Geology and mineral resources in the Cornudas Mountains, Otero County, New Mexico and Hudspeth County, Texas

Abstract

The Cornudas Mountains form the northern part of the Trans-Pecos magmatic province in southern New Mexico and northern Texas. Ten larger intrusive bodies and numerous dikes, sills and smaller plugs have intruded Permian and Cretaceous limestones and other sedimentary rocks. The intrusives range in age from 33 to 36 Ma. The Cornudas Mountains have been examined for potential economic deposits of gold, silver, beryllium, rare-earth elements, niobium and uranium but no economic deposits have been found. However, Addwest Minerals, Inc. recently began exploration and development of the Wind Mountain nepheline syenite for use in amber-colored beverage containers and ceramics. Production is expected within a few years. The Cornudas Mountains alkalic igneous rocks form the eastern limit of a progressive change from alkalic-igneous rocks in the eastern Trans-Pecos magmatic province to less alkalic and calc-alkalic igneous rocks in western Trans-Pecos Texas, Mexico and southwestern New Mexico. This change in magmatism corresponds in time to the transitional interval between Laramide compressional tectonics and younger Basin and Range extensional tectonics. Great Plains Margin gold-silver deposits (i.e., alkalic-related gold deposits), including those elsewhere in New Mexico and along the North American Cordilleran alkalic-igneous belt, appear to be related to back-arc extension, hot spots and complex, multiple cycles of magmatic differentiation resulting in both alkalic and calc-alkalic igneous rocks. If these constraints are required to form Great Plains Margin gold-silver deposits, the Cornudas Mountains may be unfavorable for such deposits.