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Seismic Interpretation of the Laramide Submarine Fan, a Lower Tertiary Wilcox Trend in the Deepwater Mexican Gulf of Mexico, and Implications for Hydrocarbon Potential


The Lower Tertiary Wilcox trend has become a major hydrocarbon play in the U.S. Deepwater Gulf of Mexico (GOM) and is estimated to have as much as 15 billion barrels of oil equivalent in reserves. Recent Wilcox crude oil discoveries such as Buckskin, Cascade, Great White, Jack/St. Malo, and Tiber have only tapped the surface of the hydrocarbon potential that awaits this frontier play, and much of the trend has yet to be explored. For the past several years, crude oil discoveries of the Lower Tertiary Wilcox trend have only been found in the U.S. Deepwater GOM. However, in late 2012, Petroleos Mexicanos (Pemex) made their first discovery of crude oil in the Deepwater Mexican Gulf of Mexico (MGOM) with their Trion-1 well in the southern extent of the Perdido Passive Margin Foldbelt, with estimated 3P reserves of 250-400 MMboe in these Wilcox-equivalent sediments. The U.S. Rocky Mountains have long been recognized as the provenance for the Lower Tertiary Wilcox trend in the western GOM. This study proposes an additional source of Wilcox-equivalent sediments from the Sierra Madre Oriental Fold-and-Thrust Belt (SMOFTB) during the Laramide orogeny in central Mexico (Late Cretaceous to late Eocene). The Laramide Submarine Fan derived from this orogenic phase spans the entire western GOM (U.S. and Mexico) and is ∼500 km wide and ∼3.5 km thick (∼310 mi wide and ∼2.2 mi thick). Late Cretaceous to Paleogene eastward-directed thrust sheets along the SMOFTB are consistent with other Laramide deformation features in North America and correspond to the southernmost extent of the Cordilleran orogenic belt. Basement-involved reverse faults due to inversion of rift structures along the MGOM coastline and shelfal areas also suggest Laramide-aged, thick-skinned compression. Backstripping of five offshore wells from Campeche Bay to Tampico-Misantla and across into the Sigsbee Escarpment show a major pulse of subsidence at ∼66 to ∼40 Ma inferred to be the onset of Laramide-related foreland basin tectonics, with the strongest indication of subsidence evident in the offshore Tampico-Misantla region. The proximity of the SMOFTB (∼200 km, or ∼124 mi) to the MGOM compared to the U.S. Rocky Mountains (1500-2000 km, or ∼930-1240 mi) in addition to the timing of Laramide orogeny in central Mexico supports a foreland basin wedge, the Laramide Submarine Fan, splaying outboard into the western GOM.