SABANETA, Formation

PALEOZOIC (Devonian? - Lower Carboniferous ?)

State of Mérida, Venezuela

Author of name: Unknown.

Original references: E. Kündig, 1938, p. 28; L. Kehrer, 1938, p. 53.

Original description: ibid.

The name "Sabaneta group", for Paleozoic beds, was published simultaneously in 1938 by two geologists of the Caribbean Petroleum Co., E. Kündig and L. Kehrer. The reference by Kündig has page priority, but on the other hand, the locality mentioned is not what has subsequently been stated to be the type locality; Kehrer's description apparently does refer to the type. Since both geologists were associated with the same company, and Kehrer was the senior geologist, is seems convenient to consider the two as joint authors.

The type locality (not specified in the original references, but given on Kehrer's authority by González de Juana, 1951) is Sabaneta in southeastern Mérida (Distrito Libertad). This is in the region of the section across the Andes from Mucuchací to Santa Bárbara de Barinas, published by Christ (1927); the reader is referred to the article on the "Sabaneta group" of Oppenheim (1937) for the background of previous work and general geology, necessary to understand what is left unsaid in the original references to the Paleozoic Sabaneta. As we stated there, the "Mucupatí group" of Christ included both beds stratigraphically below the Permocarboniferous Palmarito "group", and much younger Cretaceous beds in fault contact with the pre-Palmarito. This fault is shown on Kehrer's geologic map of the southern Andes (1938), but since (1) the Palmarito and the Paleozoic Sabaneta are not differentiated on the map; (2) Christ's confusion with the Mucupatí is not brought out, and finally (3) neither Kündig nor Kehrer makes any reference to the paper by Oppenheim (1937) and his use of the "Sabaneta" for Cretaceous beds, their discussions are somewhat unsatisfactory.

Kündig, for instance, introduces the term "Sabaneta" in a section headed "Mucupatí group: Middle to Upper Devonian". After some inconclusive remarks about the Mucupatí, including that Kehrer thinks it might be Cretaceous, Kündig goes on to say:

. . . "In the highway from Páramo de Zumbador to Queniquea, in a highly disturbed region, there outcrops, possibly below the Carboniferous Palmarito group, a group of quartzitic sandstones, extremely hard and thickbedded, of greenish to reddish color (called unofficially the Sabaneta group) which has been considered as upper Devonian or Lower Carboniferous. They show no signs of metamorphism, and the contact with the overlying Carboniferous seems to be, as far as can be seen, transitional." (Kündig, 1938, p. 29).

Kehrer introduces the term after a description of the Palmarito "group"; the fact that he mentions that a good section of the Palmarito is exposed between Palmarito and Sabaneta, and that the description of the Sabaneta immediately follows that of the Palmarito, is the only indication that the name "Sabaneta" is derived from this region:

"Below the fossiliferous shales and limestones of Permian and Upper Carboniferous age . . . there appears a body of hard sandstones and shales of reddish or greenish color, the Sabaneta group which in places greatly resembles the red beds of the La Quinta (Gir¢n) formation. However, their position is undoubtedly below the Palmarito limestone. Plant remains are very frequent. Possibly they may be compared with the Pipital" (misspelled Piripital in the Spanish text) "beds which occur below the Carboniferous in the Quetame massif between Bogotá and Villavicencio, in Colombia. Their age is not known with certainty, but it is assumed that they could represent Lower Carboniferous" (Kehrer, 1938, p. 53-54).

These descriptions were quoted by Liddle (1946, p. 124-125) under the general heading of "Palmarito series". Liddle incorrectly refers to the Sabaneta "series". Sutton (1946, p. 1646) mentions Oppenheim's Cretaceous Sabaneta, but not the Paleozoic formation of Kündig and Kehrer, which we presume is included in his Palmarito.

The ambiguities and deficiencies of the original descriptions were remedied to a considerable extent by González de Juana (1951), who had access to a private report by Kehrer. The following data, therefore, taken from González de Juana's paper, may be taken to represent Kehrer's understanding of the Sabaneta.

