BARRANQUIN Formation
CRETACEOUS (Neocomian? to Aptian)
State of Sucre, Venezuela
Author of name: R. A. Liddle, 1928.
Original reference: R. A. Liddle, 1928, p. 108, etc.
Original description: ibid.
The beds building up the area south of Cumaná, Cariaco, and El Pilar, Sucre, were correctly referred to the Cretaceous by H. Karsten (1850, p. 345). This region was designated by H. Karsten as "Ammoniten-Cebirge" (Karsten, 1850), by G. P. Wall as the "Older Parian System" of Neocomian age (Wall 1860, p. 460), and as "Kreidegebirge" by W. Sievers (Sievers, 1896, p. 236).
The outcrops of whitish-yellow, coarse-grained sandstones, limestones, and shales in the Cumaná-Manzanares area, Serrania del Interior, Sucre, were already mentioned by W. Sievers (1896, p. 260). This is the region of the village of Barranquín, lain between Cumaná and Río Manzanares, after which the Barranquín formation has been named and introduced into the literature by R. A. Liddle (Liddle, 1928, p. 108, etc.). W. Sievers, in 1896, correctly referred these sandstone beds below the Caripe limestone to the Lower Cretaceous. The sandstones exposed between Caripe and Aragua de Maturín, Monagas, and in the Bergantín area, Anzoátegui, which W. Sievers (1896) correlated with those cropping out near Barranquín, actually belong to younger formations (Chimana, Santa Anita formations).
R. A. Liddle gives the following description of the Barranquín formation: "...3500 to 4500 feet of quartzitic sandstone interbedded with highly arenaceous shale and an occasional limestone bed" . . . "the sandstones are buff, white, or reddish; and the main part of the shales is red, brown, pink, purple, tan, white, or black".... "Of the shales, which are interbedded with the sandstones, only relatively few are black on exposed surfaces; these are concretionary, arenaceous, micaceous, and pyritic. Limestones are rare, chiefly occurring near the top of the formation, generally partially metamorphosed, black to dark-gray, and full of calcite veins"..."The greatest known thickness of the limestone occurring in any single bed is less than 20 feet; often there are mere lenses, which have small lateral extent. The average thickness of these limestone beds is less than three feet. There are possibly 400 feet of limestone in the upper half of the Barranquín formation" (Liddle, 1928, p. 109-110).
This lithologic description was subsequently completed; H. D. Hedberg and A. Pyre report light-colored, reddish weathering, coarse-grained, cross- bedded, partly kaolinitic sandstones; shaly micaceous sandstone; plant-bearing carbonaceous shales; gray fossil-bearing sandy limestone with iron oxide content; bluish-gray reef limestone, with corals, rudistid mollusks, etc. (Hedberg and Pyre, 1944, p. 5; Hedberg, 1950, p. 1186).
The Barranquín formation is supposed to rest unconformably on the Caribbean metamorphics and is conformably superseded (transitional contact) by the reefal limestones and shales of the "El Cantil formation" of authors (see Borracha formation)
Because of structural complications, no continous sequence was hitherto measured, and the normal stratigraphic contact of the formation with the Caribbean schists has not yet been observed. The actual thickness of the Barranquín formation is, consequently, not known.
E. von der Osten (1953, 4, p. 133-139) subdivides the Barranquín formation into the following four members (from botton to top):
The Morro Blanco member, indicated to occur more than a thousand meters below the top of the formation (according to E. von der Osten), still carries Choffatella decipiens and Pseudocyclammina hedbergi, and limestones of the Picuda member contain Cuneolina (W. Maync, 1954).
The Barranquín formation crops out in the Coast Range of northeastern Venezuela (Sucre) and on some islands off the Cumaná-Barcelona coast (Anzoátegui). It is also reported from Lara (Segovia Highlands).
Fauna and Age. There are, as yet, no indications of the presence of truly marine sediments in the basal part of the formation, deposits which might correspond to the Barremian Pulchellia beds of Colombia and to the recently discovered Pulchellia beds (Barremian) of Trinidad (Kugler, 1953, p. 32-33). It is possible that these ammonite-bearing beds of Trinidad facially grade into the non-marine lower Barranquín formation of Venezuela.
Shales from near Santa María, Sucre, contain plant-remains (e.g., Weichselia mantelli) which suggest a Lower Cretaceous age. The coral faunas from the upper part of the Barranquín formation indicate an Urgo-Aptian age (Wells, 1944). The mollusk faunas recorded from Chimana Grande Island include Trigonia subcrenulata-tocaimaana, Tr. hondaana, Exagyra latissima (= E. couloni Defr. = E. aquila d'Orb.), Neithea quinquecostata var. morrisi, etc.; these species are not restricted to a certain stage but characterize beds of Valanginian to Aptian age (Royo y Gómez, 1953). The occurrence of ?Deshayesites and Nechibolites semicanaliculatus? (Blainv.), found (in situ.) in the Barranquín Formation of Chimana Grande Island (Royo y Gómez, 1953, p. 136), would indicate a post-Barremian age. The microfauna, with Choffatella decipiens Schlumberger, Pseudocyclammina hedbergi Maync, Textularia rioensis Carsey Cristellaria ex gr. gaultina Berthelin, etc., encountered in marine levels of the Barranquín formation, is held to be early Aptian in age (Rod and Maync, 1954, p. 262-263); the lowermost part probably is of Barremian age.
