The Ouachita system in northern Mexico can be subdivided into four unique tectonostratigraphic provinces: the foreland, the frontal zone, the interior zone, and the Coahuila terrane. Each province is defined by specific lithologic characteristics, structural styles, and regional Bouguer gravity anomalies. The Ouachita foreland is characterized by a carbonate dominated shelf which was disrupted during the late Paleozoic by several basement cored uplifts. The frontal zone is a northwest migrating foredeep and fold‐thrust be clastic sediments derived mainly from the fold‐thrust belt filled the foredeep and were subsequently deformed as the fold‐thrust belt migrated. The interior zone is the metamorphic core of the migrating fold‐thrust belt and is characterized by a distinctive positive Bouguer gravity anomaly. The Coahuila terrane is a composite terrane which includes a late Paleozoic volcanic arc and a piece of exotic continental crust which was probably afixed to North America during the final stages of the Ouachita orogeny and then left behind during the opening of the Gulf of
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