Introduction

The Maracaibo Basin (Fig. 82) is the major oil producing area of Venezuela. Extensive micropaleontological studies by the oil industry have, based primarily on foraminifera and palynomorphs, greatly contributed towards the understanding and interpretation of the stratigraphy, correlations and changing environmental conditions of the Cretaceous and Tertiary sediments of the area. Much of this information has remained unpublished. Exceptions to this are the palynological investigations by Kuyl et al. (1955) and Fuenmayor's (1989) ‘Manual on the foraminifera of the Maracaibo Basin’. In addition there exist publications by Barbeito et al. (1985) and Pittelli Viapiana (1989) on the paleoenvironmental significance of Eocene benthic foraminifera in the Maracaibo Basin.

Barbeito et al. (1985) distinguish in the Mara- Maracaibo area (Fig. 82) 14 associations mainly based on benthic foraminifera, each characterizing a certain paleoenvironment, primarily water depth but also on variations in salinity. The range is from shoreline (alluvial) to bathyal. One of the 14 associations is characterized by a strong presence of Globigerina spp. amongst a dwarfed calcareous benthic fauna. On their table 2, intervals of the 14 associations are plotted against the 10 investigated well sections within the area Mara Maracaibo.

Pittelli Viapiana (1989) distinguishes five paleobathymetric foraminiferal assemblages through the Early Eocene to late Middle Eocene of the eastern and northwestern parts of the Maracaibo Basin based on well and surface evidence. They range from lower alluvial, deltaic, nearshore, inner mid-neritic to outer neritic/upper bathyal.

Fuenmayor's (1989) manual, together with the ‘Lexico Estratigrafico de Venezuela’ (1970 edition) forms the base for the following outlines. It draws extensively from Maraven's micropaleontological data.