GEODYNAMIC EVOLUTION LATE EOCENE-OLIGOCENE IN THE BURGOS BASIN, MEXICO

The Mexican Fold and Thrust Belt deformation left a print in the stratigraphic successions at the Burgos Basin. The foreland facies appear in the Turonian age at Zacatecas, migrated eastwards appearing in the Thanetian at the Burgos Basin, where the Wilcox-lower Yegua (Crockett Formation) represent foreland prograding highstand facies (Lower to Middle Eocene). The base of middle Yegua (sensu PEMEX) is a sequence boundary linked to the end of an orogenic event in Mexico (~39.5 Ma), structural data in the Sabinas Basin (⁴⁰Ar/³⁹Ar ~41-40 Ma) support this hypothesis. The Yegua-Jackson deposits (Bartonian-Priabonian) are numerous transgressive and regressive high frequency cycles, erosive surfaces, and chaotic structures observed in seismic data showing a huge siliciclastic source derived from the continental erosion towards the Gulf of Mexico. Down slope flow of erosive currents from Yegua-Jackson could have induced an erosive submarine canyon at south of the Burgos Basin. Both formations accumulated more than 4500 m of sediment thickness in shelf margin and slope basin, on structural blocks next to expansion normal faults, that sediments bypass coastal plain facies up dip basin. On those blocks the Jackson Formation has ~2500 m thickness and sediment rates high accumulated in 1.6 Ma (~0.15 cm/year), higher than the Wilcox deposit (~1200 m in 8.8 Ma). The Jackson top is a sequence boundary at ~33.9 Ma, age coincident to start the tectonic slab regression at deep crustal, and an isostatic uplift from the Tamaulipas Arch could pull-apart the Sabinas and Burgos basins. The Vicksburg Formation is a transgressive-regressive succession (Oligocene), a thick deposit (~3000 m) it was formed in short time (~6.5 Ma). At the top of this formation exists a relevant regional disconformity (~23.9 Ma) and a molasse deposit (Norma Formation) lies on it, these features possibly link the exhumation of the Orogenic Belt of Mexico (<30 Ma). The Ahuichila Formation at central Mexico is a molasse continental deposit, U-Pb zircon detrital and tuff dating suggest their age ~28-24 Ma, but their deformation is possible to be associated with basement faults, a similar style of deformation is observed on the Coahuila Block and San Julian Uplift, deformation that is possible linked toward the sedimentation on the top of the Vicksburg Formation.