BASIN INVERSION OF MESOZOIC INTRACRATONIC BASINS OF NORTHERN MEXICO AS A PRINCIPAL CONTROL OF LARAMIDE FOLD BELTS

Structural mapping throughout Northern Mexico has documented basin inversion as the principal mechanism of fold belt development in the region. The mapping includes parts of the Chihuahua-Sabinas-La Popa series of basins in northeast Chihuahua through central and southeast Coahuila and the Bisbee-Carrizal-San Juan de Gallo-Parras series of basins of central Chihuahua, northeast Durango and southern Coahuila. The two belts of basins are separated by the Florida-Aldama Platform to the north and the Coahuila Island to the South. All of these basins apparently developed as Late Triassic intracratonic extensional basins and contain thick sections of Jurassic volcanic, clastic and evaporite fill. Thrusting out of the basin onto the platforms was produced during east northeast directed shortening of these basins during the Late Cretaceous through early Tertiary. Where these thrusts extend upon less deformed platform sediments locates the margins of the basins and fault bend folds on the leading edges of the thrust sheets document the direction of thrusting. Along exposed basin margins, out of the basin thrusting occurs as north to east directed thrusting on the north to east margins of the basins and on the less well documented western and southern margins of the basins, west to south directed thrusting occurs. This distribution of thrusts out of the basins supports a model of basin inversion as the principal source of Mexico's northern Sierra Madre Oriental fold belts as opposed to the regional sole detachment and folding at the eastern margin of the detachment surface. The complex configuration of fold belts observed in Northern Mexico can be best explained by the basin inversion model.