Knowledge of the geologic evolution of the northern margin of South America has increased tremendously, inspired by the occurrence of huge hydrocarbon deposits. This margin originated in late Triassic time when the supercontinent of Pangea broke up and North and South America drifted apart. The passive margin accommodated a thick sequence of Jurassic to Tertiary sediments. During the latest Cretaceous to the Present, the Antilles volcanic arc, built upon the Caribbean plate, migrated southeastward and collided obliquely with South America. This collision resulted in the diachronous accretion of allochthonous terranes as well as diachronous formation of a fold and thrust belt. This belt was initiated in the west (Colombia) during the latest Cretaceous and progressively moved east and reached Trinidad only in Miocene time. In front of this thrust belt, diachronous foreland basins developed. The present paper reviews the geologic evolution of northern Venezuela and adjacent areas in the Caribbean Sea, based to a large extent on a huge amount of new data released by oil companies and data collected by universities.

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 fi ssion-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 on July 16, 2015 specialpapers.gsapubs.org Downloaded from 92 V.B. Sisson et al. spe394-03 page 92portion of the subduction complex that has Eocene to Oligocene (42-28 Ma) cooling ages. New fi ssion-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 ultramafi c 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 fi ssion-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 fi ssion-track ages in the Serranía del Interior belt are older than their fossil ages, indicating a Cretaceous minimum provenance age for Miocene beds.Signifi cant new fi ndings 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 signifi cantly 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.

Northern Venezuela consists of a complex series of dismembered east-westtrending deformed belts that defi ne the southern edge of the Caribbean plate. This contribution uses petrologic and geochemical data to defi ne the tectono-magmatic affi liation of some of the belts. These include (1) mid-oceanic-ridge basalts (MORB) included within a mélange composed primarily of passive margin sediments in the Cordillera de la Costa belt, (2) Jurassic sublithospheric mantle and MORB in the Tinaco-Tinaquillo belt, (3) island-arc tholeiites of the Villa de Cura belt, and (4) oceanic island basalts and island-arc intrusive rocks on Gran Roque island, part of the Venezuelan and Dutch Leeward Antilles. Two of the belts (Cordillera de la Costa and Villa de Cura) were metamorphosed in subduction zones then exhumed and thrust onto the margin of Venezuela. The other two belts (Tinaco-Tinaquillo and Leeward Antilles) were obducted onto the edge of Venezuela. These different units record the complex evolution of the Caribbean plate: initial rifting, which formed the protoCaribbean seafl oor (MORB) and Great Arc of the Caribbean, followed by a reversal in subduction polarity caused by the overthickened crust of the Caribbean large igneous province, followed in turn by exhumation and/or obduction of the units and their subsequent emplacement onto northern Venezuela. In the Venezuelan islands, island arc activity continued through the Tertiary.

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