Jurassic stratigraphy of the southeastern Colorado Plateau, west-central New Mexico: 2020 synthesis
— Spencer G. Lucas


Jurassic strata exposed on the southeastern Colorado Plateau in west-central New Mexico encompass part of the southern edge of the Jurassic outcrop belt in the Western Interior. The water-deposited Jurassic stratigraphic units pinch out or are truncated southward in west-central New Mexico, so that in the southernmost reaches of the Jurassic outcrop belt the entire Jurassic section is merged eolian sandstones. These merged eolian sandstones are assigned to the Zuni Sandstone, and to the north and northeast the Jurassic section is assigned to (in ascending order) the Entrada Sandstone (Dewey Bridge and Slick Rock members), the Todilto Formation (Luciano Mesa and Tonque Arroyo members), the Summerville Formation, the Bluff Formation (main body and Recapture Member), the Acoma Tongue of the Zuni Sandstone (all in the San Rafael Group) and the Morrison Formation (Salt Wash, Brushy Basin and Jackpile members). The ages of Jurassic lithostratigraphic units in west-central New Mexico range from Callovian to Tithonian based on regional stratigraphic relationships and on radioisotopic ages and biostratigraphic data, mostly from Utah and Colorado. The lithostratigraphy advocated for Jurassic strata in west-central New Mexico provides the basis for a Jurassic sequence stratigraphy in west-central New Mexico that recognizes four regional unconformities: J-2 (base of the Entrada and Zuni sandstones), J-3 (base of the Todilto Formation), J-5 (base of the Salt Wash Member of the Morrison Formation) and K-0 (base of the Cretaceous Dakota Formation).

Full-text (971 KB PDF)

Recommended Citation:

  1. Lucas, Spencer G., 2021, Jurassic stratigraphy of the southeastern Colorado Plateau, west-central New Mexico: 2020 synthesis, in: New Mexico Geological Society, 71st Annual Fall Field Conference, September 2021, Geology of Mount Taylor, Frey, Bonnie A.; Kelley, Shari A.; Zeigler, Kate E.; McLemore, Virginia T.; Goff, Fraser; Ulmer-Scholle, Dana S., New Mexico Geological Society, Guidebook, pp. 241-250. https://doi.org/10.56577/FFC-71.241

[see guidebook]