MITARE, Group

TERTIARY (Oligocene)

State of Falcón, Venezuela

Author of name: J. H. Pantin H., 1947 (private report).

Original reference: E. Mencher et al. 1951, correlation chart.

Original description: none published.

Mencher et al. (1951, correlation chart) first published "Mitare group", which had been introduced by Pantin to include the San Juan de la Vega, Pecaya and Pedregoso formations (see) of the Río Mitare valley at central Falcón, replacing "San Luis stage" of Senn (1935, p. 72). Many Falcón Oligocene formations are of local facies development, each representing all or a part of geologic time from lower to upper Oligocene. To refer to the whole middle Oligocene deposition, several petroleum geologists have also embraced in Mitare group the Guarabal, Patiecitos, San Luis, Acurigua, Churuguara and El Paraíso formations (see). Some of these formations have not yielded sufficient fossils to determine their exact age, but recent studies show all to be post-Eocene and pre-uppermost Oligocene.

Heretofore an Eocene age for the El Paraíso formation had been based on lithologic analogy (Liddle, 1946, p. 333), on mistaken stratigraphic position (Seen, 1935, p. 60, 71) or on mislocated orbitoid samples (Gravell, 1933, p. 14) (see quotations under EL PARAISO, Formation). Identification of Bulimina sculptilis, Eponides crebbsi, Uvigerina mexicana and many other species now proves a post-Eocene age for the El Paraíso and hence for all the overlying sediments in central Falcón.

G. D. Jobnson

EL PARAISO, Formation

TERTIARY (Oligocene)

State of Falcón, Venezuela

Authors of name: F. Hodson, G. A. Weaver and G. D. Harris, 1925 (private report).

Original reference: F. Hodson, 1926, p. 3.

Original description: ibid.

The complete original reference and description of this formation is as follows (F. Hodson, 1926, p. 3):

"El Paraiso shales.- Black shales with interbedded coals and quartzitic sandstone layers. Type locality: El Paraíso, in Quebrada El Paraíso, District of Bolívar, State of Falcón".

No indication was given of the age nor relation with other formations. R. A. Liddle (1928, p. 205-206), without mentioning Hodson's formation by name, mentions the El Paraíso locality and describes beds there which agree with Hodson's description. His description reads in part:

"In Río Paraíso at El Paraíso on the Pecaya-Churuguara road, there are good exposures of highly contorted, black, coal-bearing, arenaceous, ferruginous nummulitic, concretionary shale, weathering red, with which are interbedded thin, quartzitic, blue-gray sandstone. All of the sediments are highly twisted, faulted, and cut by quartz veins" (p. 206).

Whether the sandstone which he describes in the next sentence belongs with Hodson's El Paraíso beds, we are unable to say; Liddle apparently thought not. He continues: "...At the top of the bluff, on the northeast side of Río Paraíso, there is a large ledge of massive, white, moderately coarse, well-bedded, quartzitic sandstone... distinctly conformable with the underlying coal-bearing shale. The black coal bearing shale... is referred to the lower part of the Misoa-Trujillo formation and correlated with coal-bearing shales of this horizon over a great part of Venezuela; the horizon in western Venezuela is known as the Third Coal. The massive sandstone lying to the south (sic) of Paraíso is referred to the upper part of the Misoa-Trujillo. . ., and is correlated with the... Mirador sandstone horizon of this formation".

Liddle refers the "Third Coal horizon" as middle Eocene, the "Mirador" as upper Eocene.

In the next paragraph, he describes other exposures of the "Misoa-Trujillo" in the same region; one in the second crossing of Río Paují, and again, from 2 km south of this second crossing along the Pecaya-Churuguara trail as far as the northern flank of the Cordillera de Agua Negra.

Liddle's description of outcrops near "Cerro El Paraíso" (p. 255) "between Carrizal and Agua Larga in the District of Bolívar, State of Falcón" refer to the San Luis limestone, as is clear in his discussion. The coincidence of two El Paraíso in the Distrito Bolívar is unfortunate.

The name "Paraíso series" appears in Gravell (1933, p. 7, 14), who states that Kugler thinks it middle Eocene, but that it probably is also upper Eocene. Gravell identified Discocyclina sp. indet. (probably D. flintensis (Cushman) ), from locality N° 1142, and he notes that Gorter and Van der Vlerk (1932, p. 111) identified D. flintensis from the same locality. This locality (identified as "El Oso-Paujicito" by Gorter and Van der Vlerk, by Gravell as "Buena Vista, state of Lara"), is, according to Senn (1935, p. 60) within the Santa Rita conglomerate. (Gorter and Van der Vlerk had referred it to the "Paloma Alta series"). This fossil, therefore, has no bearing on the age of Hodson's type El Paraíso beds.

Senn (1935, correlation table) correlated the "Paraíso beds" with the upper part of the upper Misoa-Trujillo, that is, as upper middle Eocene. In his correlation table of 1940, he associates the "Paraíso beds and Mojino quartzites", as representing upper middle Eocene in eastern Falcón, underlying the Tupure shales.

In 1946, Liddle (p. 333) repeats textually his 1928 description of the El Paraíso outcrops, except that he now correlates the sandstones south of El Paraíso with the "Misoa sandstone horizon". Although he does not relate the description to Hodson's formational name, on the preceding page, he mentions that, in western Falcón and northern Lara, "the quarzitic sandstones" (of Agua Larga, the Serranía de Baragua, Cuesta Mojino, Cerro Chimborazo) "probably belong to the Paraíso beds of the upper part of the Misoa-Trujillo formation. Locally these beds have been called Mojino quartzites". He adds that it has been impossible to measure a type section, but that single hills expose over 1,000 feet of section "and it is probable that the full thickness of 2,000 to 2,500 feet is present in the region". (Liddle, 1946, p. 332). On p. 333, he correlates the "Misoa-Trujillo" with the "Lower Middle Eocene".

Sutton (1946) mentions the El Paraíso "formation" as a probable correlative of the upper Eocene Omuquena formation (p. 1675) and also as correlative with the Mene Grande (p. 1687).

Geologists who have worked in the region from the type locality of the El Paraíso beds, across southern Falcón, now believe that the Mojino quartzites of Halse (1937), the San Juan de la Vega sandstone of Senn (1935) and the El Paraíso beds are all equivalent, and that the age is not Eocene, but Oligocene. They propose to retain the name El Paraíso for this unit, as being the first name published. It is to be hoped that a more satisfactory definition and description of a type section may be published sometime, since all the published data are either incomplete or actually misleading (e.g. Senn's statement, 1935, p. 60, that the Paraíso is folded together with the Paují and overlain unconformably by the Santa Rita).

Frances de Rivero