LA QUINTA, Formation
UPPER TRIASSIC and JURASSIC
State of Táchira, Venezuela
Author of name: E. Kündig, 1938.
Original reference: E. Kündig, 1938, p. 31, 32.
Original reference: ibid.
The name, La Quinta "series" (in the Spanish edition, "formación") was published by E. Kündig (1938, p. 31, 32) to designate predominantly redcolored non-marine, clastic beds of lower Mesozoic age, extensively distributed in the Venezuelan Andes. While Kündig's name is by no means the first that had been proposed for this formation, his designation of an excellent and accessible type section, and his complete description (including the first report of fossils) have led to the general adoption of his name, in preference to earlier but less well defined ones (Lagunillas conglomerate of Sievers, 1888; Lomita series of P. Christ, 1927; Old Red series of Liddle, 1928, Red formation of Oppenheim, 1937, and others to be mentioned.)
These red clastic sediments had long been observed both in Venezuela and Colombia, but until around 1938 they were not always clearly distinguished from basal Cretaceous sandy beds which generally overlie them, often without apparent unconformity. Thus the "Lagunillas conglomerate" of Sievers (1888, p. 8-16) included basal Cretaceous conglomerates in places (according to Gerth, 1935, p. 221; Sutton, 1946, p. 1637). In addition, the type locality is not considered satisfactory, so the name is not at present in use. It was mentioned by Engleman (1935), Schuchert (1935), Gerth (1935) and Liddle (1928); but since the publication of Kündig's name, the only author who has attempted to revive the name Lagunillas seems to be Rutten (1940, 1942). Even if the name were better defined, any attempt to revive it would be inconvenient on account of the well established use for a Tertiary formation of the Maracaibo basin (see LAGUNILLAS Formation). The term "Lomita series" of P. Christ (1927) is a prior synonym, as modern authors (Sutton, 1946, p. 1639; González de Juana, 1951, p. 196) have recognized, but they have not attempted to substitute it for Kündig's better defined name.
The term "Old Red series" of Liddle (1928, p. 101-104), although in general use in Venezuela between 1928-1938, is entirely undesirable as a nongeographic term; in addition, Liddle (1946, p. 124) admits that it included some older beds. The same objections hold for Oppenheim's (1937) "Red Formation". (See "OLD RED Series" and RED Formation.)
R. Englemann (1935, p. 780-783) gave an interesting discussion of "PermoTrias? Red-beds" in the Andes; he suggested that the beds were equivalent to the "Jiron" (Giron) of Colombia, and also suggested a possible correlation with the Roraima beds of the Gran Sabana. He noted the occurrence of cobbles of Paleozoic limestone in the basal red-beds near Mucuchachí; a possible discordance between the red-beds and Cretaceous sandstones in Río Canaguá (or Libertad); and states that the Red-beds outcrop northwest of Maracaibo, where locally they have been called the "Peñocira" (only published reference to this name). He also reports that the Red-beds had been cored in wells some 20 km. SE of the outcrop in Manantiales, lying normally below the Cretaceous.
H. Gerth (1935, p. 221-223) has section on "terrestrial deposits of probably Triassic age in the northern Cordillera", in which he uses the term "intermediate beds" ("Zwischenschichten") to designate the red-beds, with reference to their position between Paleozoic basement rocks in the Serranías of Mérida and Perijá and the overlying Cretaceous. He recapitulates the work of Sievers, Christ and Liddle, stressing Sievers's (1888) description of the red-beds on the Colombian side of the Perijá range, which brought out that these rocks overlie tuffs, breccias and flows of quartz-porphyry and melaphyre, and have similar volcanics intercalated in them. On account of the similarity to beds referred in Argentina to the Triassic (Paganzo series), Gerth believes the red-beds to be Triassic. - The "Jiron beds" of Colombia, however refers tu the Cretaceous (p. 352).
The name Girón (often spelled Jirón), first applied by Hettner (1892) to beds near the town of that name in Colombia, Department of Santander, is the only term that has offered serious competition to the name La Quinta. Schuchert (1935, p. 670), in connection with the Girón group of Colombia, states that it is represented in Venezuela by "the Lagunillas conglomerate of Sievers, the Palmarito and Lomita of Christ, and the Old Red series of Liddle". On p. 689, he quotes Stappenbeck (1927) (a publication we have not seen) as considering the Girón to be represented by the Lagunillas conglomerate. Schuchert reflects accurately the contemporary uncertainty on the age and correlation of the Colombian Girón, noting that some geologists correlate it with the Villeta group (Cretaceous), others believe it older Mesozoic or possibly even Paleozoic. This uncertainty is also reflected by Schuchert's mention (1935, p. 689) of the Lagunillas conglomerate under his discussion of the Lower Cretaceous in Venezuela.
