Taxonomy, biostratigraphy and biofacies of an Upper Ordovician (Katian) conodont fauna from the Casaio Formation, Northwest Spain

VOLDMAN, G.G.; TOYOS, J.M.

BULLETIN OF GEOSCIENCES

CZECH GEOLOGICAL SURVEY

Lugar: Praga; Año: 2019 vol. 94 p. 455 - 478

1214-1119

Although Katian conodont faunas from high-latitude to peri-Gondwanan regions are widelyreferred to in the literature, their taxonomy is not yet stabilised, which iscritical to biostratigraphically constrain the climate and tectonic events precedingthe Hirnantian mass-extinction. In the present contribution, 595 conodontelements and abundant fragmentary conodont material recovered frommeta-limestones of the Casaio Formation, northern Central Iberian Zone, istaxonomically and biostratigraphically analysed. The conodont assemblage ischaracterised by the genera Amorphognathus,?Baltoniodus, ?Drepanoistodus, ?Drepanodus?,Eocarniodus, Hamarodus, Icriodella, Istorinus, Panderodus, Sagittodontina,Scabbardella, and Walliserodus, and documents the lower Amorphognathus ordovicicus Zone (Ka3) inNorthwest Spain. After the taxonomic analysis, Icriodella iberiensis sp. nov. is proposed, and the complexity ofthe balognathid genera Sagittodontina and Amorphognathus is further discussed. Based on the composition of the majorcomponents, a new Icriodella?Sagittodontina?Amorphognathus Biofacies is introduced. Conodont based correlations and cluster analysisverify the strong similarity of the conodont assemblage of the Casaio Formationwith the Thuringian conodont faunas from the Upper Ordovician MediterraneanProvince.