Título: Campanian bolivinoides and microfacies from the La Luna formation, western Venezuela

Autor: De Romero, L M.; Galea-Alvarez, F A.;

Fuente: Mar. Micropaleontol, 26(1-4): 385-404, dec 1995

Evento: 5th Calif Univ, Berkeley, Foraminifera Int. Symp.

Lugar y fecha del Evento: Berkeley, CA, Jul. 5-9

Descriptores: Venezuela; Biostratigraphy; Facies; Fauna; Foraminifera; Geology; Invertebrate; La Luna Formation; Microfacies; South America; Stratigraphy; Tres Esquinas FM

Año: 1994

País de publicación: United States

Tipo de documento: Conferencia

Resumen

Tres Esquinas, the upper member of the La Luna Formation, a 1- to 3-m thick condensed sequence composed of glauconitic phosphorite, signals the commencement of the Late Cretaceous regression in W. Venezuela. This is the last of a series of thin phosphatic beds, the others non-glauconitic, occurring in the upper La Luna Formation. In the State of Merida, the presence of Bolivinoides culverensis restricts these phosphatic beds to the late Santonian-early Campanian, with the Tres Esquinas Member assigned to the Globotruncanita elevata-Globotruncana ventricosa zones. Bolivinoides sp. cf. B. sirticus is also commonly found in these beds. On the basis of lithology, mineralogy, foraminiferal content, and degree of bioturbation, 6 microfacies and one sub-microfacies are identified. The microfacies of the phosphatic limestones containing Bolivinoides spp. are notably different in the 2 states.