Structural Evolution of the Southern Lesser Antilles Arc

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Models of Caribbean tectonic evolution generally indicate a Paleogene Lesser Antilles arc and a spatially identical successor Neogene arc above the leading edge of the Caribbean plate throughout much of the Cenozoic, implying east-west convergence for most of their time period. However, recent findings in Grenada and the Grenadines indicate that the pre-Neogene rocks experienced north-south compression prior to onset of arc magmatism related to westward subduction of the Atlantic below Caribbean lithosphere. This research will test an alternative hypothesis that the earlier deformation was related to a discrete southern Lesser Antilles arc that accommodated north-south convergence between the North American and South American plates prior to the arrival of the Caribbean plate from the west in the Miocene. The work will include field structural mapping, study of existing marine seismic data, petrology and paleomagnetic data. Results will be of considerable importance in understanding Cenozoic interactions between the North American, South American and Caribbean plates.