thick, of calcareous and dolomitic siltstones and glauconitic sandstones at the top of the formation, whereas the underlying glauconitic shales member, about 900 feet thick, was called Vidoño shale. The Santa Anita formation was later raised to the rank of group (Liddle, 1946, p. 280) and its respective members (San Juan, Vidoño and Caratas) to formations (Hedberg, 1950, p. 1193).

The Caratas formation is in conformable stratigraphic contact with the underlying Vidoño formation. However, the nature of the contact with the underlying Merecure group is not very clear, and has given rise to controversial interpretations. According to Hedberg (1950, p. 1195), on the Río Querecual there are about 100 feet of shaly to gritty calcareous concretionary sediments which appear to form a transition zone between the Caratas formation and the overlying Merecure group. Farther east, along the southern edge of the Serranía del Interior, the Caratas formation thickens and becomes increasingly sandy with even some gritty and pebbly beds in its upper part. On the ríos Aragua, Orégano and others, there is a transition zone in which calcareous siltstone of the Caratas formation alternates with quartzitic sandstone like that of the Los Jabillos formation of the Merecure group. On the other hand, in the Barcelona area and as far east as Río Capiricual, the Caratas formation is relatively thin and in unconformable contact with the overlying Merecure group.

Shaly portions from the lower part of the Caratas formation contain a poor fauna of small foraminifera of which most of the species are also present in the underlying Vidoño formation (Hedberg and Pyre, 1944, p. 14). Sediments from the upper part carry nummulites and orbitoids, but the stratigraphic position of these beds is disputed. A limestone with numerous specimens of "Venericardia planicosta" and believed to belong to the Caratas formation, is exposed near Cerro Corazón north of Urica; these beds are termed Cerro Corazón beds by Senn (1940, p. 1580). On this paleontological basis and due to the apparent transition of the Caratas formation into the upper Elocene part of the Merecure sediments, a Paleocene - middle Eocene age has been suggested by Hedberg (1950, p. 1195). However, González de Juana (1947, p. 697) notes the possibility that the Santa Anita group may be entirely upper Cretaceous, with a considerable depositional hiatus prior to the upper Eocene transgression.

G. Feo-Codecido