Provenance of the Upper Cretaceous-Paleogene Difunta Group in the foreland basin system of the Sierra Madre Oriental, Mexico, and its implication for sediment fairways in the Gulf of Mexico

U-Pb ages of detrital zircons from the Difunta Group in the Parras and La Popa basins of the Sierra Madre Oriental foreland reveal a unique provenance signature that may prove useful in deciphering sediment-dispersal systems for Paleocene Wilcox sands in the deep Gulf of Mexico. Petrography and U-Pb age distributions in 12 samples from 6 sandstone units ranging in age from Maastichtian-middle Eocene in La Popa Basin (1,112 individual zircons) and correlative strata in the neighboring Parras Basin (200 zircons) indicate that sediment delivery to the basins changed little over 30 m.y. In combination with paleocurrent and paleogeographic information, the zircon age distributions indicate long-distance sediment delivery from the west and northwest. Proterozoic grain populations at 1.7, 1.4, and 1.1 Ga indicate that a main trunk river likely originated in the SW United States and flowed southeast parallel to the front of the Sierra Madre orogen. Jurassic, Cretaceous, and Paleocene zircons were delivered via east-flowing tributaries from arc terranes of western and NW Mexico that likely included the Jurassic Cordilleran arc, the Early Cretaceous Alisitos arc, and the Late Cretaceous-Paleogene Peninsular Ranges batholith of the Baja Peninsula. Although Late Cretaceous rivers had deltaic termini within the foreland basin, Paleogene sandstones continue eastward toward the Gulf of Mexico beyond the limit of outcrop.

The deepwater Paleocene Wilcox Formation in the Gulf of Mexico is a major hydrocarbon play, but some controversy exists as to the source of Wilcox sands, which are difficult to track beneath allochthonous salt. Paleogeographic models predict that the zircon signature of the northeastern Mexico sandstones should be significantly different from those of other deltaic systems active along the Gulf of Mexico during the Paleocene. Thus, detrital-zircon characteristics of the deepwater Wilcox may help delineate the entry point of those sandstones into the deep Gulf.