MODELLO

Proposed in 1993, this model is based on redbeds and salt palynostratigraphy data obtained from Mexican Oil Basins, since 1975, considering that there are not tectonic evidences of Jurassic displacement of Chiapas-Yucatán sub-plate to SE, as generally considered.
The initial RRR triple junction system was formed during Late Liassic near NE Tampico by the SE-NW Texas-Boquillas-Sabinas, the SW-NE Campeche Escarpement and the N-S Nautla-Pico de Orizaba arms, where the Texas-Louisiana, Western Region of Mexico, and Chiapas-Yucatán subplates came together. Because the last one was joined to South American plate, it was stable during Jurassic, and only Texas-Louisiana and Western Region of Mexico subplates were displaced northwestward, the first one faster than the second one; the Texas-Boquillas-Sabinas arm became a megashear zone, parallel to the southern Chihuahua-Sabinas graben. So, the original RRR triple armed graben formed two masses with a predominantly ridge boundary, and a failed arm of a ridge forming a trough. This displacement was possible, due to the formation of the NW-SE Pico de Orizaba-Laguna Superior megashear, and to the reactivation of the NW-SE Vancouver-Bahamas megashear; and also because a subduction zone existed in the Pacific border of the North-American Plate. This motion allowed the Campeche Escarpement and Nautla-Pico de Orizaba arms became wider ridges and seafloor spreading zones, where the Gulf of Mexico formed.
The northwestward motion of the Texas-Louisiana subplate, bordered by the Texas-Boquillas-Sabinas and Vancouver-Bahamas megashears, at present in Canada and Mexico frontiers, originated the 800 km displacement of the Ouachita System and it is related to tectonic phenomena in the Pacific subduction region, as a very active compressive zone during Jurassic-Eocene time (main Cordilleran orogeny).
After Jurassic time, North and South America cut into two separate plates; Cuba blocks, from N Venezuela and Guyana, and Chortis block, from S Mexico, began to move up to their present places in the Caribbean Plate.