This metallogenic province covers 420,880 km2 (Salas, 190, p. 69–77) and coincides with the huge Mexican Geosyncline, a miogeosyncline extending from Alaska through the western United States and crossing the Mexican border in the vicinity of Ciudad Juarez (Chihuahua) to form the Sierra Madre Oriental.
The Sierra is a chain of elongated mountains formed by large synclines in Jurassic and middle Cretaceous limestones and intercalated clastic sedimentary rocks several thousand meters thick; in some areas (Cañon del Novillo, west of Ciudad Victoria,Tamaulipas) the Mesozoic section is unconformable over Precambrian metamorphic rocks, schists, and gneisses. Figure 1 shows the extent of the province, interrupted at its southern end by the Neo-Volcanic Axis, as seen on the ERTS-1 Satellite image mosaic.
The large folds and faults in Mesozoic limestones trend generally northwest except between Torreon (Coahuila) and Monterrey (Nuevo León) where the Great Mexican Geosyncline deviates at the southern end of the Coahuila paleopeninsula and structures are almost east-west. The hinge of this deviation, trending east-west to northwest, and the Tertiary intrusives, coincide with the Concepcion del Oro Mining District (Zacatecas).