| The island of Bequia lies in the southern section of the Lesser Antilles arc, which formed along the eastern margin of the Caribbean plate, where it is being under-thrust by the subduction of Jurassic to Cretaceous Atlantic oceanic lithosphere.; Plutonic cumulate blocks were collected at single sites from each of the three volcanic formations; plutonic blocks labeled BQ60, were collected from the Northern Peninsular Formation, along outcrops on northern coast of Bequia. Blocks labeled BQ45, were collected from the Mount Pleasant Formation in the central area of Bequia. Blocks labeled PN, were collected from the Southern Peninsular Formation on Petit Nevis. All of the blocks collected at each location occur together in a single epiclastic or pyroclastic unit, and are considered to have erupted together and provide a “snapshot” of the physical and chemical conditions in the magma chamber. Each suite of blocks is characterized by distinct mineralogical and compositional features, which are indicative of the crystallization processes occurring within the magma chamber. (Abstract shortened by UMI.)... |
