Abstract

PALAFOX-REYES, Juan José et al. Upper Devonian and Lower Carboniferous biostratigraphy: Lower Kellwasser extinction event in Central Sonora, Mexico. Rev. Mex. Biodiv. [online]. 2022, vol.93, e934116.  Epub July 31, 2023. ISSN 2007-8706.  https://doi.org/10.22201/ib.20078706e.2022.93.4116.

Important Upper Paleozoic sequences crop out in the state of Sonora with an abundant, relatively well-preserved, fossil biota. This work aims to study the outcrops found in Cerro El Yugo, which is located in the Municipality of Arivechi, in northwestern Mexico, through high-resolution biostratigraphy based on foraminifera. Samples were prepared for thin sections and studied for microfacies analysis. Major oxides were also studied by means of X-ray fluorescence, in addition to the extraction of conodont elements by dissolving limestone with acetic acid. The study documents the biota present in the host rocks, which allows for a correlation of microfacies, major oxides and biota. Biozones of Nanicella gallowayi, Eogeinitzina devonica, Moravamminidae indet., Tikhinella measpis, Laxoendothyra parakosvensis, and Stacheoides tenuis were identified, which allowed the dating of the sequence to between the Upper Devonian (Frasnian) and the Lower-Middle Mississippian (Tournaisian-Visean). The Late Devonian (Kellwasser) event is identified in the present study by the disappearance of T. measpis and E. devonica at the Frasnian-Famennian boundary. After the Famennian, the absence of fossil biota indicates a period of recovery of it.

Keywords : Frasnian; Famennian; Foraminifera.

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