"BACHACAL-SANDE"

See BACHACAL, Formation

BACHACAL, Formation

TERTIARY (upper Oligocene to lower Miocene)

State of Falcón, Venezuela

Author of name: W. T. Keller and A. Senn, 1931 (private report).

Original reference: A. Senn (1935, p. 82).

Original description: ibid.

This unit appers to have been named by W. T. Keller and A. Senn in 1931 (private report) and A. Senn (1935, p. 81) first published it under the name Bachacal-Sande of the Upper Socorro formation, overlain by the Obere Bachacal-Schichten of the Lower Damsite (now called Caujarao) formation. These beds are exposed in the mountains of Agua Linda, Riecito and Cerro de la Misión, Eastern Falcón. The Bachacal-Sande are not further described but the Obere Bachacal-Schichten are stated to consistof 150 meters of sandy limestones, rich in mollusk remains, interbedded with some marl layers. The sandy limestones contain Arca patricia Sowerby and Turritella abrupta Spieker; and the marl layers yield foraminifera of the A1a Agua Salada zone. The bachacal beds are conformably overlain by the Lower Miocene Riecito limestone (Miogypsinen-Kalk of Senn) and the base is not exposed.

Senn (1940, p. 1580) list the Bachacal as a formation and correlates it with the lower A1a, A2 and A3 Agua Asalada zones. Liddle (1946, p. 434, 459, 461) refers to this unit as Bachacal beds.

The Bachacal formation, which may reach a thickness of more than 800 meters, represents the marginal and near-shore facies equivalent of the middle part of the Agua Salada group. In the nomenclature of H. H. Renz (1948, p. 19-27, 44-66) the formation correlates most probably with the Husito marly clay member and the basal part of the Huso clay member of the Pozón formation. It is covered by the upper Acostain, Araguatian and the lower Lucian stages, to which an upper Oligocene and lower Miocene age is assigned.

The Bachacal formation is sometimes referred to as Casupal beds (Liddle, 1946, p. 449), considered to be a synonym.

H. H. Renz