Disconformity between the El Abra Formation underlying the “Temazcal unit” in Cerro Quemado locality, Temazcal, San Luis Potosí, Mexico: Biostratigraphy and microfacies analysis

Disconformidad entre la Formación El Abra, subyaciendo la “unidad Temazcal” en la localidad Cerro Quemado, Temazcal, San Luis Potosí, México: bioestratigrafía y análisis de microfacies

Lourdes Omaña ^1,*, Rubén Alfonso López Doncel ², José Ramón Torres Hernández ², José Rafael Barboza Gudiño ²

¹ Departamento de Paleontología, Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, CDMX, Mexico.

² Instituto de Geología, Universidad Autónoma de San Luis Potosí, Av. Dr. Nava # 5, San Luis Potosí, Mexico.

* Corresponding author: (L. Omaña) This email address is being protected from spambots. You need JavaScript enabled to view it.

How to cite this article:

Omaña, L., López Doncel, R.A., Torres Hernández, J.R., Barboza Gudiño, J.R., 2022, Disconformity between the El Abra Formation underlying the “Temazcal unit” in Cerro Quemado locality, Temazcal, San Luis Potosí, Mexico: Biostratigraphy and microfacies analysis: Boletín de la Sociedad Geológica Mexicana, 74 (1), A250821. http://dx.doi.org/10.18268/BSGM2022v74n1a250821

ABSTRACT

On the western part of the Valles–San Luis Potosí Platform located in Cerro Quemado near Temazcal, municipality of Armadillo de Los Infante, two sequences crop out. The lower one is the shallow-water El Abra Formation of the mid–upper Cenomanian, unconformably covered by a deep-water deposit of the upper Maastrichtian informally called here the “Temazcal unit.” The succession presents a nonconforming contact between these two sedimentary units, displaying a hiatus as the result of a time of non-deposition in the sedimentary record, showing a subaerial exposure with erosion yielding topographic relief. Based on the lithological changes from the underlying limestone toward the overlying silty limestone, as well as a detailed biostratigraphic study based on foraminiferal associations that provide an accurate dating, it has been possible to estimate the magnitude of the hiatus, which spans from the lower part of the Turonian, including the Coniacian, the Santonian, and possibly the lower part of the Maastrichtian.

Keywords: Disconformity, El Abra Formation, “Temazcal unit”, San Luis Potosí, Mexico.