Berriasian–early Valanginian calcareous shallow-water facies from the Arperos Basin: A proposal from the foraminiferal assemblage of the clasts of the Guanajuato Conglomerate, central Mexico

• Published in: Boletín de la Sociedad Geológica Mexicana 2015-01, Vol.67 (1), p.45-57
• Main Authors: Omaña, Lourdes, Miranda-Avilés, Raúl, Puy-Alquiza, María Jesús
• Format: Article
• Language: English
• Subjects: ARTÍCULOS REGULARES / REGULAR ARTICLES; Biostratigraphy; Carbonates; Conglomerates; Geological facies; Geology; Geosciences, Multidisciplinary; Limestones; Microfossils; Micropaleontology; Turkeys; Valanginian age
• ISSN: 1405-3322; 1405-3322
• DOI: 10.18268/bsgm2015v67n1a4

The Eocene Guanajuato Conglomerate is composed of clasts derived from igneous and metasedimentary sources that can be related to the Upper Jurassic-Lower Cretaceous arc and back-arc assemblages of the El Paxtle and Arperos Basin. Limestone clasts contain a shallow-water platform fauna that includes bivalves, brachiopods, gastropods, echinoderms and foraminifers. Foraminiferal studies were carried out on these limestone clasts. The benthic foraminiferal association is composed ofPseudocyclammina lituus(Yokoyama, 1890);Everticyclammina virguliana(Koechlin, 1942);Montsalevia salevensis(Charollais, Brönnimann and Zaninetti, 1987);Neotrocholina valdensis(Reichel, 1955);Andersolina cherchiae(Arnaud-Vanneau, Boisseau and Darsac, 1988);Neotrocholina molesta(Gorbatchik, 1959);Pfenderina neocomiensis(Pfender, 1938);Nautiloculina bronnimanniArnaud-Vanneau and Peybernès, 1978;Hechtina praeantiquaBartenstein and Brand, 1949;Protopeneropliscf.P. banaticaBucur, 1993;Istriloculinasp.,Moesiloculinasp.,Protomarsonellasp.,Ammovertellinasp. andGlomospirasp. The Tethysian foraminiferal assemblage observed in the limestone clasts indicate the age of the calcareous source as Berriasian–early Valanginian, which is the age of the deposition within the Arperos Basin. The occurrence of these shallow-water limestone clasts suggests the existence of a shallow-water platform deposit located in the Arperos Basin. This is significant considering that all previous work focused on the deep-water sedimentary rocks (siliciclastic and calcareous). Thus, these clasts are a key to reconstructing the depositional history and architecture of this basin.