GUAVINITA, Formation

UPPER CRETACEOUS (pre Maestrichtian)

State of Guárico, Venezuela

Authors of name: J.M. Patterson and J.G. Wilson, 1953.

Original reference: J. M. Patterson and J. G. Wilson, 1953, p. 2714.

Original description: ibid, p. 2714-2715.

The Guavinita formation was described by Patterson and Wilson (1953, p. 2714-15) as a subsurface formation occurring in the Las Mercedes region, state of Guárico. The name is derived from the Guavinita field of the Las Mercedes area where a good section is developed.

The Guavinita formation forms the upper part of the Temblador group of Patterson and Wilson (1953, p. 2711) and is defined as all beds of Cretaceous age above the Infante limestone. The type section for the Guavinita formation is from the well Guayabo-2 in the Las Mercedes oil field.

In M-8 well of the Las Mercedes field, a section corresponding to the type section is 365 feet thick, and consists of a basal shale 50 feet thick overlain by 100 feet of sand and thin limestones. Fish remains and chert beds are associated with the sand and limestone. Above the zone of fish remains and chert, the section is predominantly sandstone. In the east, near Valle de La Pascua, the Guavinita is about 900 feet thick and progressively thins to the west due to pre-La Pascua eastward tilting and subsequent erosion.

The exact age of the Guavinita formation is uncertain. According to Patterson and Wilson (1953, fig. 3, p. 2712), the Guavinita formation is preMaestrichtian. The lower part of the formation may be equivalent to a portion of the La Luna formation of Western Venezuela (Patterson and Wilson, 1953, fig. 3, p. 2712), which in turn is Turonian and possibly Coniacian in age (Mencher et al., Chart I, p. 774).

S. J. Brown