L. Kehrer (1937, fig. 1) used the term Girón, and gives reasons for preferring the name to Lagunillas or Old Red (p. 55). Although in his 1938 paper he uses the designation "La Quinta (Girón)" throughout, in the discussions of the papers presented at the 1938 Venezuelan Geologic Congress, he states that he would prefer to retain Girón rather than introduce a new name (p. 240).
It is fortunate for Venezuelan geologists that the name La Quinta has replaced Girón, since the latter has had a long and tangled history in literature. (See for instance Oppenheim, 1940). Although various authors have separated Cretaceous beds from the Girón, apparently it is still not very well defined, as brought out by the recent discovery of Carboniferous and Permian fossils in part of the Girón by Brückner (1954).
A few others synonyms of the La Quinta formation should be mentioned: The Río Masparro formation of Mackenzie (1937, p. 276) (see article). Hedberg and Sass (1937, p. 75) proposed the name Macoita formation for red beds "well exposed in the Macoita River" and which had been referred to the "Old Red series"; however, Liddle (1946, p. 118) states that within the section mentioned by these authors, there are no beds which had been referred to the "Old Red", but only shales and sandstones of the Devonian Campo Chico formation (See article MACOITA Formation). The Seco conglomerate of Sutton (1946, p. 1639) is also a synonym of the La Quinta formation (see article).
The term "Formación La Quinta" (in the English edition, La Quinta series) was given by Kündig in allusion to the small town of La Quinta, about 3.5 kilometers west of La Grita in Táchira. The type section is exposed along a road which, leaving the Trans-Andean Highway near La Quinta (elevation 1,130 m.), leads to the town of Seburuco, 7 km. distant. Following this road downstream along the La Grita river, a section of the La Quinta formation, some 2,300 meters thick in total, is exposed, the beds resting with strong angular unconformity on phyllites and "epi-schists" referred to the Mucuchachí formation. The Mucuchachí beds dip 30-50° SE, while the La Quinta dips 60-70° WNW. The La Quinta section can be divided here into a lower conglomeratic portion (400 m), a middle predominantly shaly portion, (500 m.) and an upper sandy portion (1,300 m.) The beds are overlain by white sandstones of the "Tomón" (Cretaceous) with apparent conformity. Kündig's detailed description of the three divisions (which are not suggested to be formal members) is as follows:
Lower division: Conglomerates, dark (greenish) red, hard, poorly sorted, with pebbles up to fist-size, well rounded and strongly cemented. Some finer-grained beds "contain tuffaceous material and especially much biotite". The conglomerates are interstratified with brick-red, soft, heavy bedded clayey sandstones. Total, 400 m.
Middle division (exposed near the bridge of La Grita), begins with the following detailed section:
a) 5 m. dark red and greenish shales.
b) 2 m. conglomeratic sandstones, cross bedded, white, redstained, has pebbles of quartz only.
c) 10 m., like (a), on top of red sandy shales.
d) 1 meter bed, like (b).
e) 4 meters red shales, which contain in the upper part fish scales and bones, and greenish-white coprolites.
f) 1 meter bed like (b), but red in color.
g) 5 m. micaceous sandy shales with scattered fish-remains.
h) 2 m., like (b).
A repetition of similar beds (except that the white conglomeratic beds disappear) occurs for 150 meters or more; Kündig estimates the total thickness as 500 meters. A talus zone marks an interval, then there follows the upper division, of well-stratified, soft red cross-bedded sandstones, interbedded (in a narrow zone) with a hard white coarse quartz sandstone. This upper sandy division is said to be 1,300 meters thick.
The fish remains found in horizons (e) and (g) were studied by A. Smith Woodward, who determined them as consisting of plates, premaxillas, teeth, palatal bones and scales "of a genus of fish indistinguishable from the genus Lepidotus". (For the systematic classification of this fish, see Romer, 1945, p. 97, 580). Romer gives the geologic range of Lepidotus as Upper Triassic to Lower Cretaceous, perhaps even Upper Cretaceous in Europe. Woodward believed the remains to indicate a rather primitive form of the genus which would suggest an age of Upper Triassic or Lower Jurassic.
