ARAMINA, Formation

TERTIARY (middle Miocene)

State of Miranda, Venezuela

Author of name: P. P. Wolcott, 1940 (private report).

Original reference: A. N. Dusenbury, Jr. and P. P. Wolcott, 1950, p. 22.

Original description: W. H. Bucher, 1952, p. 59.

A. N. Dusenbury, Jr. and P. P. Wolcott (1950, p. 22) mentioned that on Quebrada Yaguapa, the base of the Miocene Aramina formation lies with angular unconformity upon metamorphosed Cretaceous (Turonian).

E. Mencher et al. (1951, correlation chart) placed the Aramina in the upper half of the lower Miocene. They showed it overlain unconformably by the upper Miocene Tuy formation and underlain with local unconformity by the lower Miocene and uppermost Oligocene Cumaca formation.

W. H. Bucher (1952, p. 59) wrote the first published description of the Aramina in the following words: "In the lower Río Tuy embayment, thick marine conglomerates, assigned to the "Middle Miocene" by Wolcott (unpublished manuscript, Wolcott's Aramina formation), rest with angular unconformity on Eocene, Cretaceous and basic igneous rocks. Their thickness appears to be greater than 5000 feet. Angular fragments of schist lie even in beds of impure limestone intercalated in the conglomerate sandstone series".

R. J. Smith (1953, p. 59) stated that the Aramina formation is nonmarine and assigned it to the early Miocene.

The following description of the Aramina formation is mostly abstracted from a private report by P. P. Wolcott (1945). The formation was named after Quebrada Aramina, a northern tributary of the Río Tuy, which crosses the Caucagua-Capaya road seven kilometers southwest of Capaya. The type section extends from the upstream metamorphics downstream to a point about one kilometer below Los Fernández. The bottom of the section consists of a conglomerate 30 to 50 meters (164-197 feet) thick. This conglomerate includes a few beds of impure limestone containing angular fragments of schist. It is overlain by interbedded greenish gray clay shale, clays and sandstones with a few tan silty limestones in the lower part. The maximum measured thickness of the entire formation occurs in Quebrada Aramina, where 1.656 meters (5,432 feet) of Aramina sediments are present. The Aramina rests unconformably upon Cretaceous metamorphics on the north side of the lower Río Tuy embayment and upon Eocene, Cretaceous and basic igneous rocks on the south side of the embayment. It lies unconformably beneath the Guatire formation (of upper Miocene and/or Pliocene age) in the outcrop area, the upper Miocene Tuy formation having apparently been overlapped. The Aramina is the shallow marine lateral equivalent of the fresh water deposits of the Cumaca formation. It contains abundant marina microfossils and megafossils which indicate a middle Miocene age. Diagnostic mollusks include Anadara (Larkinia) waringi (Maury), Chione cancellata (Linne), Turritella abrupta Spieker, T. gatunensis Conrad, T. mimetes Prown and Pilsbry and Oliva cylindrica Sowerby. The Aramina is geographically restricted to the lower Río Tuy embayment in eastern Miranda.

A. N. Dusenbury, Jr.