PIEDRAS BLANCAS, Limestone

TERTIARY (upper Eocene)

State of Zulia, Venezuela

Author of name: V. van Raadshoven, 1951.

Original reference: R. van Raadshoven, 1951, p. 482.

See PALOMA ALTA, Formation

PALOMA ALTA, Formation

TERTIARY (upper Eocene)

State of Zulia, Venezuela

Author of name: C. W. Creek, 1925 (private report).

Original reference: N. E. Gorter and I. M. van der Vlerk, 1932, p. 115.

Original description: C. González de Juana, 1951, p. 277.

The name Paloma Alta series is apparently for the first time mentioned in literature by Gorter and van der Vlerk (1932, p. 115), however, without giving a lithological description. Senn (1935, p. 60) mentions the name as well and believes that the Paloma Alta is the equivalent of his Santa Rita conglomerate, a statement which is based on the comparison of larger foraminifera.

According to Sutton (1946, p. 1685) the Paloma Alta series of Senn, consisting chiefly of shales and unconformably overlying the Paují shales in the southeastern part of the Bolívar district, should probably be included in the upper Eocene Ambrosio formation.

The first description of the Paloma Alta formation is given by González de Juana (1951, p. 277). The type locality is in the Paloma Alta hill, in the eastern part of the Bolivar district, State of Zulia. The Ethology is characterized by the presence of shales, more or less conglomeratic sandstones and reef limestones; in the Trujillo spur, the lower part is generally formed by coarse and calcareous sandstones. In the N. E. flank of the Ballenato anticline the Piedras Blancas limestone occurs, which, according to van Raadshooven (1951, p. 482) forms the basal part of the formation.

The formation is locally fossiliferous, containing lamellibranchs and echinoids; its microfauna is very well developed, with the exception of the sandy zones, where it is much poorer, but frequently contains orbitoids such as: Lepidocyclina pustulosa Douvillé and species of Camerina jacksonensis Gravell, which is one of the index fossils of this formation. According to Schaub (1948, p. 227, table I) the Paloma Alta formation correlates with the Churuguarita formation.

The Paloma Alta formation is transgressive on the oldest Eocene. In some localities it can be observed resting on Misoa-Trujillo, but more frequently, only the hiatus of the Mene Grande formation marks the transgres

The maximum thickness is estimated at more or less 2,000 metres, but in some regions, as in the Río Capozón, it thins out to 100 meters.

C. Francken