From Romer's discussion (1945, p. 537) it would appear that Lepidotus was a marine denizen (although he notes that little is known of fresh-water fish of the lower Mesozoic). However, Dr. Royo y Gómez informs us that the genus has also been found in brackish and fresh-water sediments. It was suggested in Kündig's paper that the coprolites associated with the fish remains were formed by sharks. There is thus a suggestion of a marine environments for the fish-bearing beds, but the evidence is by no means conclusive. Kündig did not discuss the problem. One might speculate on the possibility of a marginal marine incursion from a sea normally far to the west; such an incursion, perhaps, as suggested by the marine fossiliferous horizon in the predominantly red Payand formation of Colombia (see Trumpy, 1943). On this supposition, Kehrer's report (1938) of an unidentified ammonite and a Halobia ? from supposed "Mucuchachí" beds, which as Sutton (1946, p. 1638) suggested, might really be La Quinta, could fit into the picture.
A different, non-marine, environment is indicated by the fossils cited by Sutton (1946, p. 1638), found in black shales in the La Quinta formation in the state of Mérida. These fossils were found by Olsson and Dallmus, along the trail from Potosí to Canaguá near the Hacienda Montaña, at a locality called Celensio. Olsson identified the fossils as fresh-water ostracods, and abundant specimens of the conchostracan phyllopod Estheria. (In the recent text of Moore, Lalicker and Fischer, the name of this genus is changed to Cyzicus). This genus is fairly common as a fossil in fresh and brackishwater sediments from the Devonian onward, but Olsson considered the Celensio specimens to be most similar to species found in Upper Triassic formations of India, Argentina and Colombia.
The La Quinta formation has an extensive but somewhat irregular distribution in the Venezuelan Andes, and has been recognized in limited areas, on the east flank of the Sierra de Perijá. In the Andes, it occurs on the southwest flank, towards the Táchira depression, and in southeast Mérida; but it appears to be missing over the central, highest part of the Cordillera, as pointed out by González de Juana (1951, p. 196) and Bucher (1952, p. 15). The latter notes that two lines on the map, one from Ciudad Bolivia to Mérida, the other from Barinas to Valera, delimit a belt at right angles to the present Andean axis, where La Quinta sediments are missing. These authors believe, therefore, that this belt represents an old Paleozoic uplift and that the continental sediments of the La Quinta were accumulated principally on the flanks of this uplift. With reference to this apparent absence of La Quinta in the Andean knot, however, it may be mentioned that according to Sievers, 1888 (as quoted by Engleman, 1935, p. 783) almost all the crest of the Sierra Culata or Sierra del Norte near Mérida, is made up of "red-beds". Engleman did not visit this region, but states that "his experience with Sievers's judgement in other parts of the mountains" inclines him to believe that this might be so. The undersigned does not know whether sufficiently detailed studies have been since made in this region, to disprove Sievers' findings.
Northeast of this belt, the La Quinta sediments again appear on the flanks of the Andes. Bucher's map shows an irregularly V-shaped belt which appears to follow the general line of the Mucuchachí outcrops near Ciudad Trujillo. On the opposite or southern flank the beds are brought to the surface in anticlines in western Portuguesa and Barinas (see Bucher's map, south center of quadrangle D: 9-10°).
Liddle (1946, p. 141) states that "the most northeasterly outcrop of definitely known La Quinta series is in the southwestern part of the State of Lara" and that "it is possible that partly metamorphosed shales and slates around Quibor in the south-central part of the State of Lara were derived from sediments of La Quinta series rather than from the Barranquín formation." No La Quinta is shown in Lara on Bucher's map, however.
The possibility that La Quinta sediments might exist or have existed far to the north of the present outcrops, however, is suggested by the presence of red-beds in a well (Manuel N° 1) in the represent La Quinta. (S. E. Aguerrevere, 1938, p. 250). Hedberg (1942, p. 201) has also suggested the possible equivalence of the Hato Viejo-Carrizal formations of the subsurface in Guárico-Anzoátegui. The thickness of the La Quinta formation in the Andes is said to be extremely variable, with the figure of 3,600 meters reported by Kündig for the section in El Zumbador, as a probable maximum. It should be noted that in some places (e.g. near Trujillo, as reported by Schaub, 1944) the base of the La Quinta is a conglomerate formed by pebbles of the Palmarito formation.
In the Sierra de Perijá, the La Quinta is considered to be represented by the "Seco conglomerate" (Sutton, 1946, p. 1639), found in the quebrada Aponcito Seco, NW of Machiques, where it is some 670 meters thick. (See SECO Conglomerate). Similar conglomerates are reported towards the south in the Macoíta river, where La Quinta beds are said to overlie the upper Devonian (?) Macoíta formation, with unconformity that is not readily apparent (see MACOITA Formation). Towards the north, however, the La Quinta seems to disappear; at least, Liddle did not recognize it in the Río Cachirí section (Liddle, 1943, 1946). González de Juana (1951, p. 196) reports that it outcrops northwest of Maracaibo, in the Manantiales ridge (this is shown in Bucher's map.) The same author believes that red beds occurring on Toas island, referred by Sutton (1946) to the "Palmarito", are more probably La Quinta.
