Basement Characterization and Tectonic Evolution of the Guajira Peninsula

Abstract

The Guajira Peninsula lies at the interaction of the overriding Caribbean and stable South American plates, an area characterized by a unique geologic setting. A recent geochronology study of both offshore and onshore basement in the Guajira Basin gives new light to the structural evolution of the area during late Cretaceous and Cenozoic times. Studied samples from wells and outcrops, confirms the lithological correlation between northern Guajira Ranges and Santa Marta Massif, Lower Magdalena Basin and Western, Central and Eastern Colombian Cordilleras. These ranges represent an igneous and metamorphic belt with a complex structural history driven by obduction, subduction, accretions and strike slip due to the Caribbean plate motion along northwestern South America (NWSA) during the Cenozoic. The Caribbean oceanic plate collided with the northwestern edge of Guajira Peninsula at the end of the Cretaceous producing obduction (landward-vergent accretion) of volcanic arc terranes along this margin. After this collision, the Caribbean plate began its subduction under South America, stretching and pulling apart the overlying rocks in an approximate west to east direction giving rise to the Tayrona and Rancheria extensional basins along the Offshore Guajira area. At the regional scale the extension along the NWSA margin pulled apart the Colombian Cordilleras from Santa Marta Massif and Guajira Ranges. The dated basement samples provide evidence of this collision and the boundary between the landward accreted allochthonous basement terranes and the South America autochthonous basement terranes. During the late Miocene, the collision of the Panama arc against NWSA induced the displacement of Maracaibo and Bonaire microplates towards the northeast, overriding the Caribbean plate and enhancing the structure of the Southern Caribbean Deformation Belt (SCDB), a seaward-vergent accretionary prism. The two described tectonic accretions generated compressional structures but between them deep Cenozoic extensional structures remain in the Tayrona and Rancheria sedimentary basins offshore Guajira. Some of these structures are still active today due to the continuous movement of the Caribbean plate to the east. The presence of Cretaceous strata and the implication for the petroleum system of the area have been discussed recently in relation to renewed petroleum exploration in these basins. This basement study may help to understand the existence of effective source rock along these basins.

AAPG Datapages/Search and Discovery Article #90330©2018 AAPG Hedberg: Geology of Middle America – the Gulf of Mexico, Yucatan, Caribbean, Grenada and Tobago Basins and Their Margins “Integration of the geology of the area from the southern onshore of North America to the northern onshore of South America”, Siguenza, Guadalajara, Spain, July 2-5, 2018