Structural and tectonic evolution of western Cuba fold and thrust belt

摘要

We present balanced and restored cross sections across the western Cuba fold and thrust belt to illustrate its structure and tectonic evolution, based on the interpretation of multichannel seismic profiles, field data and balancing techniques. The NNW-SSE trending Soroa cross section intersects, from south to north, (1) the Los Palacios Basin, (2) the Sierra del Rosario antiformal stack, (3) the Bahia Honda thrust unit, (4) the frontal ～3-km-thick imbricated thrust sheets, and (5) the foredeep basin. At depth, a duplex that links the Sierra del Rosario unit and the frontal imbricates is defined using the thickness of the cover thrust sheets of the imbricated North American margin. The minimum calculated shortening is of 130 km in a SSE or south direction to fit large-scale plate tectonic reconstructions. However, a more allochthonous alternative using thinner cover sequences is also discussed, which restores the Bahia Honda unit 220 km to the south of its present position. Syntectonic deposits in combination with a forward kinematic model provide a good constraint for the tectonic evolution of the orogen. The internally deformed Bahia Honda unit overthrusted the North America margin cover successions during Danian and Selandian times (～65.5-60 Ma), before the stacking of these cover rocks during Selandian and Thanetian times (～60-56 Ma). The growth of a large antiformal stack beneath the Sierra del Rosario occurred at early middle Eocene (～56-45 Ma), generating about 4 km of structural relief between the paleoisland of Cuba and the synorogenic seafloor before the final infill of the foredeep.