The stratigraphy of south-central New Mexico
Greg H. Mack, Frank E. Kottlowski, and William R. Seager
South-central New Mexico contains rocks of Precambrian, Paleozoic, Cretaceous, and Cenozoic age exposed in late Cenozoic fault-block mountains and adjacent basins. Precambrian (upper Proterozoic) metamorphic rocks and granites are unconformably overlain by a sequence of Upper Cambrian through Mississippian marine carbonates and minor sandstones and shales about 1 km thick. Late Paleozoic deformation associated with the Ancestral Rocky Mountains created the Pedernal uplift and complementary Orogrande Basin, in which were deposited approximately 2 km of Pennsylvanian and Permian mixed marine and nonmarine siliciclastic and carbonate strata. Lower Cretaceous siliciclastic and carbonate sediment approximately 500 m thick was deposited in an extensional basin (Chihuahua trough) in the southernmost part of the area, and about 1 km of Upper Cretaceous siliciclastic sediment, preserved locally in the northern part of the region, was deposited in the Western Interior foreland basin. Andesitic rocks were emplaced along the western margin of the study area, representing the easternmost spread of a Late Cretaceous continental arc in the Southwest. Latest Cretaceous (Maastrichtian) and early Tertiary (Paleocene and Eocene) compressional deformation associated with the Laramide orogeny produced a northwest-trending, basement-cored uplift and complementary basins, in which were deposited about 1 km of nonmarine siliciclastic detritus, followed by andesitic volcanism. Extension in the Rio Grande rift began in the Oligocene with minor block faulting and voluminous bimodal volcanism, including eruptions of the Organ and Dona Ana cauldrons, and was followed in the Miocene by block faulting and deposition of about 1.5 km of primarily siliciclastic detritus. Several hundred meters of sediment and minor basalt were deposited during the most recent stage of extension of the Rio Grande rift, which began in latest Miocene and Pliocene time and is responsible for the present distribution of basins and uplifts.
- Mack, Greg H.; Kottlowski, Frank E.; Seager, William R., 1998, The stratigraphy of south-central New Mexico, in: Las Cruces Country II, Mack, G. H.; Austin, G. S.; Barker, J. M., New Mexico Geological Society, Guidebook, 49th Field Conference, pp. 135-154.