Abstract

Plate tectonic models of the Gulf of Mexico are highly dependent on pre-rift plate configurations and subsequent kinematics of the Central Atlantic, South Atlantic, and Florida. We developed a new plate model for the Mesozoic evolution of the Gulf of Mexico by constraining these important boundary conditions. Geologic and geophysical observations from the Central Atlantic, South Atlantic, and eastern Gulf of Mexico were integrated using 3D visualization tools and non-rigid plate reconstruction software that allows rapid multiple scenario analysis. The pre-rift configuration of tectonic plates is constrained by palinspastically restoring both isostatic models of continental crust and refraction lines from eastern North America, West Africa, and Morocco. Where clear magnetic lineations and fracture zones are not present the motion of microplates is quantitatively linked to the motion of large-scale plates by assuming a seafloor-spreading propagation model. Our preferred model does not require fragmentation of Florida along the proposed Bahamas transform fault. Instead, Florida is modeled as a coherent block that underwent counter clockwise rotation primarily during Triassic time. Major rotation of the Yucatan Block began around 176 Ma in response to the propagation of seafloor spreading into the Proto-Caribbean Sea. The full spreading rate in the western and central Gulf of Mexico is predicted to be less than 1.5 cm/yr prior to the Callovian. This suggests that most of the material typically thought to be highly extended continental crust in the deepwater regions of the northern Gulf of Mexico may be new ground composed of ultraslow spreading lithosphere.