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Late Oligocene Reorganization of the Drainage Divide In Western Gulf of Mexico


The Early Miocene in North America marks a pivotal interval in tectonic activity in which sediment dispersal systems become more localized resulting in a decrease in sedimentation rate to the western Gulf of Mexico. Processes called upon to drive this reorganization include rifting and thermal buoyancy induced uplift. In Northeastern Mexico, observations indicate that basement involved uplift coincident with the Sierra Madre Oriental (SMOr) thrust front is significantly younger than the previously assumed Laramide age (80-40 Ma). Late Cretaceous depositional ages in La Popa and Parras Basin (60-70 Ma) support a brief transit time (10-20 Ma) from the distally sourced Alistos magmatic arc. The minimum detrital age of 42 Ma marks the timing of maximum burial as supported by thermochronological data from Gray et al. 2001. An integration of thermochronological data and detrital zircon basin analysis from the region suggests instead that the inversion of basement structures within and fringing the basins initiated in the Late-Oligocene to Early Miocene. Correlation between the uplift and the decrease in sedimentation rate provides the basis for the alternative explanation for the reorganization of sediment dispersal systems in Mexico. Arc magmatism from the Alistos Arc continued to provide a sediment source due to the associated long standing topographic high in western Mexico. However, thermochronological data, albeit limited, suggests exhumation of the frontal portions of the SMOr. Resulting inversion decreases sediment flux to the Gulf of Mexico during the Lower Miocene by reorganizing the drainage divide within Mexico. The reorganization of the drainage divide, bounded to the east by the SMOr, produced an internal drainage system accommodating sediment shed from the Alistos Arc. Assessing regional seismic reflection profile of the western Gulf of Mexico could provide further insight to the style of depositional systems. Current sediment dispersal systems from the SMOr are facilitated via submarine canyons to the ocean basin, as seen in modern canyons. Decrease in sediment volume during this interval is evident in the Lankahuasa canyon of the western Gulf of Mexico. This Late Oligocene reorganization of the drainage system within Mexico is best supported by the basement involved inversion of the foreland of the Sierra Madre Oriental.