Bioestratigrafía del silúrico (graptolitos) de la parte meridional de la zona Centroibérica Española
The biostratigraphy of the Silurian succession in a vast area of the southern Central Iberian Zone is analysed through the study of around thirty sections and isolated fossil localities, selected from over 130 sites containing Silurian graptolites. A thorough bibliographic analysis was carried out,...
| Autores: | , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Fundación Dialnet. Universidad de La Rioja |
| Repositorio: | RUIdeRA. Repositorio Institucional de la UCLM |
| OAI Identifier: | oai:ruidera.uclm.es:10578/47770 |
| Acceso en línea: | https://doi.org/10.55407/rsge.116599 https://hdl.handle.net/10578/47770 https://sociedadgeologica.org/publicaciones/revista-sge/vol-38-2-2025/ |
| Access Level: | acceso abierto |
| Palabra clave: | bioestratigrafía biostratigraphy España graptolites graptolitos Llandovery Spain Wenlock |
| Sumario: | The biostratigraphy of the Silurian succession in a vast area of the southern Central Iberian Zone is analysed through the study of around thirty sections and isolated fossil localities, selected from over 130 sites containing Silurian graptolites. A thorough bibliographic analysis was carried out, based on data from 254 studies that analyzed various aspects of the Silurian in the region. This allowed for a review of lithostratigraphic units and the refinement of their correlation within the different Variscan structures. The graptolite record is largely restricted to black shale facies associated with anoxic bottoms, between the Telychian and the early Homerian. Occasionally, rare Aeronian and Ludfordian graptolite records may also occur within dark shale intercalations recorded in units dominated by high-energy sandstones. Palaeontologically, over one hundred species of graptolites were identified, belonging to at least 32 genera, with the most biostratigraphically significant species being illustrated. Thirteen of the 15 biozones and three subzones identified range from the base of the Telychian to the early Homerian. The biozones with the greatest diversity of graptolites, as well as the widest distribution across the study area, are those of Oktavites spiralis, Torquigraptus tullbergi and Cyrtograptus perneri-Cyrtograptus ramosus. All biozones studied herein allowed an accurate correlation with the Silurian biostratigraphic succession of peri-Gondwanan regions, as exemplified by the Prague Synform, Czech Republic, with the sole exception of the global Spirograptus guerichi Biozone at the base of the Telychian. In Bohemia, this biozone features unfavourable facies for graptolites in its lower part (Rastrites linnaei Biozone). From a biostratigraphic perspective, only one biozone is identified in the Aeronian (Lituigraptus convolutus Biozone), as pre-Telychian deposits are developed in almost exclusively sandy facies. The overlying black shales contain abundant Telychian graptolite assemblages, including the biozones of Spirograptus guerichi (with its three subzones: Paradiversograptus runcinatus-Monograptus gemmatus, Parapetalolithus palmeus, and Parapetalolithus hispanicus), Spirograptus turriculatus, Streptograptus crispus, Monoclimacis griestoniensis, Torquigraptus tullbergi, Oktavites spiralis, and Cyrtograptus lapworthi. In the Sheinwoodian black shales, the Cyrtograptus murchisoni, Monograptus riccartonensis, Monograptus belophorus-Cyrtograptus rigidus, and Cyrtograptus perneri-Cyrtograptus ramosus biozones are recognised. Finally, the Homerian and Ludfordian strata are represented by the Cyrtograptus lundgreni and Saetograptus leintwardinensis (?) biozones, which correspond respectively to the end of black sapropelitic deposition (diachronous in the study area), and to a local intercalation of this lithology within the sandy alternations in the upper part of the succession. |
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