Cretaceous stratigraphy and biostratigraphy in the southern San Andres Mountains, Dona Ana County, New Mexico
Spencer G. Lucas and John W. Estep
Cretaceous strata exposed in the southern San Andres Mountains belong to the Sarten, Dakota, Mancos, Tres Hermanos, and Gallup Formations. The Sarten Formation is as much as 12.3 m thick and mostly consists of very fine, silty hematitic sandstone. A poorly preserved Late Albian fossil assemblage from the Sarten Formation is dominated by specimens of the bivalves Texigryphaea washitaensis, Protocardia texana, and Neithea texana. The Dakota Sandstone is as much as 50 m thick and consists mostly of trough-crossbedded quartzarenitic sandstone. The 13-m-thick Rio Salado Tongue of the Mancos Shale above the Dakota contains a thin nodular limestone interval 4.5 m above its base correlated to the Bridge Creek Member of the Greenhorn Limestone. The Rio Salado strata produce inoceramids and ammonoids that indicate they belong to the Mammites nodosoides Zone of late Early Turonian age. The Atarque Sandstone is 14 m thick, mostly fine-grained sandstones and produces a bivalve assemblage dominated by Lopha bellaplicata. The overlying 11 m of marine(?) shale are assigned to the D-Cross Tongue of the Mancos Shale. The preserved Cretaceous section in the southern San Andres Mountains is capped by about 27 m of sandstone assigned to the Gallup Sandstone.
- Lucas, Spencer G.; Estep, John W., 1998, Cretaceous stratigraphy and biostratigraphy in the southern San Andres Mountains, Dona Ana County, 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. 187-196.