CAMPO CHICO, Formation

MIDDLE UPPER DEVONIAM

State of Zulia, Venezuela

Author of name: R. A. Liddle, et al., 1943.

Original reference: R. A. Liddle, et al., 1943, p. 19-21.

Original description: ibid.

The Campo Chico formation is the uppermost unit of the Río Cachirí group. Its type section is in Caño Grande, a tributary of the Río Cachirí in western Maracaibo District about 88 kilometers west of the city of Maracaibo. In Caño Grande, the Campo Chico formation extends from a point 1,400 meters downstream to a point 2,065 meters downstream from the junction of Caño del Sur. The formation is said to be conformable and transitional with the underlying Caño del Oeste formation, and unconformable, though virtually accordant, with the overlying Palmarito formation of Carboniferous-Permian age. It is not possible in the type section to determine with certainty, but the unconformity between the Campo Chico and Palmarito formations is believed to be one of considerable magnitude because of the absence of section between the top of the Campo Chico formation and the conglomerate at the base of the Palmarito formation.

The Campo Chico formation is at least 609 meters (2,000 feet) thick in the type section where it consists of dark gray, evenly bedded, ferruginous quartzitic sandstones interbedded with hard dark gray, micaceous and sandy shales. There are also a few thin black limestones. In Caño del Oeste, about 2 kilometers northeast of Caño Grande, quartzites with rounded to angular grains of quartz are present in the formation, and in Caño del Norte, about 3.8 kilometers northeast of Caño Grande, dense dark gray sandy limestones and calcareous sandstones are components of the formation. No fossils are reported from the Campo Chico formation but its conformability with the underlying Cañoo del Oeste formation of Middle Devonian age and the resemblance of some of the strata of the two formations, suggests to the present writer that the age of the Campo Chico formation is Middle-Upper Devonian.

The Campo Chico formation has been mapped for a distance of 4 kilometers between Caño Grande and Caño del Norte. It undoubtedly continues northward from Caño del Norte and southward from Caño Grande, but the distances are not known. Liddle, et al., (1943, p. 20) infer that the Río Macoita formation is equivalent to the Campo Chico formation and state the Río Macoita formation, or remnants of it, is exposed in Rios La Gé, Tinacoa and Macoita in the District of Perijá  southwest of Caño Grande. Based on this correlation, the Campo Chico formation and its counterpart, the Río Macoita formation, is present in a belt along the east flank of the Sierra de Perijá for a distance of at least 70 kilometers.

Norman E. Weisbord