Geology of the Ima NW Quadrangle, east-central New Mexico
— Spencer G. Lucas, Gary Weadock, Kenneth K. Kietzke, Adrian P. Hunt, and Barry S. Kues
The Ima NW quadrangle, located along part of the eastern border of Guadalupe County with Quay County, straddles the edge of the Southern High Plains (Llano Estacado) and the drainage divide between the Canadian and Pecos Rivers. No substantial geologic structures are exposed on the quadrangle, which is underlain by an essentially flat-lying section of Upper Triassic, Middle-Upper Jurassic, Lower Cretaceous and Neogene sedimentary rocks –330 m thick. About half of that section (-170 m) is Upper Triassic nonmarine red beds of the Trujillo, Bull Canyon and Redonda formations of the Chinle Group. A much thinner (-63 m thick) section of overlying Jurassic strata belongs to the Entrada (Slick Rock and Exeter members), Todilto (Luciano Mesa Member), Summerville and Morrison formations. The Lower Cretaceous section is also thin (-30 m) and assigned to the upper Albian Tucumcari and Mesa Rica formations. Fossils from the Bull Canyon, Todilto, Tucumcari and Mesa Rica formations on the Ima NW quadrangle are abundant and of biostratigraphic significance. Neogene strata on the quadrangle belong to the Ogallala Formation, which underlies the Llano Estacado, and alluvial, eolian and colluvial units of Pleistocene age that are mostly exposed along Bull Canyon and Alamogordo Creeks.
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- Lucas, Spencer G.; Weadock, Gary; Kietzke, Kenneth K.; Hunt, Adrian P.; Kues, Barry S., 2001, Geology of the Ima NW Quadrangle, east-central New Mexico, in: Geology of the Llano Estacado, Lucas, Spencer G.; Ulmer-Scholle, Dana S., New Mexico Geological Society, Guidebook, 52nd Field Conference, pp. 191-201.