A new trilobite locality from the Agüeira Formation (Upper Ordovician) of the Vega de Espinareda synclinorium (West Asturian-Leonese Zone, NW Spain) and its stratigraphical interest
DOI:
https://doi.org/10.55407/geogaceta100693Keywords:
Ordovician, Iberian Massif, Agüeira Formation, biostratigraphy, West Asturian-Leonese zoneAbstract
A new paleontological locality in the Ordovician of northwestern Spain is presented, situated north of Ponferrada (León province), on the southern flank of the Vega de Espinareda synclinorium. This is the eighth locality with skeletal fossils found in the Agüeira Formation (Upper Ordovician) of the Navia Alto Sil Domain of the West Asturian-Leonese Zone, and the first recorded in the lower half of the Formation. The new locality is very close to its reference section in the fluvial gorge between the towns of Congosto and Santa Marina del Sil, where these lower beds were interpreted as distal facies of a submarine turbiditic fan, adjacent to the basinal plain. However, the trilobites, brachiopods and mollusks here studied, which do not seem to have been transported due to their little to no disarticulation, reveal an assemblage typical of much shallower shelf environments, with oxigenated seafloor as demonstrated by the abundance of horizontal burrows. The record of the trilobites Colpocoryphe grandis (Šnajdr) and Dalmanitina n. sp. (D. rabanoae Pereira, n. n.) indicates an early Berounian (=early Sandbian) age, which opens the possibility that the Middle/Upper Ordovician boundary could be placed in the studied area within the lower 400-500 m of the Agüeira Formation.
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Copyright (c) 2024 Sara Romero, Sofia Pereira, Ramiro López Medrano, Francisco Arias Ferrero, Isabel Rábano, Jorge Colmenar, Juan Carlos Gutiérrez-Marco
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