Oceanographic reconstruction of late Cenozoic deposits from northeastern Venezuela

Resumen

The late Cenozoic sedimentary deposits of southern Caribbean are particularly well-exposed in the Araya Peninsula (NE Venezuela). This sequence records a complex response to strike-slip tectonics associated to the Caribbean and South America plate motions during the Late Miocene-late Pleistocene. Upper bathyal sedimentation during the Late Miocene ended with a tectonic uplift pulse. During the Pliocene and Pleistocene, sedimentation was characterized by mixed carbonate-siliciclastic platform deposits. Co-presence throughout the most of the section of warm/oligotrophic planktic surface foraminifera and cooler, deeper water taxa suggests that seasonal upwelling was taking place throughout the late Cenozoic. The ~120 m thick section was previously described as a complete record of the time represented by the planktic foraminiferal Globorotalia acostaensis - Globorotalia truncatulinoides Zones. However, the presence of three major discontinuities (5.6, 4.2 and 1.6 Ma.) correlated to regional stratigraphic hiatus in separated basins suggests the existence of a regional tectonic process affecting this sequence. In addition, oceanographic conditions of surface waters are rather different between the Late Miocene-Early Pliocene and the Late Pliocene, with major changes in trophic conditions.