Lower Ovetian (Lower Cambrian) trilobites and biostratigraphy of the Pedroche Formation (Sierra de Córdoba, southern Spain)

• Published in: Geobios 2005-05, Vol.38 (3), p.365-381
• Main Authors: Liñán, Eladio, Dies, M Eugenia, Vintaned, José Antonio Gámez, Gozalo, Rodolfo, Mayoral, Eduardo, Muñiz, Fernando
• Format: Article
• Language: English
• Subjects: Biochronologie; Biochronology; Cambrien inférieur; Earth sciences; Earth, ocean, space; Espagne; Exact sciences and technology; Invertebrate paleontology; Lower Cambrian; Ovetian; Ovétien; Paleontology; Spain; Stratigraphy; Trilobites
• ISSN: 0016-6995
• DOI: 10.1016/j.geobios.2003.11.007

The low Lower Cambrian rocks from the Sierra de Córdoba, which consist of well exposed mixed facies and abundant fossil assemblages showing long stratigraphic ranges throughout the Pedroche Formation, represent one of the best successions of this age in Europe. The fossil assemblages include diverse Ovetian archaeocyaths, trilobites, small shelly fossils, calcimicrobia, trace fossils and stromatolites. Trilobites are still poorly known, and thus they are the main objective of this work. The trilobites studied originate from three sections. At the Arroyo de Pedroche 1 section, cf. Bigotinella and Bigotina bivallata are replaced towards the top by Lemdadella linaresae, Lemdadella perejoni sp. nov. and, finally, by Eoredlichia cf. ovetensis. At the Arroyo de Pedroche 2 section, Lemdadella linaresae is replaced by Lemdadella perejoni sp. nov. and Eoredlichia cf. ovetensis, while at the Puente de Hierro section Lemdadella linaresae, L. aff. linaresae and Serrania verae occur together. These new biostratigraphic data confirm that the Pedroche Formation, originally defined as a repetitive sequence of four members, contains only two members. The new trilobite discoveries permit the first tentative correlation between the Ovetian of southern Spain and Lower Cambrian strata from the High Atlas (Morocco), Siberia, Antarctica and Carteret (France). La succession du Cambrien inférieur basal dans la Sierra de Córdoba est l'une des meilleures en Europe ; elle se compose de faciès mixtes bien exposées et d'abondants assemblages de fossiles qui montrent de longues distributions stratigraphiques dans la Formation Pedroche. Ces assemblages sont constitués d'archaeocyathes, de trilobites, de Small Shelly Fossils, de calcimicrobes, de traces fossiles et de stromatolites de l'Ovétien. Les trilobites sont encore très peu connus et sont le principal objectif de ce travail. Les trilobites étudiés proviennent de trois coupes différentes. Dans la coupe d'Arroyo de Pedroche 1, cf. Bigotinella et Bigotina bivallata sont remplacés vers le toit par Lemdadella linaresae, Lemdadella perejoni sp. nov. et, finalement, par Eoredlichia cf. ovetensis. Dans la coupe d'Arroyo de Pedroche 2, Lemdadella linaresae est remplacé par Lemdadella perejoni sp. nov. et ensuite par Eoredlichia cf. ovetensis ; dans la coupe de Puente de Hierro, Lemdadella linaresae, Lemdadella aff. linaresae et Serrania verae coexistent. Ces nouvelles données stratigraphiques confirment que la Formation Pedroche, originalem