AGUA SALADA, Group

TERTIARY (Oligo-Mioceno)

State of Falcón, Venezuela

Author of name: M. L. Thomas, 1919 (private report).

Original reference: C. Wiedenmayer, 1924, p. 508-512.

Original description: ibid.

The name Agua Salada was created in 1919 by M. L. Thomas (private report). C. Wiedenmayer (1924, p. 508-512) first used the name Agua Salada in publication for a succession of about 1000 meters of clays and marls in Eastern Falcón. In his "Stratigraphisches Normal-profil für Ostfalcon", he divides his "Tonmergelserie" into "Obere Agua Saladaserie" (Miocene) and "Untere Agua Saladaserie" (Oligocene), separated by a discordant unconformity. Both units show and identical lithological composition. Towards the west, the lower part of the claymarl series becomes more quickly sandy than the upper part, and there is no more perceptible discordance between tlie two units. The term Antón Coro beds was applied by R. A. Liddle (1928, correlation chart) as synonym of his Agua Salada clays.

A. Senn (1935, p. 76-77) created a biostratigraphic subdivision of his "Aguasalada Tone" into six foraminiferal zones which he termed A1c, A1a, A2, A3, A3-4 and A4 zones.

H. H. Renz and H. H. Suter presented at the Trinidad Geological Conference, April 18-27, 1939, a paper entitled "The Pozón and El Mene de Acosta type sections of the Agua Salada formation", published by H. D. Hedberg in abstract (1939, p. 1242). The Agua Salada is elevated to formation rank with designation of type localities at Pozón and El Mene de Acosta, Eastern Falcón. The age of the formation is given as upper Oligocene to middle Miocene. J. A. Cushman and H. H. Renz (1941, p. 1-27) described a great number of new foraminifera from the formation, distributed over seven foraminiferal zones and extending from the Upper Oligocene to the middle (and partly ?upper) Miocene. H. H. Renz described (1942, p. 552-55) the Agua Salada formation as consisting of about 1500 meters of more or less uniform black-gray calcareous clays with occasional layers of marl, glauconitic sand and silt.

R. A. Liddle (1946, p. 433-434) first used the Agua Salada as a group name, also mentioned by H. H. Suter (1947, p. 2195).

H. H. Renz (1948, p 8-27) described the Agua Salada group with type sections at El Mene de Acosta and Pozón, State of Falcón. It is named after Quebrada Agua Salada, Pozón, and is approximately 1442 meters thick. It is subdivided lithologically into the San Lorenzo formation (El Salto sand member and Menecito clay member) and Pozón formation (Policarpio greensand member, Husito marry clay member and Huso clay member). The San Lorenzo formation, with type locality at El Mene de Acosta is approximately 400 meters thick, and the Pozón formation, with type locality at Pozón, shows a thickness of about 1042 meters. Fossil evidence indicates that the Agua Salada group is middle Oligocene (Rupelian) to middle Miocene (Tortonian). The San Lorenzo formation is considered middle to upper Oligocene and the Pozón formation, upper Oligocene to middle Miocene.

The Agua Salada group is conformably underlain by the Guacharaca formation, and is in transitional and conformable contact with the overlying Ojo de Agua formation.

Agua Salada as a group, has a geographic extent of a least 60 kilometers in the southern part of the Agua Salada Basin, striking in an east-west direction along the El Mene de Acosta-Pozón anticlinal axis. The width across strike may be as much as 12 to 15 kilometers. Toward the north and northwest, the Agua Salada group is gradually changing into a fairly uniform and thick calcareous clay formation. Toward the southeast, south and west, the group passes into a number of near-shore sandstone and limestone formations (Bachacal formation, Riecito limestone, Capadare limestone) of greatly variable thicknesses.

Biostratigraphically (foraminifera), the sequence comprises the Uvigerinella" sparsicostata zone (middle Oligocene), Acostian stage, (mainly upper Oligocene), Araguatian stage (upper Oligocene to lower Miocene) and Lucian stage (lower to middle Miocene).

H. H. Renz