Hedberg (1942, p. 197-200), in an interesting discussion of the La Quinta-Girdn beds of Colombia and Venezuela, notes that the contact between these and overlying basal beds of the Cretaceous frequently appears to be transitional, but that in some cases there is visible unconformity; he believes that this indicates weak orogenic movements that followed the deposition of the La Quinta beds and preceded the Cretaceous transgression. Bucher (1952, p. 16) agrees with this interpretation. Hedberg believed that this orogenesis occureed in late Jurassic time, but Bucher does not commit himself to a definite date.
Kündig (1938) reported that basic igneous intrusions, in the form of small lenses and sills up to 80 meters thick, are locally developed in the La Quinta formation (e.g., west of Mérida in the Carvajal valley and north of Lagunillas in the valley of Aguadura). Petrographic types represented are porphyritic diabases, porphyritic quartz-diorites and vitriophyric diabases. The rocks are believed to be in part superficial flows, in part intrusions. There is no indication of metamorphism, and the intrusions (at least in the region of Mérida) do not affect younger rocks.
Frances de Rivero
TERTIARY (lower-middle Miocene)
State of Zulia, Venezuela
Authors of name: H. D. Hedberg and L. C. Sass, 1937.
Original reference: H. D. Hedberg and L. C. Sass, 1937, p. 100.
Original description: ibid.
The name Lagunillas formation refers to one of the major Miocene subsurface divisions of the Bolívar Coastal field and is derived from the village and oil field of Lagunillas in the Bolívar District, State of Zulia. The formation here consists of about 300 meters of light gray, light green and whitish sandstone, siltstones and shales, and interlaminated sandstone and shale. There are some mottled claystones in the upper part. Lignites are fairly common and a glauconite zone as much as 30 meters in thickness occurs in the lower part of the formation. According to Sutton (1946, p. 1688) the basal 100 to 150 meters of the formation in the Bolívar Coastal field is known as the Lower Lagunillas Sand, the top of which is usually fixed by the first appearance of shales with sand laminations. In the Lagunillas area the zone on top of the Lower Lagunillas Sand thickens, especially the sands which locally become predominant and are called the Upper Lagunillas Sand. The Lagunillas formation is also well represented in well sections in the district of Urdaneta on the west side of the Lake Maracaibo. The discussions of Hedberg given below are strictly limited to these occurrences. On the west side of the lake the formation thickens rapidly from 350-450 meters near the lake shore to as much as 900 meters in the central part of the district of Urdaneta, State of Zulia, where it grades laterally into the Los Ranchos formation. The division between the two formations is arbitrary. Lithologically, the Lagunillas formation of the west side of the lake consists largely of light green, greenish gray, gray, and light gray sandstones and claystones. There are occasional lignites, thin glauconitic sandstones, and red and gray mottled claystones. The mottled claystones increase rapidly in prominence westward as the formation grades laterally into the Los Ranchos formation. The formation apparently represents a transition from marine to nonmarine conditions. Brackish water to marine foraminifera and ostracods are fairly common in the lower part of the formation, while the upper part is barren. Streblus beccarii (Linn) and Miliammina fusca (Brady) are particularly characteristic of the lower beds. Fossils suggest lower to middle Miocene age.
The Lagunillas formation on the west side of the lake in general, rests conformably on the La Rosa formation and grades upward conformably into the La Villa formation. However, both contacts may show disconformity and locally south of the city of Maracaibo, the Lagunillas formation is directly overlain by the Onia Beds. The formation grades laterally westward into the Los Ranchos formation.
From its stratigraphic position immediately overlying the La Rosa formation and from its lithologic character and fossil fauna, the Lagunillas formation is believed to be, at least in part, the time equivalent of the Cerro Pelado formation of the State of Falcón. An oil sand in the Bachaquero field in the upper part of the Lagunillas formation is called Bachaquero sand (Sutton, 1946, p. 1698).
For fossil, lists, see Sutton (1949, p. 1700). The Lagunillas formation crops out in the northeastern Bolívar district and southeastern Miranda in the eastern part of the State of Zulia. It is found in the subsurface throughout the Bolívar coastal area and in the eastern and central parts of the districts of Urdaneta, Maracaibo, and Mara. Hedberg and Sass (1937, p. 100) and Sutton (1946, p. 1697) point out that the Miocene Lagunillas formation should not be confused with the Lagunillas conglomerate of Sievers (1888, p. 8-16).
