This study will address the tectonic evolution of St. Croix during Cretaceous and Cenozoic times in order to obtain constraints on the tectonic evolution of the northeastern Caribbean region and the Caribbean - American plate boundary zone. Cretaceous sedi- mentary rocks on St. Croix will be analyzed to determine their age range, environments of deposition, determine their age range, provenance, ages of metamorphism, and the geometry and kinematic development of the tectonic complex they occupy. Syntectonic igneous dikes, sills, and plutons will also be studied to determine their age range and relationship to the developing tectonic complex. The geometry and kinematics of the Cenozoic graben on St. Croix will be examined and its relation to regional extension in the NE Caribbean ascertained. St. Croix differs from nearby islands in that it is the only subaerial exposure of bedrock between the Puerto Rico - Virgin Islands platform and the Venezuelan Basin. Resolution of the tectonic history of St. Croix as a result of this study will form an essential component in our understanding of the tectonic evolution of the NE Caribbean. The results will also have important implications for understanding the tectonics of major plate/micro plate interactions.
