Undiscovered Oil and Gas in Mexico, Belize and Guatemala, 2024 USGS Assessment

The U.S. Geological Survey assessed how much undiscovered, technically recoverable conventional oil and gas may lie in 14 assessment units (AUs) within nine geologic provinces of Mexico, Belize and Guatemala: the Burgos Basin, Tampico-Misantla Basin, Veracruz Basin, Campeche-Sigsbee Salt Basin, Saline-Comalcalco Basin, Villahermosa Uplift, Macuspana Basin, Yucatan Platform, and Sierra Madre de Chiapas-Petén Fold Belt.

The results

F95 means a 95 percent chance of at least that amount; F5 a 5 percent chance. The results are fully risked estimates.

The assessment units: (A) six in Mexico and (B) eight in Mexico, Belize and Guatemala. USGS.

How the basins formed

The region's oil and gas are the product of a complex tectonic history:

• Rifting. From the Triassic to the Early Jurassic, North America, the Yucatan Platform and South America began pulling apart as Pangaea broke up, leaving rift basins filled with river, alluvial-fan and lake sediments, possibly including source rocks, reservoirs and traps.
• Salt. Intermittent access to the ocean in the Middle Jurassic (Bajocian), and possibly as late as the Callovian, laid down as much as 2,000 meters of salt. As rifting waned, organic-rich source rocks of Oxfordian, Kimmeridgian and Tithonian age settled on top; Oxfordian sandstones and carbonates on the western Yucatan Block may resemble the Norphlet and Smackover reservoirs of the eastern U.S. Gulf Coast.
• Seafloor spreading. Beginning in the Oxfordian, the Yucatan Platform rotated counterclockwise, splitting the salt into the Louann basin on the U.S. margin and the Campeche basin off the Yucatan Block, where buried salt deformed into many traps. Spreading ended when the Yucatan Block stopped moving, by Valanginian time.
• Carbonate platforms. Under open-marine conditions, repeated advances and retreats of the sea built stacked carbonate platforms along the Burgos, Tampico-Misantla and Veracruz margins and around the Yucatan Block, with reservoirs in karst, dolomite, reefs, mounds and debris-flow deposits.
• Mountain building and sediment. Subduction along Mexico's western margin folded and thrust rocks into fold belts with fractured carbonate reservoirs. Their uplift and erosion shed thick sediment eastward offshore, creating reservoirs and traps and keeping the Campeche salt moving, which could alter structures and breach seals. In the Paleogene, the Greater Antilles arc moving north inverted structures on the southeastern Yucatan margin, possibly losing oil and gas. In the Miocene, slides along overpressured Eocene shales built the offshore Mexican Ridges Fold Belt, and salt withdrawal on the southern Yucatan margin opened the Macuspana and Saline-Comalcalco basins, which filled with Miocene to Pliocene sediment.

Source rocks and assessment units

All 14 AUs belong to one Mesozoic–Cenozoic Composite Total Petroleum System. Most of the oil and gas is credited to organic-rich shales of the Oxfordian Smackover and Tithonian Pimienta formations, with contributions from Triassic lake shales, Kimmeridgian marine shales, Albian marls, Cenomanian–Turonian marine shales and younger marine and terrestrial shales; not every source is present in every province.

Oil accumulations also hold gas and natural gas liquids, and gas accumulations hold liquids; the full breakdown is in USGS Fact Sheet 2025–3040 and its data release.

Sources

Rewritten from U.S. Geological Survey Fact Sheet 2025–3040, "Assessment of undiscovered conventional oil and gas resources in Mexico, Belize, and Guatemala, 2024," by the USGS Mexico, Belize and Guatemala Assessment Team (public domain), in hubnx's own words. The fact sheet attributes the Sierra Madre de Chiapas Fold Belt both to Late Cretaceous–Eocene subduction of the Farallon plate and to Miocene subduction of the Cocos-Nazca plate; the page dates it to neither.