CATATUMBO, Formation

UPPER CRETACEOUS ( ? )

Department of Santander del Norte, Colombia

Author of name: F. B. Notestein et al., 1944.

Original reference: F. B. Notestein et al., 1944, p 1186.

Original description: ibid.

The Catatumbo formation is the lowest part of the Orocué group of Notestein et al. (1944, p. 1186). It is named from the Río Catatumbo, along which the formation crops out between Barranca Bermeja and Puerto Salado, Barco concession, Colombia. The exposures along the river are not satisfactory as a type section, and therefore the section in well Oro N° 3, located 10 kilometers northeast of the type locality is used instead by Notestein et al. (1944, p. 1186).

The formation is predominantly composed of dark-gray shales and claystones, commonly somewhat carbonaceous and containing small nodules and thin lenses of brown clay-ironstone. In the Río de Oro area there is a considerable amount of interbedded and interlaminated gray and dark gray argillaceous, very fine to fine-grained sandstone, the beds ranging from 0.5 to 10 meters in thickness. Micaceous-carbonaceous laminae are common. Farther south, sandstones are much less common, and some well sections contain practically none. The percentage of claystones, characteristically containing more or less abundant siderite spherules, normally less than 1 millimeter in diameter, decreases from northwest to southeast, and the claystones are replaced by silty and sandy dark-gray shales. The formation commonly contains a few thin beds of coal, particularly in its lower part. Sandy sediments of the lowermost portion contain glauconite and rarely a few thin beds of nonglauconitic limestone. The associated shales are sparsely fossiliferous, containing arenaceous foraminifera, ostracods, and some large fossils.

The formation shows a considerable range in thickness. Well sections range from 106 to 208 meters in thickness; the thinner sections were logged on the Tibú and Sardinata anticlines. Surface sections measured on and adjacent to the Concession show 245 to 270 meters for the formation. It is at least 300 meters thick on the Río Pamplonita near Donjuana, south of the Concession, where the base of the formation is covered.

Production is obtained from sandstones in the Catatumbo on the Río de Oro and Sardinata anticlines, and many lenses and beds of sandstone show oil staining.

The lower boundary of the Catatumbo formation is at the top of the glauconitic limestone facies of the Mito Juan formation. The upper boundary is drawn at the base of the fairly continuous section of sandstones which constitute the Barco formation. Both boundaries are apparently conformable.

The age of the Catatumbo has not been definitely established, but there is good reason to think it may be upper Cretaceous, and it is being tentatively so classified. A sample of fossiliferous arenaceous shale, collected from the Catatumbo in the Puerto Salado area, was submitted to A. A. Olsson, who identified (personal communication) Venericardia sp., Mytilus or Modiolus, Calyptraea sp., Ostrea, possible young species of Exagyra, shell prisma (rare) of a pelecypod possibly Inoceramus, and echinoid plates and spines, the latter being very similar to spines found in a sample from the Río de Oro limestone facies of the Mito Juan formation. Concerning this marine fauna of the Catatumbo, Olsson states that without evidence to the contrary, he would be inclined to regard it as upper Cretaceous. Hedberg (personal communication) states that in his opinion, the fact that the "Ammobaculites" colombianus zone extends up from the Mito Juan into the lower part of the Catatumbo is further evidence that the Catatumbo is uppermost Cretaceous.

Except for its lower part, which is included in the "Ammobaculites" colombianus zone, the shales of the Catatumbo are characteristically barren of foraminifera. Presumably, much of the formation was laid down under brackish-water or nonmarine conditions.

The formation correlates directly with the lower part of the Third Coal formation of western Venezuela and with some of the uppermost Mito Juan as the top of that formation is, at least locally, drawn in western Venezuela.

According to Sutton (1946, p. 1656) the known occurrences of the Catatumbo formation are confined to the vicinity of the Barco concession in Colombia and to the contiguous portions of the states of Zulia and Táchira in Venezuela.

W. A. Mohler