Isla Margarita (Venezuela) represents a compositionally heterogeneous piece of crust located at the southern margin of the Carribean plate. It is composed of peridotites, metamorphic units, various types of magmatic rocks and sedimentary cover.
The late igneous rock suite on Margarita is a series of Eocene lamprophyric dikes and small gabbroic intrusions. Geochemically the Margarita igneous rocks are basaltic to andesitic in composition, although overall high compatible element concentrations
are striking and together with intermediate compositions suggest fractionated magmas from large percentage mantle melts. Variable enrichment in trace and light REE elements, as well as high radiogenic strontium and lead isotopic ratios, imply an
additional subduction zone component.
The origin of the magmas and timing of emplacement are important clues for unravelling the tectonic history at the southern margin of the Caribbean plate and testing of plate tectonic scenarios.