El origen del Golfo de MéXico y de sus subcuencas petroleras Mexicanas, con base en la palinoestratigrafía de Lechos Rojos

Some Mexican Mesozoic red bed sequences have recently been dated using the palynostratigraphical method, developed at the Mexican Petroleum Institute in 1975. Some of them are the economic basement of the Mexican petroleum Gulf of Mexico sub-basins, and they represent the beginning of the Mesozoic marine transgression which formed the petroleum systems. The palynostratigraphical method is based on the macro- and microscopic analysis of the organic and inorganic components from the palynological residue, and also from the glycerinated alcohol in which it is preserved. This analysis allows one to obtain litho-, bio-, and chronostratigraphical data related to tectonosedimentary, and diagenetical processes. The information obtained from the red beds Los San Pedros Allogroup and Huayacocotla Group (Rhaeto-Liassic age in the Huayacocotla-El Alamar Basin), La Joya Formation (Middle Jurassic in the Sabinas sub-basin), Rosario and Cahuasas Formations (Middle Jurassic age in the Tampico-Misantla sub-basin) and Todos Santos Formation (Middle Jurassic age in the Veracruz and Chiapas-Tabasco-Campeche sub-basins) permitted the construction of a model for the origin and evolution of the Gulf of Mexico which is very useful to understand the development of the Mexican petroleum accumulations. The model includes basically three different times: (1) the formation of one or two Rhaeto-Liassic wrench or shear basins (Huayacocotla-El Alamar Basin) related to the evolution of a Pacific Plate convergent system; (2) during the late Liassic, the origin of the Tampico-Misantla sub-basin as a result of the southwestern displacement of the Huayacocotla and Tlaxiaco blocks by means of the Tampico-Lázaro Cárdenas and Teziutlán-Acapulco megashears; and (3) during the Middle Jurassic time, the origin of the Gulf of Mexico Basin and the Mexican petroleum Sabinas, Veracruz and Tabasco-Chiapas-Campeche sub-basins related to a triple junction system, which permitted the movement of the Chiapas-Tabasco-Campeche-Yucatán block to the southeast following the Pico de Orizaba-Juchitán-Laguna Superior Megashear.