Abstract: Generative Systems And The Geodynamic Evolution of the Gulf of Mexico

Guzman-Vega, Mario Alberto; Roberto Bertrand-Camargo; Lilia Castro-Ortiz- IMP, Mexico

Tectonic evolution of the Mexican Gulf Coast has been a main control of the generative systems and their physico-chemical variations. Geodynamic history of this area involves three tectono-stratigraphical stages: rift, sag and passive margin.

Generative systems of the rift stage were related to anoxic marine carbonate environments from Oxfordian until Tithonian times. Subtle variations in salinity, oxygen depletion levels, clay and carbonate content in these environments can be identified by the molecular features of their related oil and organic extracts. Tithonian oils have a widespread distribution throughout the western and southern Gulf of Mexico. Marine carbonate evaporitic environments were developed during the sag stage from Neocomian until Middle Cretaceous times. The oils related to these environments were dominated by a strongly prevailing bacterial input They are present in the Veracruz Basin and the Chiapas-Tabasco area. Deltaic organic-rich environments were related to the passive margin stage from Paleocene until Miocene times. Oils generated from these facies are geographically limited to the Burgos and Macuspana basins. Their molecular features suggest a source from reworked, bacterially degraded terrestrial higher plants deposited in siliciclastic dysaerobic depositional environments.