The type locality of the Sabaneta (called "formation" by González de Juana, instead of the incorrect original designation of "group") is, as mentioned above, specified as being Sabaneta, some 3 kilometers southeast of La Aguada, and a geological section showing the relations of the La Quinta, Palmarito and Sabaneta formations is included (González de Juana, 1951, fig. 5). The Sabaneta is described as consisting of sandstones and sandy shales, frequently micaceous, of reddish and greenish colors, with some conglomeratic intervals, lithologically similar to the La Quinta beds but distinguished by somewhat darker red color tending to wine-red, by the slaty character of the shales, and by the different origin of the components of the conglomerates. Reddish colors are said to predominate in the upper part of the formation, while towards the base there are deeper tints and greenish shades. The thickness is between 500 and 600 meters. The Sabaneta is said to lie on the metamorphic rocks of the Mucuchachi, with an apparently transitional contact, and to be transitional above with the Palmarito formation.

In addition to the type region, and the exposures already mentioned by Kündig (Zumbador-Queniquea in Táchira), the Sabaneta is reported to occur on both sides of the La Negra pass; on the road from Timotes to La Puerta (Trujillo), where it contains some thin coal beds with plant fossils; on the road from La Cuchilla to Carache, and in the "alto" of Bolivia. In addition, since the Mérida formation of Kundig (1938) is said to have been proved exactly equivalent to the Sabaneta, the latter must be said to outcrop near the city of Mérida. On the east front of the Perijá range, Liddle (1946) does not mention it, but González de Juana considers that the lower, red part of Liddle's "Palmarito" on Río Cachirí, should be referred to the Sabaneta. (riddle's mention of a basal conglomerate with limestone pebbles, suggests to the undersigned that these beds might be La Quinta, but Liddle lays stress on the absence of fusulinids in this limestone, so that the correlation with the Sabaneta may be justified.)

Bucher (1952, p. 13) calls the Sabaneta "Late Devonian or early Mississippian" and states that in his geologic-tectonic map of Venezuela, it has been included under the symbol for Devonian (De). (However, in the type region, the area he maps as "Permo-Carboniferous" presumably includes the Sabaneta.)

Nothing has been published about fossils from the Sabaneta. González de Juana (1951, p. 133) reports having collected some gastropods from the formation, on the highway between Timotes and La Puerta, but there is no information available. The only grounds for deducing the age are, the stratigraphic position, and the reported frequency of plant remains, which in itself suggests that the formation is not likely to be older than, say, upper Devonian. As regards the reported transitional relations with the Mucuchachí (itself of undetermined age, Cambro-Ordovician in the opinion of Sutton, Devonian according to Kehrer and González de Juana) and with the Palmarito above, the undersigned frankly doubts that both (if indeed either) of these contacts have been adequately investigated. Considering the highly disturbed nature of the region, the contact with the Mucuchachí might be difficult to determine or interpret; while as regards the supposed transition with the Palmarito, there is some evidence to the contrary. Christ (1927) himself thought that there was an angular discordance of about 15ø between the Palmarito and his "Mucupatí" (in that place, Sabaneta) in the vicinity of Palo Quemado. He states (we quote without page reference, since the paper is available to us only in a private translation):

..."150 or 200 meters N. W. of the house "(Palo Quemado)" there are sandy clays of a reddish or brownish color, the dip of which is about 45°NW, while the Trilobite clays "(Palmarito)" dipped only about 20 to 25°".

Bucher (1952, p. 15) also quotes Schürmann (1939, p. 25) to the effect that near El Cobre, Permo-Carboniferous limestones lie unconformably on strongly folded, red and green unfossiliferous shales. Bucher suggests that this unconformity may indicate a "Variscan", pre-Permocarboniferous orogeny.

Without going so far as to consider this definitely proved, we would remark that the lower age-limit of the Palmarito has not yet been determined, and we believe (as mentioned in our article on the Palmarito) that the formation may be of different ages in different places. Reworking of earlier red continental beds by a transgressing Palmarito sea, might give rise to an apparent transitional contact. On the other hand, it is possible that the contact really is transitional (at least in places), which would mean that the Sabaneta might be somewhat younger than generally supposed (Pennsylvanian or even early Permian). -Or again, it is possible that red formations of more than one age have been included in the Sabaneta, (i. e. the beds at El Cobre may be older than the type Sabaneta at Sabaneta. ) What seems to us definitely not probable, is that one formation could represent all the interval from perhaps Pennsylvanian down to upper Devonian or perhaps even older (depending on the age of the Mucuchachí). The solution of these problems will have to be left to future researches. Study of the Sabaneta fossils could be the first step of their solution.

Frances de Rivero