CERRO PELADO, Formation

TERTIARY (upper Oligocene)

State of Falcón, Venezuela

Author of name: R. Arnold, 1911 (private report)

Original reference: R. A. Liddle, 1928, p. 272.

Original description: R. A. Liddle, 1928, p. 272-273.

Although the term Cerro Pelado was first applied by Arnold during private investigations from 1911 to 1916, the first published reference to and description of it is believed to be that of Liddle (1928, p. 272, 273). The Cerro Pelado formation crops out in the foothills of central and western Falcón. It consists mainly of light to medium gray, sandy, gypsiferous, carbonaceous, and locally lignitic shales and claystones with thin ferruginous concretionary streaks, and a considerably lesser amount of intercalated sandstone beds some of which attain significant thicknesses. The sandstones are light to yellowish gray with local reddish-brown tints, hard to friable, and in places cross-bedded and ripple-marked. In the vicinity of the El Mene de Mauroa oil field of western Falcón, Halse (1947, p. 2174) describes the Cerro Pelado as consisting of sandstones, conglomerates, shales, thin limestones, with detrital coal as an exceptional constituent. In origin, the formation represents a transition from the marine environment of the underlying Agua Clara to the very near-shore to coastal plain environment that prevailed when the overlying Socorro formation was deposited. A thickness of about 5,000 feet is reported for the Cerro Pelado in the type locality: Cerro Pelado and Cerro Hormiga, west of the village of Agua Clara. This thickness includes, however, some 2,000 feet of an upper member referred to as the Querales shales by Senn (1935, p. 80). In the El Mene de Mauroa area, Halse (1947, p. 2174) reports a thickness of 2,500 feet. The Cerro Pelado fauna includes mollusks, algae, echinoids, bryozoa, and foraminifera that indicate correlation with the Aquitanian of Europe. The Hombre Pintado sandstone of western Falcón (Liddle, 1928, p. 276, 278) is at the base of the Cerro Pelado; and the El Isiro coal series south of Coro, in north-central Falcón (Liddle, 1928, p. 383-384); Williston and Nichols, 1928, p. 450; Wiedenmayer, 1937, p. 69; Liddle, 1946, p. 449), is in the upper part of the Cerro Pelado as currently defined.

W. M. Chappell