STRIKE-SLIP FAULTS AND TRANSFORMS: KEYS TO PLATE TECTONIC PROCESSES DURING EVOLUTION OF THE CARIBBEAN PLATE

In southwestern Puerto Rico (PR) allochthons of serpentinite moved southwestward across commonly steeply tilted Maastrichtian-Paleocene strata before Oligocene. The contraction is kinematically related to east-striking sinistral faults. These faults, as well as other sets of strike-slip faults with different ages and orientations, and subduction-related magmatic belts constrain plate models. The inferred east-striking sinistral faults of PR, which are interpreted to link westward with faults along the Cayman trough, became active after intrusion and cooling (~50-45 ma) of calc-alkaline plutons in SE Cuba. Restoration of about 400 km along the east-striking Oriente fault zone and related deformation belts brings Eocene and Paleocene rocks in Hispaniola, PR and Virgin Islands close to those of Oriente province, Cuba. PR and Virgin Islands may be restored close to disrupted strata of the Peralta Group, interpreted as part of an accretionary prism, in southeastern Hispaniola by ~300 km of motion along an eastward extension of the Enriquillo-Plantain Garden fault. The restoration distinguishes a domain of Eocene calc-alkaline igneous rocks restricted to the south-southwestern margin of the eastern Greater Antilles (GA). The inferred movements also translate the Nicaragua Rise westward thereby revealing a pathway along which Pacific oceanic lithosphere may have moved hundreds of kilometers ENE and subducted beneath the southern flank of the pre-existing Cretaceous GA magmatic belt before 44 Ma. The northward-directed Eocene subduction followed Early and Late Cretaceous magmatism that resulted from southward-directed subduction leading to plate collision and coupling of the GA belt against the Bahama platform. Collision was followed by development of NE-striking sinistral faults that segmented Cuba progressively (?) from west to east. The Cuba-Bahamas collision was contemporaneous with collision of Chortis against the southern margin of the Maya block suggesting linkage by a trench-trench transform along eastern Yucatan. Similarities between Late Jurassic and some older Cuban rocks and those of Yucatan and/or Chortis indicate that the most straightforward path of the GA into the Caribbean is from SW to NE parallel to the transform.