CALDERAS, Formation

LOWER CRETACEOUS

State of Barinas, Venezuela

Author of name: R. L. Collins.

Original reference: A. N. Meckenzie, 1937, p. 260.

Original description: ibid.

The name of Calderas formation was given by R. L. Collins to a conglomerate at the base of the Cretaceous in the Barinas area. The formation is typically exposed at the Río Calderas canyon, where it crosses the Río Calderas canyon, where it crosses the Cerro Azul range, 8,5 Km. southeast of the village of Calderas.

The Calderas formation consists of fine to coarse calcareous conglomerate interbedded with fine to coarse sandstone. The general color is light gray. The lower part contains angular fragments up to 10 cm. It is massive, with cross bedding in places; very hard, indurated, and resistant to erosion. It contains fragments of oysters and is a typically basal deposit. The thickness varies from 10 to 150 meters.

The Calderas lies unconformably over the Cerro Azul formation and on the Río Masparro formation to the north. It underlies the Cogollo formation or El Cantíl formation with a contact that is sharp and apparently conformable.

Mackenzie (1937, p. 260) gives the age as "Basal" or Lower Cretaceous. This age has not been definitely established and cannot be, until be overlying section has been detailed.

Ivan A. Koves