MODELLO

After the December 1999 catastrophic floods in Vargas, an effort was carried out to integrate the geological information of 146 sheets at scale 1:25.000 of the Cordillera de la Costa, covering the Cabo Codera - Morón - Nirgua - El Guapo quadrangle. Simultaneously an inter-institutional agreement was reached to update the names of the igneous and metamorphic units to follow the rules for lithodemic units, therefore all units previous named Group, Formation or Member were changed accordingly. This resulted in a new geological map of the Cordillera de la Costa (Urbani & Rodríguez 2004; Hackley et al. 2004). In previous interpretations the north-central Venezuelan mountains were divided in several east-west trending belts or napes (following Beck 1985 criteria), but due to incomplete geological mapping of the northern Serranía del Litoral its rocks were all lumped into a single "Cordillera de la Costa" nape or belt, but as a result of this new map the region clearly shows its subdivision in three distinct napes which from north to south are: the Coastal Nape (Cretaceous melange probably with older elements, contains bodies of basic rock as eclogites with high pressure - low temperature metamorphism, mainly part of a subduction complex), the Ávila Nape (mainly Paleozoic with Proterozoic elements, with metasediments of passive continental margin environments and abundant granitic to tonalitic gneissic rocks), and the Caracas Nape (Jurassic to Cretaceous passive continental margin metasediments, deposited on Paleozoic granitic basement). The mapping of the southern Serranía del Interior formed by the Caucagua-El Tinaco, Loma de Hierro and Villa de Cura napes was also refined. This configuration poses new constraints to the understanding of the geological evolution of northern South America, and new geochemical and dating work are underway to better understand the unique histories of each nape.