Correlation of the Jurassic through Oligocene Stratigraphic Units of Trinidad and Northeastern Venezuela

The Jurassic through Oligocene stratigraphies of Trinidad and the Serrania del Interior of eastern Venezuela exhibit many similarities because of their proximity on the passive continental margin of northeastern South America. A slightly later subsidence in eastern Venezuela, and the generally deeper-water sedimentation in Trinidad, is interpreted to be the result of a serration of the original rift margin, producing an eastern Venezuelan promontory and Trinidadian reentrant. We interpret these serrations to be the result of oblique (NW-SE) spreading of North and South America during Middle and Late Jurassic time. The stratigraphies of northeastern Venezuela and Trinidad contrast in the Hauterivian-Albian interval, with dynamic shallow shelf environments prevailing in the Serrania del Interior and deeper marine submarine-fan deposition in Trinidad. Both areas develop middle to Upper Cretaceous source rocks during a time of eustatic sea level high and widespread oceanic anoxia. A slight lowering of eustatic sea level may have been responsible for the clastic influx represented by the sandstones of the Maastrichtian San Juan and Galera formations, disturbing the previous pelagic and hemipelagic sedimentation. The seaward transport of these sandstones may have been responsible for the localized erosion of the Maastrichtian section in central and southern Trinidad. Sedimentation stabilized with slope and outer-shelf turbiditic deposition during the Paleocene and Early Eocene, before diachronous, west-to-east shallowing occurred. Shallowing from the turbidites to shallow-water limestones and sandstones occurred in eastern Venezuela in the late Middle Eocene, and in the Late Eocene/Early Oligocene in Trinidad. Alhough eustasy and sediment progradation could have influenced the shallowing, its magnitude and rate requires that a tectonic uplift have occurred. Margin buckling, caused by the N-S relative convergence of North and South America, and forebulge uplift ahead of the Caribbean plate both are possible mechanisms. Following the shallowing, both areas subsided rapidly into laterally variable Oligocene to Recent flysch-like sedimentation. This is interpreted to represent the onset of direct interaction of the Caribbean plate with the South American depocenters of Trinidad and eastern Venezuela. Miocene to Recent sedimentation has been strongly influenced by these plate interactions.