Late Cretaceous and Mid-Tertiary Palynological Assemblages from the "El Furrial" Area Wells, Venezuela

FASOLA, ARMANDO, and IRAIDA PAREDES, Intevep, S.A., Caracas, Venezuela

The Maturn subbasin, located within the Eastern Venezuelan basin and where the "El Furrial" field was discovered, has been the subject of great exploration interest, since large amounts of oil were found in the last decade. This paper is part of a multidisciplinary effort to better understand the geology of the area.

From the late part of the Paleogene onward, this subbasin developed as a foreland type basin, flanked to the north by a mountain belt: the Serrana del Interior. The stratigraphic nomenclature previously established in the Serrana del Interior was used in subsurface studies, but sometimes with unsuccessful results. An attempt is made in this paper to clarify in part the nomenclature since the biostratigraphic point of view sees the ages determined in subsurface not completely agreeing with those established for the surface formations.

The palynological studies carried out on well samples from the "El Furrial" field have shown the presence of a Late Cretaceous sequence with terrestrial pollen and spores assemblages, and marine microplankton, through which the sequence was dated as Early to Middle Maastrichtian. Toward the top, the sequence contains paleosols, and the palynomorphs are scarce and nondeterminant. The paleoenvironments vary from marine nearshore to subaereal in the Cretaceous.

Immediately after a glauconitic section was deposited the first Tertiary (Oligocene) palynomorphs and foraminifers appear, thus showing an important time gap not completely determined as yet. The paleoenvironments suggested for this Tertiary sequence are marine, probably of the shelf on the neritic zone.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)