HIGH RESOLUTION BIOSTRATIGRAPHY IN THE "LA BLANQUILLA" BASIN, OFFSHORE VENEZUELA

High resolution biostratigraphy (Foraminifera and Calcareous Nannoplankton) of 3 wells from "La Blanquilla" Basin, offshore Venezuela was done in order to establish a chronostratigraphic framework and to define paleoenvironmental conditions for the Oligocene-Lower Miocene age reservoirs. Seismic sections indicate more than 6 kms of thickness of sediments from Eocene to Recent. Structurally, "La Blanquilla" has been interpreted as a back-arc basin associated with the subduction of the Atlantic Plate under the Caribbean Plate during the Paleogene. It has SW-NE orientation and is divided by the Margarita Fault into two sub-basins which have different geological histories due to tectonism. The column in the west sub-basin shows a complete section from the Eocene to the Oligocene (zones P11 to P22 and zones NP25 to NN1). The overlying Lower Miocene section shows an inner unconformity, followed by a Middle to Late Miocene section which is unconformably overlain by rocks of Late Pliocene to Pleistocene age. The paleobathymetries indicate bathyal depths, but shallowing to nerithic from Middle Miocene to Recent. The section studied in the east sub-basin, shows a continuous sedimentary column from Late Oligocene to Middle Miocene (zones P19 to N10 and zones NP24 to NN4; bathyal).This section is also unconformably overlain by rocks of Pleistocene age. Sequence biostratigraphy candidates (MFS and SB) and a correlation of the 3 wells are included. This work is fundamental to understand the evolution of the basin and to support petroleum exploration.