LAS FLORES, Formation

TERTIARY (upper Eocene)

State of Zulia, Venezuela

Author of name: H. D. Hedberg, 1927 (private report).

Original reference: F. A. Sutton, 1946, p. 1679-1683.

Original description: ibid.

Sutton (1946, p. 1679-1683) stated that the name Las Flores is derived from a small settlement in the north of the District of Bolívar, Zulia, east of Lake Maracaibo. The name was originally applied to sandstones which crop out in the immediate vicinity. Sutton used it to define one of the major subdivisions of the upper Eocene. He described the Las Flores formation as a shallow-water facies of the upper Paují formation consisting of gray, finely laminated, pyritic, carbonaceous shale, interbedded with finegrained, light gray sandstone. Sutton pointed out that the thickness of the formation is extremely væriable in view of the post-Eocene erosion which has in many places removed it entirely. The maximum thickness of the Las Flores formation is 1,308 meters in the well Icotea-1. West and north of the city of Maracaibo on the west side of the lake, the formation is much thinner and in places is entirely missing. The Las Flores formation is everywhere conformable and gradational with the underlying Potreritos formation. It is generally impossible to define the contact with reliable accuracy, but in practice the boundary is usually set, according to Sutton, at the point where the grains of "pebbled" garnet first consistently outnumber the grains of "dodecahedral" garnet. Throughout the northern part of the Bolívar Coastal field, the Las Flores formation is overlain unconformably by the upper Eocene Ambrosio formation, while in the District of Miranda on the north it is overlain unconformably by the upper Eocene Churuguarita formation. Elsewhere, middle Oligocene or younger formations rest unconformably on the Las Flores formation. Outcrop occurrences of the formation are common in the area northeast and north of the Bolívar Coastal field. The Las Flores is an important subsurface formation in the Bolívar Coastal field. It passes by lateral transition into the upper Pauji formation eastward and southward. On the west side of the lake, isolated areas of outcrop are found in the vicinity of the city of Maracaibo. The Las Flores crops out on the crest of various structures in the District of Mara and slightly below the surface in the La Concepci6n field in the District of Maracalbo. Many wildcat wells in the District of Urdaneta have penetrated into the Las Flores. Sutton gave a detailed faunal list (p. 1681) of micro and macrofossils. Sutton pointed out that the Las Flores formation is the exact equivalent of the combined Orumo formation and the Taparito member of the Mostrencos formation of Hedberg and Sass (1937, p. 91-93). Sutton stated that the El Mene formation of Hedberg and Sass (1937, p. 93) is the equivalent of the combined Las Flores and Potreritos formations. According to Sutton, two other exact equivalents of the Las Flores formation are the Palmarejo beds of Liddle (1938, p. 303-307) and the Caiiadones formation of Garner (1926, p. 682).

At present the names Palmarejo beds and Cañadones formation have become obsolete as synonyms of the Las Flores formation.

Leo Weingeist