The Bent Dome--Part of a major Paleozoic uplift in southern New Mexico
Paul W. Bauer and Richard P. Lozinsky
The Bent dome is a Proterozoic-cored structural high located in the northern Sacramento Mountains near Bent, New Mexico. The oldest rock units exposed at Bent are Proterozoic(?) altered diorite and diabase at the Virginia copper mine and altered red granite 1.6 km east. Both units are unconformably overlain by a medium-grained, well-sorted, dense quartz sandstone with abundant sedimentary structures, bioturbation and Cambro-Ordovician fish fossils that we interpret as the Bliss Sandstone. In the Virginia mine area the basal Bliss is a distinctive, bright green, glauconite-rich sandstone. In several areas the Bliss is unconformably overlain by a Quaternary red alluvial deposit that looks like Abo Formation but contains Tertiary(?) quartz-eye rhyolite clasts. The Abo Formation does unconformably overlie the Bliss Sandstone in an exposure 1.6 km east of the mine. Copper mineralization along the diorite/sandstone contact appears confined to the Virginia mine area. Prospects to the east along the contact were actually excavated in the green, glauconitic basal Bliss Sandstone. Permian rocks rest directly on Cambro-Ordovician rocks, so this area was an erosional or nondepositional high during late Paleozoic time, most likely as part of the southern prong of the ancestral Rocky Mountain Pedernal uplift. Both Cambro-Ordovician and Permian strata dip away from the core of the dome, indicating that doming continued well into Permian time.
- Bauer, Paul W.; Lozinsky, Richard P., 1991, The Bent Dome--Part of a major Paleozoic uplift in southern New Mexico, in: Geology of the Sierra Blanca, Sacramento and Capitan Ranges, New Mexico, Barker, James M.; Kues, Barry S.; Austin, George S.; Lucas, Spencer, G., New Mexico Geological Society, Guidebook, 42nd Field Conference, pp. 175-181.