MOJINO, Beds

See MOJINO, Quartzites.

MOJINO, Quartzites

TERTIARY (Eocene ? Oligocene ?)

State of Falcón, Venezuela

Author of name: W. M. Norris, 1925 (?) (private report).

Original reference: G. W. Halse, 1937, p. 188-190.

Original description: ibid.

The name Mojino quartzites (with "Misoa-Trujillo, as a synonym) was published by G. W. Halse (1937, p. 188-190) for a formation occurring in the western Buchivacoa district. The name is evidently derived from the town of El Mojino (which appears on Bucher's geologicteetonie map of Venezuela, a little to the west of center of quadrangle D: 10-11). The Mojino quartzites were described as principally light-gray quartzites with hard sandstones and some beds of ealeareous quartzite, occasionally ripple-marked and with some bands of dark crystalline limestone; interbedded with these are laminated gray or black clays and laminated carbonaceous clays. The Mojino quartzites are said to occur stratigraphically below the Tupure shales and to form a ridge of hills in southeast Buchivacoa, ocourring in an anticlinal fold flanked by the Tupure shales on the north and south sides (see pl. 3 of Halse's paper). The beds are said to be so highly folded and faulted that no measurements of thickness were possible.

Senn (1940, correlation table, p. 1580) grouped the Mojino quartzites together with the "Paraiso beds", as representing the upper part of the middle Eocene in central Falcón.

In 1946, Liddle (p. 332) mentions "Mojino beds" as a local name for sandstones in central and southern Falcón and northern Lara, giving "Paraiso beds" as a more general name; he describes these beds under the general heading of "Misoa-Trujillo formation /Third Coal Horizon/ Misoa Sandstone". He states that an accurate section has not been measured, but that sections exposing over 1000 feet are common, and "it is probable that the full thickness of 2,000 to 2,500 feet is present in the region".

Some geologists working in southern and western Falcón believe now that the Mojino quartzites, Paraíso beds and the San Juan de la Vega sandstones are all the same formation, and that the age is Oligocene, not Eocene. They propose to retain the name El Paraíso for this formation, as being the first one published. (See also articles EL PARAISO, Formation; and SAN JUAN DE LA VEGA, Sandstone).

Frances Rivero