The margin of northern Venezuela is a complex zone representing the orogenic events from basement formation to subsequent subduction and exhumation during transpressional collision. This boundary zone has six east-west–trending belts that each record a different segment of its development. This geologic complexity requires radiometric ages to unravel, and we herein provide 48 new ages including U-Pb (4), Rb-Sr (2), 40 Ar/ 39 Ar (24), zircon and apatite fission-track (17), and 14 C (1) ages to constrain the evolution of three of these belts. These three belts are the Cordillera de la Costa, Caucagua–El Tinaco, and Serranía del Interior belts. In the Cordillera de la Costa belt, U-Pb geochronologic data indicate portions of the basement igneous and metaigneous rocks formed in the Cambro-Ordovician (513–471 Ma). New 40 Ar/ 39 Ar data from Margarita Island indicate that some of the subduction complex was rapidly cooled and exhumed, whereas other portions indicate slower cooling. This contrasts with new 40 Ar/ 39 Ar data from the Puerto Cabello portion of the subduction complex that has Eocene to Oligocene (42–28 Ma) cooling ages. New fission-track data imply the entire Cordillera de la Costa belt from Puerto Cabello to La Guaira (∼150 km) was uplifted at the same time. In the Caucagua–El Tinaco belt, the oldest 40 Ar/ 39 Ar amphibole ages from the Tinaquillo ultramafic complex are Jurassic (190 Ma). Additional amphibole 40 Ar/ 39 Ar cooling ages are older than previously recorded in either the Tinaco or Tinaquillo complex. One amphibole 40 Ar/ 39 Ar cooling age for the Tinaco complex is similar to previous U-Pb results. New apatite fission-track results from the Serranía del Interior foreland fold and thrust belt are synchronous with exhumation in the Cordillera de la Costa belt. In addition, several zircon fission-track ages in the Serranía del Interior belt are older than their fossil ages, indicating a Cretaceous minimum provenance age for Miocene beds. Significant new findings from these geochronologic studies include (1) several igneous and metaigneous bodies that may be correlated with orogenic events in the Appalachians occur within the subduction mélange; (2) the Tinaquillo complex may record Jurassic rifting; (3) Cretaceous source rocks for the Serranía del Interior sedimentary strata; (4) exhumation of the subduction complex is segmented because two regions have significantly different cooling histories, with Margarita Island exhumed in the Cretaceous, whereas to the west, the Puerto Cabello region has widespread Paleogene cooling and exhumation ages; and (5) earthquake activity in 1812 caused uplift as recorded by exposure of Recent corals.

ABSTRACT The understanding of the plate tectonic interactions between the Caribbean, South America, and Atlantic plates and their integration with the timing of the basin configurations, its source rock deposition, and thermal maturation provides important insights to interpret the Venezuelan petroleum systems. The different tectonic settings in northern Venezuela offered the right environmental conditions for the deposition of world-class–Cretaceous organic-rich source rocks all through its northern margin, allowing the generation, expulsion, migration, entrapment, and geographical distribution for most of the 1.8 trillion bls of original oil in place and 200 TCFG in discovered-proven resources in the 14 main basins of Venezuela. The integrated and comprehensive approach of this study allowed the proposal of an orogenic float partitioning tectonic model that couples the development of the southern Caribbean plate along oblique terrane accretions and subduction below northern South America concurrently with the Atlantic oceanic-crust subduction below the Caribbean plateau. The orogenic float glides on the underlying Caribbean–South American lithosphere coupling, along a basal decollement surface with two deformation fronts that forced a foreland basin to the south in the arc–continent collision (“A” subduction) and coeval forearc basins on Caribbean oceanic-crust subductions under Caribbean terranes or “B” subduction. Right-lateral–strike-slip fault activity along the Oca, San Sebastian, El Pilar, and Arima systems occurs synchronously with the eastward rejuvenation of Caribbean accretion and thrusting. These offsets are the consequence of the oblique convergence between the plates to balance the eastward displacement with the southward thrusting and foredeep subsidence. We report evidence for 100 km (60 mi) of right-lateral displacement along the Oca fault. In our model, the orogenic float used the weakness of the crust along old transform system that formed during the Mesozoic rifting event, to create internal strain-partitioning and displace the arc–continent deformation front along northwest–southeast right-lateral transfer-fault systems of Barquisimeto, Burro Negro, Guárico, Margarita, Urica, and Tobago to name the most important. This succession of tectonic events had implications for basin development north and south of the suture, on the autochthonous side and on the transported terranes. The understanding of the Andean orogenesis as well as the rest of the northern ranges, and the timing and subsidence of adjacent basins, along with the related petroleum systems allowed us to identify and locate from Eocene to present the main oil and gas kitchens for the Cretaceous and Cenozoic source rocks in northern onshore and offshore Venezuela. This facilitated the identification of remaining exploration potential even on mature and explored basins, such as the Cretaceous and Eocene-subcrop plays in Golfo de Venezuela, the foreland subthrust belt play in Ensenada de Barcelona with autochthonous Cretaceous to Paleogene reservoirs, a possible pre-Cretaceous source rock within Espino graben, and several transtensional and transpressional plays in the offshore basins of Blanquilla, Cariaco, Bonaire, and northeastern Falcón basins.