In Eastern Venezuela, the Aptian Choffatella biozone extends from the upper Barranquín formation up to the top of the Borracha formation (Rod and Maync, 1954, p. 262, 277); in Western Venezuela, it coincides with the Apón formation (Maync, 1949 (1950) ).
Wolf Maync
BORRACHA Formation
CRETACEOUS (Aptian )
State of Anzoátegui, Venezuela
Author of name: E. Rod, 1952 (private report).
Original reference: E. Rod and W. Maync, 1954, p. 228, etc.
Original description: ibid.
The name Borracha formation, first used by E. Rod in 1952 (Company Report) for the thick limestone complex overlying the Barranquín formation on La Borracha Island, Anzoátegui, was published in 1954 (Rod and Maync, 1954, p. 228 etc.)
The Borracha formation includes the reefal limestone unit formerly referred to the lower part of the El Cantil formation of authors (Liddle, 1928, p. 134).
R. A. Liddle mentions the El Cantil limestone of La Borracha Island without giving a lithologic description (loc. cit.). H. D. Hedberg and A. Pyre stress the bioherm character of the bluish gray massive El Cantil lime- stone which shows a transitional contact with the Barranquín and Chimana formations. A lateral facies change of this El Cantil limestone into the glauconitic sandstones and shales of the Chimana formation is also observed (Hedberg and Pyre, 1944, p. 8).
E. Rod's name, Borracha formation, taken from La Borracha Island, is applied to the variety of zoogenic limestones with interbeds of varicolored shales and marls which occur between the Barranquín formation and the overlying Chimana formation (Rod and Maync, 1946, p. 228, etc.). A conspicuous body of shales and marls within the biostromal limestones readily allows a subdivision of the Borracha formation into an upper, middle, and lower Borracha member. Tne term García member is also applied to the middle Borracha member.
3.- Upper Borracha member.
At the type locality on La Borracha Island, the upper Borracha member is exclusively composed of massive, dark to blue-gray, coquinoid dense or sub-oolitic limestones, sometimes with sideritic infiltrations; coral-bearing and algal limestones; subordinate interbeds of shale and sandstone. Thickness: ?60 to 225 meters (Rod and Maync, 1954, p. 241). Microfauna: Choffatella decipiens Schlumberger, Spiroplectammina goodlandana Lalicker, Textularia rioensis Carsey, etc. Orbitolina concava-texana (Roem.) is rarely found below the Chimana formation (e.g. in the Guariquén section, eastern Sucre). The upper Borracha member is conformable with the subjacent García member; a disconformable (in places unconformable) contact exists with the overlying Chimana formation.
2.- García member (middle Borracha member)
At the type locality (eastern slope of Pico García, north of Aragua de Maturín, Monagas), dark gray to ocre marls with some nodular marry limestone occur at the base. On La Borracha Island, a basal sandstone layer with lenses of coquinoid limestone was observed; higher up in the section appear gray, often marry, varicolored shales, shelly limestone, oyster-bearing sandstone, ironstone seams; shales and sandy shales at the top.
Thickness: 50-105 meters (Rod and Maync, 1954, p. 235).
Fauna: A rich ammonite fauna, collected in 1922 by M. Reinhard at Pico García and described by L. W. Collet, includes typical upper Aptian genera, such as Colombiceras, Dufrenoya, Cheloniceras, etc.; a lower Aptian age is suggested by the occurrence of several species of Deshayesites (see faunal lists in Collet, 1922, p. 16-17; in Rod and Maync, 1954, p. 264-265). The microfauna contains Choffatella decipiens Schlumberger, Ammobaculites subsecretaccus Cush. & Alex. Forms like Cristellaria ex gr. gaultina Berth., Epistomina cf. colomi Sigal, Textularia rioensis Carsey, etc., were also found in other Lower Cretaceous formations.
The García member is conformable with the upper Borracha member; the contact with the lower Borracha member appears to be disconformable, on La Borracha Island even unconformable.
1.- Lower Borracha member.
This member consists of dark-gray massive, crystalline, sometimes oolitic, zoögenic limestones which develop into coarse conglomeratic coquinas; often with sideritic infiltrations and pyrite (Las Cinco Ceibas type); rudistid and coral-bearing limestones, Nerinea limestones, Miliolid limestone, Cuneolina limestone, etc. At the top of the lower Borracha member, a shell-bank limestone is often developed, and rare sandstone beds occur locally in the lower part. Thickness: 10-150 meters (Rod and Maync, 1954, p. 235). Microfossils: Choffatella decipiens Schlumberger, Pseudocyclammina hedbergi Maync, etc.
The lower Borracha member is transitional with the underlying Barranquín Formation, and apparently conformable (?disconformable) with the middle Borracha member above; on La Borracha Island, however, the upper boundary represents an unconformity.
Age of the Borracha formation:
The prolific ammonite faunas of the García member are reported to captain genera and species of both upper and lower Aptian age.
The Choffatella biozone of Aptian age includes the interval Barranquín formation to top of Borracha formation. In Western Venezuela, it is represented by the Apón formation. (Maync, 1949 (1950); Rod and Maync 1954).
Wolf Manyc