SANTA BARBARA, Facies

CRETACEOUS

State of Barinas, Venezuela

Author of name: L. Kehrer, 1938.

Original reference: L. Kehrer, 1938, p. 49.

Original description: L. Kehrer, 1937, p. 66.

The Santa Bárbara facies as defined by Kehrer (1938, p. 49) is part of a general facies differentiation of the Cretaceous along the southeastern Venezuelan Andean mountain front from Santo Domingo, State of Táchira, to the Quebrada or Río Quiu (El Mene), State of Barinas. Over this distance of 280 kilometers, Kehrer (1938, p. 49) defines four facies types: 1) the Ortiza facies (predominantly limy) (to the west near Santo Domingo); 2) the Navay facies (predominantly cherty-clayey) (named from outcrops on the Río Navay); 3) the Santa Bárbara facies (predominantly chertysandy) (named from the town of Santa Bárbara); and 4) the Quiu facies (predominantly sandy-clayey) (named after the Río El Mene or Qulu). Kehrer (1938, p. 49) states: "these facies changes comprise the strata from Colon shales to and including Luna-Cogollo limestone. Between the diferent facies types exist transitions. There is no doubt about the Cretaceous age of Ortiza facies (Colon shales, Luna-Cogollo limestones). The Cretaceous age of the transition to the Navay facies is established by a limestone bank with typical Exagyra of the Cogollo limestone and the fair amount of fish-remains in the interbedded clay and chert beds. The Quiu facies is proven as Cretaceous (Turonian) by fossil evidence determined by Woodring. The thicknesses of upper-middle Cretaceous sediments are increasing towards the east and reach about 1,700 meters in the Santa Bárbara area".

"It is considered possible that the distribution of these facies types depends on the situation of old basement ridges. These different facies types seem to be shallow water deposits. In spite of the fact that they look rather different, they have a few characteristics in common such as good stratification, numerous fish-remains, cherts and limestone beds."

"This part of the Cretaceous in the South Andean area is very similar to the corresponding Cretaceous in the Bogotá area, viz., the Guadalupe series (Turonian?) consisting there also of sandstones, cherts, clays and fishbone beds."

Kehrer (1937, p. 66) had previously discussed these Cretaceous beds in general terms without naming the various facies such as the Santa Bárbara. He mentioned that: "To the south of the Andean watershed between La Palmita (southeast of San Cristóbal) and the region of Santa Bárbara, State of Barinas, the Cretaceous seems to be developed in a somewhat different facies. The black chert horizon which reaches a thickness of 40-50 meters in northern and western Táchira becomes considerably thicker. The cherts have whitish-gray colour; siliceous shales and sandy shales with much vegetable matter are interbedded, the limestone banks of La Luna and Cogollo have practically disappeared and dark shales and micaceous slates occupy their places above the Tomón sandstone. This modified chert horizon contains a fair amount of fish remains, viz., scales, teeth and vertebra. In certain cases we may even speak of a fish bone-bed. Shales sometimes carry Orthokarstenia ewoldi Karst, and undetermined bryozoa."

The writer would take exception to the thickness of 1,700 meters of upper-middle Cretaceous sediments in the Santa Bárbara area as given by Kehrer (1938, p. 49). It would appear that Kehrer did not recognize the reworked nature of much of this section as pointed out by Liddle (1946, p. 532-33).

(See also SANTA BARBARA "SERIES" and SANTA BARBARA DE "ZAMORA" BEDS.)

H. Alberding

SANTA BARBARA, "Series"

TERTIARY (upper Oligocene or lower Miocene)

State of Zulia, Venezuela

Synonym of LA ROSA FORMATION

Author of name: R. A. Liddle, 1946.

Original reference: R. A. Liddle, 1946, p. 453.

Original description: none.

Liddle (1946, p. 453) observed that: "Some geologists refer to the section as La Rosa formation; some refer to it as Lower La Rosa or Santa Bárbara series, reserving the Upper La Rosa series for beds which are referred to by others as Lagunillas formation."

See LA ROSA FORMATION for further discussion