CUBAGUA, Beds

See CUBAGUA, Formation.

CUBAGUA, Formation

TERTIARY (upper Miocene and/or Pliocene)

Dependencias Federales, Venezuela

Author of name: L. V. Dalton, 1912.

Original reference: L. V. Dalton, 1912, p. 42.

Original description: none.

The "Cubagua beds" were originally named by Dalton. The type locality is the Island of Cubagua, a Federal Dependency located between the Island of Margarita and the northern coast of the State of Sucre.

2) The Navay facies, predominantly cherty-argillaceous rich in fish remains; of plant material. The Santa Bárbara facies contains, Siphogenerinoides ewoldi. The unit was correlated by Senn, 1939 (1940), ("Stratigraphical Correl-Caribbean Region" ) with beds outcropping at Manicuare, to the west end of the Araya Peninsula. In this Correlation Chart, Senn uses the name "Manicuare-Cubagua beds", under his "Eastern Venezuela" column, to designate sediments which he considers of upper Miocene age and places them stratigraphically above the Santa Inés formation. Liddle (1946, p. 531) refers to the Cumaná beds as sediments which occupy a relatively small area (3 km²) to the east of the small fishing town of Manicuare. These sediments lie in marked unconformity above the Caribbean series.

González de Juana (1947, p. 693, Table I) correlates the Cubagua formation with the Oligo-Miocene Quiamare member of the Santa Inés formation. He places the Cubagua formation below an "Araya formation" (undes-cribed) equivalent to Sacacual, and above an Oligocene? section of mottled clays, equivalent to Merecure (p. 698). González de Juana (1947, p. 699-700) mentions that "a quartzous gravel bed, exposed on the northern side of the Island of Cubagua, at the locality named Las Calderas, does probably represent the Mio-Pliocene boundary". According to this author, the over and underlying formations appear to be conformable. The writer of the present article considers it difficult to establish time boundaries based on such facts, since there are prominent lateral variations in the lithofacies.

According to the observations carried-out by the writer and F. A. Balda, the best surface section of the Cubagua formation ("beds") is exposed typically in the Las Calderas Canyon, the vertical extension of which goes from sea-level to the island top elevation. Said section, with an approximate total thickness of 70 m, is constituted by an interbedding of the following main two lithologic types: coquinoid sandstones, rich in quartz, containing abundant mollusca, and a somewhat arenaceous claystone, containing foraminifera. The basement of the formation does not appear on the surface.

An abundant microfauna, predominantly bentonic and of open marine environment, indicating a uppermost Miocene or perhaps a lower Pliocene age was identified by Sellier de Civrieux (private report) on samples from the Las Calderas Canyon.

Foraminifera: Amphistegina gibbosa, Cibicides americanus, Cribroeponides caribaea (d'Orbigny), (syn. Eponides repandus of some authors, not of Fichtel and Moll), Cibicides isidroensis, Cibicides sinistralis, Elphidium sp. cf. E. poeyanum, Siphonina pozonensis, Nonion grateloupi, Nonion sp. cf. incisum, Streblus becarii var. sobrina, Streblus becarii var. tepida, Streblus sarmientoi, Orbulina universe, Globigerina trilocularis, Globigerinoides triloba, Globigerinella aequilateris, Robulus sp. aff. R. orbicularis, Bolivina subaenariensis var. mexicana, Uvigerina - hispido costata, Uvigerina rutila ?, Cassidulina crassa.

Ostracods: Cythereis vaughani

Sellier de Civrieux says (ibid.): "the sandy and coquinoid formation exposed at Cubagua represents only the younger interval of a 4.000 meters thick Oligo-Mio - ? Pliocene subsurface section, apparantly continuous, which, according to González de Juana (1947, p. 598) comprises, downward, a silty-argillaceous greenish gray, homogenous and compact formation, containing claystone layers, and further down a mottled unit, typically continental. The upper formation of the cycle, typically arenaceous, macro and microfossiliferous (Cubagua, formation), appears to be the only part of the section to be equivalent with the beds observed to the south (Punta Araya and San Antonio at Cumaná) and east (southern part of Margarita) and which G. P. Wall (1860) referred to as a lower calcareous series of his younger Parian System. These beds overlie with marked unconformity, formations of different ages which indicates a marine overflow in the upper Miocene or/and Pliocene, from Cubagua to the areas above mentioned. (See also CUMANA, Beds)

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