W. A. Mohler
"OLD RED Series"
Permo-Carboniferous and Triassic
State of Zulia
Author of name: Unknown.
Original reference: R. A. Liddle, 1928, p. 101.
Original description: ibid.
According to Liddle (1928, P. 101) the "Old Red Series" is a name which has for a long time been applied to series of brick-red shales, deep-red, fine sandstones, and gray quartzites, outcropping in a broad belt in the Sierra de Perijá and in the Venezuelan Andes of Western Venezuela.
Subsequent studies have proven that the Old Red Series comprises part or whole of the Permo-Carboniferous Palmarito formation and the Triassic La Quinta formation. The name "Old Red Series" is obsolete.
This also applies to the "Red formation" of Oppenheim (1938, P. 39).
See "OLD RED Series"
UPPER DEVONIAN ?
State of Zulia, Venezuela
Authors of name: Geologists of the Caribbean Petroleum Company ( ? ).
Original reference: H. D. Hedberg and L. C. Sass, 1937, p. 79.
Original description: none published
The name Macoíta was probably first used as a formation name by the geologists of the Caribbean Petroleum Company, who pioneered geologic surveys in the Perijá mountain front.
Hedberg and Sass (1937, p. 79) state that the "red shales, siltstones, and sandstones... well exposed on Río Macoíta", and popularly referred to as the "Old Red Series", have been called "Macoíta formation". Liddle (1943, p. 1920) says that the "Old Red Series" is not present on Río Macoíta, and uses the term Río Macoíta formation for the "thinly-bedded, sandy, micaceous gray shales and dark-gray, evenly bedded, quartzitic, fine-grained sandstones which are well exposed on Río Macoíta", eliminating the application that Hedberg and Sass gave to the term Macoíta (which he erroneously cites as "Macoíta series").
The type section (Richmond Exploration Company private report) begins near the "matera" Alirán on the Río Macoíta and extends northwest ward for about three kilometers, to a point about half a kilometer northwest of "hacienda" Puerto Nuevo.
"The Macoita formation is composed predominantly of interbedded olive gray, calcareous, carbonaceous siltstone and medium-gray to olive tan, minutely cross-bedded, fine, arkosic sandstone. Bedding is regular, with thickness of individual strata varying from a decimeter to a half meter or more. The upper 200 to 300 meters is of brick-red siltstone, sandy siltstone, and red and green conglomerate stringers, in a red, sandy and silty matrix. Conglomerate pebbles are red, calcareous siltstone and pinkish-gray, siliceous porphyry." (W. K. Gealy, Richmond Exploration Company private report.) The Macoíta formation is underlain by the Tinacoa formation, apparently conformably. From observations in the adjacent area, the upper contact, with the La Quinta formation, is known to be unconformable, although the unconformity is not readily apparent on Río Macoíta.
Structural complexity, particularly in the lower part, makes it difficult to measure the thickness of the Macoíta, but at least, 1000 meters is reported in the type area. The formation is recognized from a few kilometers south of the Río Macoíta to the Totumo area, about forty kilometers to the north. At the area to the south and west, the formation is veiled in structural complexity and there is a lack of geologic investigations.
No fossils have been found in the Macoíta formation, but it is correlated with the Campo Chico formation of the Río Cachirí area farther north, which Liddle (1943, p. 14, 19) assigns to the Upper Devonian on the basis of stratigraphic continuity (Río Cachirí series) with underlying strata carrying Lower and Middle Devonian fauna.
K. L. Edwards
State of Zulia, Venezuela
Author of name: C. P: Bong, 1927.
Original reference: F. A. Sutton, 1946, p. 1639.
Original description: ibid.
Sutton (1946, p. 1639) stated that the Seco conglomerate is best exposed on the Quebrada Aponcito Seco to the northwest of Machiques in the District of Perijá, State of Zulia. It is described as a dull, reddish black to gray, hard, very coarse, massive, cobblestone conglomerate. The cobblestones are in part igneous and in part derived from the underlying Devonian. In the Quebrada Aponcito Seco, the conglomerate attains its maximum noted thickness of 670 meters. It is unconformable with the Devonian Macoíta formation below and the basal sandstones and conglomerates of the Cretaceous above. The Seco conglomerate crops out in a narrow belt of limited extent along the eastern front of the Sierra de Perijá. It thins in a short distance northward and dies out before reaching the Cogollo River. Its southern extent is not known, but it was observed to occur in the Río Macoita section. Sutton stated that the Seco conglomerate is believed to be correlative with the La Quinta formation. This latter formation is considered to be Upper Triassic in age.
Private information indicates that the Seco conglomerate is now believed to be correlative with the upper part of the La Quinta formation.