Triassic stratigraphy around the Sandia uplift, central New Mexico
Spencer G. Lucas and Andrew B. Heckert
Triassic strata crop out around the Sandia uplift in the Hagan basin, Placitas and Cedar Crest areas. A uniform Triassic section of nonmarine red siliciclastics as much as 480 m thick is exposed across all three areas. The base of the Triassic section is the Middle Triassic (Anisian)Anton Chico Member of the Moenkopi Formation, which disconformably overlies Permian limestones of the San Andres Formation. Moenkopi strata are as much as 20 m thick and mostly grayish red/pale–red litharenitic sandstones and siltstones. They are disconformably overlain by the Agua Zarca Formation of the Chinle Group, as much as 108 m of mostly yellowish gray sublitharenitic sandstone and extraformational conglomerate with clasts of quartzite and Paleozoic limestone. Overlying gray and purple mudstone dominated strata, as much as 92 m thick, may belong to the Salitral Formation. The uppermost Triassic strata exposed around the Sandia uplift are as much as 260 m of mostly reddish brown bentonitic mudstone assigned to the Petrified Forest Formation. A prominent, bench-forming sandstone/conglomerate unit as much as 37 m thick at the top of the Petrified Forest Formation is the Correo Member. It is disconformably overlain by the Middle Jurassic Entrada Sandstone. Few paleontological data are available from Triassic rocks around the Sandia uplift, but they can be readily correlated to nearby Triassic strata on the southern Colorado Plateau and on the southern High Plains, principally by lithostratigraphy.
- Lucas, Spencer G.; Heckert, Andrew B., 1995, Triassic stratigraphy around the Sandia uplift, central New Mexico, in: Geology of the Sante Fe Region, Bauer, Paul W.; Kues, Barry S.; Dunbar, Nelia W.; Karlstrom, K. E.; Harrison, Bruce, New Mexico Geological Society, Guidebook, 46th Field Conference, pp. 233-241.