NEOGENE EVOLUTION OF THE NORTH CARIBBEAN PLATE BOUNDARY FROM CAYMAN TROUGH, SOUTHERN CUBA TO HISPANIOLA

Correlations of sedimentary units and deformations in the basins of southern Cuba, central Haiti, and the northern Dominican Republic provide good records of the Neogene evolution of the North Caribbean Plate Boundary between Cuba and Hispaniola.

From Late Cretaceous to Lower Miocene, the geologic formations on both southeastern Cuba and Hispaniola show analogous sedimentary, tectonic and magmatic evolution: between Upper Eocene to Lower Miocene, the Maquey Fm of SE-Cuba and the Altamira Fm of Tabera Gp of Dominican Republic are both deposited in a basin isolated from major oceanic circulations. Thus, until the end of Lower Miocene, southeastern Cuba and Hispaniola has the same tectonic, stratigraphic and magmatic evolution. The history of both domains begun to differ from the end of Lower Miocene. In the southern coast of Cuba, the Imias formation shows marine facies deposited on open oceanic conditions, with spectacular large-scale oblique stratifications indicating a sedimentation along a long-term south-facing slope, enhancing the development of the present-day Oriente Fault. In Haiti and Dominican Republic, this period is marked by the sedimentation of several limnic formations.

The reconstitution of the history of the opening of Cayman Trough is in agreement with this evolution. There is indeed a significant structural reorganization of Cayman Trough opening at this time, as shown by the brutal change of direction of magnetic anomalies and tectonic structures, roughly N45° before 20Ma and N-S, perpendicular to both side of the present-day Cayman Trough after.

Another major reorganization of the plate boundary zone occurs during Lower Pleistocene (2/1.8 Ma), with the uplift of the Dominican Septentrional Cordillera and the development of the present day Septentrional Fault across the northern DR. The detailed morphology of the Windward passage and the submarine area in front of southeastern Cuba (Punta Caleta) records this tectonic reorganization.

This area shows well developed geological formations, distributed along more than 500km in the direction of the major left-lateral strike-slip fault, from west to east: more detailed studies of these basins and of their successive opening could provide a unique record of the rate of propagation of a major fault along this plate boundary.