New Mexico Geological Society Annual Spring Meeting — Abstracts

Immediately east of the Coronado Golf course above the western boundary normal fault basal Permian Hueco conglomerate and sandstone unconformably overlies faulted and deformed Early Pennsylvanian through Silurian age rocks. This conglomerate is similar in appearance to the basal Permian Powwow Conglomerate in the Hueco Mountains. The conglomerate contains large clasts ofrounded Silurian Fusselman Dolomite suggesting the Southern Franklin Mountains were a high on Turner's Late Pennsylvanian Deming Axis outlined by the Florence-Graham-Burro-Florida-West Potrillo-Moyotes-Hueco-Diablo uplifts.

Also exposed along the west base ofthe Mountain are conglomerates of pre-mid Cretaceous and Early Tertiary Laramide age indicating erosion to the Precambrian in the North Franklin Mountain area of the Southern Franklin Mountains. These rocks are cut by the north-south trending Basin and Range normal fault indicating additional uplift in Late Tertiary time. The Southern Franklin Mountains were also a high on the Early Paleozoic Transcontinetal Arch suggesting they have been a postive area throughout much of their geologic history. The displacement along the Basin and Range western boundary fault appears to be much less than the 13,000 feet estimated by previous workers.