Resumen

EGUILUZ Y DE ANTUNANO, Samuel  y  LOPEZ-MARTINEZ, Rafael. Calpionellids in a volcano-sedimentary succession in Guanaceví, Durango, western Mexico. Bol. Soc. Geol. Mex [online]. 2024, vol.76, n.1, A300124.  Epub 07-Oct-2025. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2024v76n1a300124.

In Guanaceví, Durango, previous works describe a volcano-sedimentary succession referred to as the Lower Volcanic Complex. In this succession, Calpionella alpina, Calpionella elliptica and Tintinnopsella carpathica were reported in limestone strata considered to be from the Middle Berriasian. The locality of this find is imprecise, and no taxonomic evidence of the microfossils was provided to verify their presence in rocks of this age in western Mexico. The objective of this work is to offer taxonomic evidence of the fossiliferous assemblage composed of Chitinoidella sp., Crassicollaria sp., Crassicollaria massutinianna, Remaniella sp., and Tintinnopsella carp a thica, from the late Tithonian to the early Berriasian, likewise, the precise location of the fossiliferous localities is given. The presence of the fossiliferous assemblage treated here, together with previous reports on the relatively close existence of Crassicollaria massutinianna, extends the distribution of calpionellids, from a Tethyan environment to the Boreal Pacific realm in western Mexico.

The stratigraphic succession in which the fossils are found is formed, at the base, by polymictic and immature conglomerate, which gradually passes into sandstone, shale, and limestone, with tuff and andesite spills interspersed. The characteristics of these lithologies possibly represent a transgression, from continental facies to marginal coastal and deep marine facies, with volcanism.

Palabras llave : Chitinoidella; Crassicollaria; Remaniella; Tintinnopsella carpathica; transgresión; Tithonian-Berriasiano; Pacific realm.

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