ARAGUA, Formation

See ARAGUA, Sandstone

ARAGUA, Sandstone

UPPER CRETAOEOUS

State of Monagas, Venezuela

Probably synonym of SAN JUAN FORMATION.

Author of name: R. Arnold, 1913 (private report).

Original reference: A. H. Garner, 1926, p. 678, 680.

Original description: ibid.

Garner (1926, p. 678, 680) gave the hills just north of the village of Aragua de Maturín, State of Monagas, as the type-locality for the Aragua sandstone. He described the unit as a massive, coarse, conglomeratic, hard, white to reddish brown sandstone. Garner cited a thickness of approximately 1000 feet for the sandstone and considered it to be Eocene in age.

Liddle (1946, p. 347-352) included under the name of "Aragua formation" a predominantly shaly section as the lower part and the sandstone section referred to by Garner (1926, p. 678, 680) as Aragua sandstone, as the upper part. Liddle cited the Cerro Aragua, immediately to the northeast of the village of Aragua de Maturin as the best exposure for the "Aragua formation". He described the lower part of the formation as consisting of generally conglomeratic, thickly bedded sandstone. Liddle cited a thickness of 200 feet for the Cerro Aragua section. According to Liddle the "Aragua formation" lies unconformably on the Guayuta group and underlies middle Miocene beds unconformably. Liddle claimed that at Cerro Corazón, a short distance north of the village of Urica in the State of Anzoátegui, some calcareous members of the "Aragua formation" carry many "Venericardia planicosta Lamarck". The finding of this species induced Liddle to give a lower or middle Eocene age to these beds.

Hedberg (1950, p. 1194) mentioned in his discussion of the San Juan sandstone that this unit thickens towards the east at the expense of the overlying Vidoño shale to more than 1000 feet of fine to coarse-grained sandstone. Hedberg pointed out that the San Juan formation is known as far east as Aragua de Maturin, where a large part of the "Aragua sandstone" of Cerro Aragua belongs to the San Juan formation. He mentioned that the unit at Cerro Aragua consists of 2000 feet of sediments. There the cherty beds and thin sandstones of the upper Guaynta group grade upward transitionally on the flanks of Cerro Aragua through a section of alternating medium-bedded and thin-bedded sandstones and sandy shales to the thick series of massive fine to coarse-grained sandstones which form the upper part of the hill. According to Hedberg, the San Juan sandstone is conformably underlain by the Guayuta group. Hedberg considered the San Juan sandstone to be Upper Cretaceous in age.

These comments of Hedberg (1950, p. 1194) suggest that the Aragua sandstone, as defined by Garner, is probably synonymous with the San Juan sandstone, as defined by Hedberg, and that the San Juan sandstone of Hedberg represents a large part of the "Aragua formation", as defined by Liddle, and not of the "Aragua sandstone" as stated by Hedberg.

The "calcareous members of the Aragua formation at Cerro Corazón" which Liddle (1946, p. 347) reported to carry "Venericardia planicosta Lamarck" belong actually in the Caratas formation. The species should be identified probably as Venericardia (Venericor) toasensis Dusenbury of Paleocene age (see appendix to Sutton, 1946, p. 1739-1741).

Leo Weingeist