Source Rock Systems of Mexico

Noel Holguin, Federico Galindo, Anunziata Romero, Enrique Serrano, Gustavo Martinez, Alejandro Sosa

Oil production in Mexico is restricted to six basins related to the Gulf of Mexico megaprovince. According to their importance they are the Sureste, Tampico-Misantla, Burgos, Veracruz, Sabinas and Sierra de Chiapas Basins.

Tertiary source rocks have been identified in Burgos, Veracruz and Sureste Basins according to geochemical data. In the Burgos Basin siliciclastic marine deltaic rocks of Paleocene-Eocene age are the source rocks with Kerogen type III. In the Sureste and Veracruz Basins the source rock is Miocene.

Lower Cretaceous evaporitic calcareous facies with Kerogen type II in the Sierra de Chiapas and Veracruz Basins are the hypothetical source of the oils in those basins.

The Tithonian rocks are the most prolific source in Tampico-Misantla and Sureste Basins. It is estimated that they have generated more that 90% of the known crude oil reserves of Mexico. Marine laminated shaly limestones and shales are thick and rich in organic matter. They are mature in the Sureste and Tampico-Misantla basins. In the rest of the basins they are overmature.

Biomarkers and isotopic data indicate that laminated limestones of Oxfordian age with Kerogen type II are the source rocks for the oils discovered in some offshore fields in the Sureste Basin.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995