GEOLOGY AND INDUSTRIAL MINERALS OF NORTHEASTERN MEXICO

The northeastern region of Mexico, which includes the States of Coahuila, Nuevo Leon y Tamaulipas, is located south of Texas. It is Mexico’s largest industrial-mineral-producing region. The area consists mainly of marine sedimentary rocks and lies in three geological provinces: the Mesozoic Mexican Folds and Faults Belt province, the Cenozoic Gulf of Mexico Geoclinal province and the Mesozoic Coahuila Platform province.

The Mexican Folds and Faults belt province is made up of Permian carbonate rocks, Triassic continental red beds, Jurassic evaporites, and Cretaceous carbonate rocks. This entire sequence, greater than 3,500 m in thickness, was subject to folding, thrust-faulting, and block-faulting during the Laramide Orogeny, giving rise to typical basin-and-range topography. Scattered Tertiary clastic sediments and volcanics are also present. Industrial mineral deposits that occur in the province include Jurassic gypsum and phosphate, Cretaceous limestone and dolomite, and Tertiary barite and sodium sulfate/sodium chloride.

In contrast, the Gulf of Mexico Geoclinal province consists mainly of Cretaceous to Holocene sedimentary rocks. These rocks have been moderately to highly folded and faulted. Sedimentation ranges from calcareous to silisiclastic. The major industrial minerals present are Jurassic salt/gypsum, Cretaceous limestones and dolomite and Eocene silica sand. Tertiary alkaline intrusives rocks containing nepheline syenite are also present.

The Coahuila Platform province is comprised predominantly of Permian to Holocene sedimentary rocks. In general terms, the stratigraphy is very similar to the mexican Folds and Faults Belt province. The main difference is that Triassic and Jurassic sections are nearly absent. Industrial-minerals deposits include Cretaceous celestite and tertiary fluorspar, barite, and sodium sulfate.