SANTA ANITA, Group

UPPER CRETACEOUS to LOWER TERTIARY

State of Anzoátegui, Venezuela

Author of name: C. González de Juana and H. D. Hedberg, 1937.

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

Original description: ibid.

At the suggestion of C. González de Juana, the Santa Anita formation was named by Hedberg (1937a, p. 243; 1937b, p. 1994-1995) after the Paso Santa Anita, a crossing of the Río Querecual. The term was originally used as a formation name to designate the sediments, in their type locality, between the top of the Cretaceous Guayuta group and the base of the upper Eocene part of the Merecure formation, 150 meters upstream and 600 meters downstream from the Paso Santa Anita respectively. The formation was originally divided into a lower San Juan sandstone member, composed of about 320 feet of a very hard, gray, fine to medium-grained sandstone, calcareous and glauconitic in its uppermost part, and an upper Caratas member, made up largely of about 2,050 feet of sediments generally glauconitic and calcareous or dolomitic, consisting of fine to medium-grained sandstones, gray and brownish-gray shales, siltstones and limestones.

Hedberg and Pyre (1944, p. 12-15) restricted the term Caratas member to the resistant unit, about 1,100 feet thick, of calcareous and dolomitic siltstones and glauconitic sandstones at the top of the formation, whereas the underlying glauconitic shale member, about 900 feet thick, was called Vidoño shale. The formation was later raised to the rank of group (Liddle, 1946, p. 280) and the respective San Juan, Vidoño and Caratas members to formations (Hedberg, 1950, p. 1193).

According to Hedberg (1950, p. 1194-1195), the contact between the San Juan formation (Santa Anita group) and the underlying San Antonio formation (Guayuta group) is frequently abrupt, but there is no reliable indication of unconformity. The contact of the Caratas formation with the overlying Merecure group appears to be transitional on the ríos Querecual, Aragua, Orégano and other streams, but in the Barcelona area and as far east as Río Capiricual, the Caratas formation is only a few hundred feet thick, probably due to erosional unconformity, and the contact is sharp and easily placed. Paleontological evidence indicates an Upper Cretaceous to Paleocene age for the Santa Anita group; however, its apparent transition into the upper Eocene part of the Merecure group suggests that the upper part of the Santa Anita group may be as young as middle Eocene. González de Juana (1947, p. 697) draws attention to the possibility that the Santa Anita group may be entirely Upper Cretaceous, with a considerable hiatus in deposition before the upper Eocene transgression.

Hedberg (1950, p. 1193-1194) reports that the Santa Anita group forms a more or less continuous series of outcrops along the southern border of the Serranía del Interior, from Puerto La Cruz in the west to Río Guayuta near Aragua de Maturín in the east. Eastward from Rio Guayuta, the Santa Anita group is completely overlapped by younger sediments. The group is missing in the Barcelona gap west of Barcelona, but westward from the vicinity of Rio Unare, its sediments are present along the northern edge of the basin.

In certain localities along the southern part of the Serranía del Interior, westward from the Anzoátegui-Guárico boundary, are isolated reef limestone hills or morros (Batatal, San Francisco de Macaira, San Sebastián, San Juan de los Morros, etc.) which are believed to belong to the Santa Anita group and appear to be a reef development in sediments of Caratas age (Hedberg, 1950, p. 1196). Evanoff (1951, p. 244-245) includes the morros of the Altagracia de Orituco region in his Macaira group.

The Santa Anita group includes a portion of what Liddle (1928, p. 216225) included in the Aragua sandstone of Garner (1926, p. 680).

Gustavo Feo-Codecido