Contribution
The Pliensbachian-Toarcian boundary Ostracod Biostratigraphy in the Cordillera Iberica, northeastern Spain
Arias, Carmen
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 216 Heft 2 (2000), p. 153 - 193
94 références bibliographiques
publié: May 29, 2000
DOI: 10.1127/njgpa/216/2000/153
ArtNo. ESP155021602000, Prix: 29.00 €
Abstract
The current state of the Pliensbachian-Toarcian biostratigraphical boundary ostracod record is reviewed. A detailed description of the Pliensbachian-Toarcian boundary ostracod assemblages is given in order to determine the possibility of recognizing this boundary based on the occurrence of ostracod index taxa. The importance and the main features of the faunal turnover among ostracods during the Pliensbachian-Toarcian boundary interval is analysed. Results indicate that many species crossed the Pliensbachian-Toarcian boundary and that the main change occurred during the Tenuicostatum Zone. Also, an ostracod biozonation is proposed based on the presence of the most abundant ostracod species in the Lower Toarcian sequence of the Cordillera Iberica. Two new zones and four new sub-zones are proposed Ogmoconchella aff. Ogmoconchella aspinata and Ogmoconchella adenticulata Zone, and Kinkelinella sermoisensis Zone and Liasina lanceolata and Kinkelinella tenuicostata, Kinkelinella sp. B and Ektyphocythere dharennsourensis, Bairdiacypris dorisae and Ektyphocythere bucki, Praeschuleridea pseudokinkelinella and Ektyphocythere anterocosta subzones. The proposed zonation is correlated to the ammonite stratigraphy and has been compared with other zonal schemes proposed for the same temporal interval. As the stratigraphical ranges of many of the species used are not concordant between different areas, the correlation between the zones is problematic, and only resolved by reference to the ammonite biostratigraphical scale.
Kurzfassung
Eine kritische Durchsicht publizierter Daten und eigene Untersuchungen in der Cordillera Iberica zeigen, dass der wichtigste Wechsel in der Zusammensetzung der Ostrakodenfaunen nicht mit der Pliensbachien/Toarcien-Grenze zusammenfällt, sondern während der Tenuicostatum-Zone stattfindet. Das Untere Toarcien der Cordillera Iberica lässt sich in die Ogmoconchella aff. aspinata/Ogmoconchella adenticulata-Zone und die Kinkelinella sermoisensis-Zone unterteilen. Innerhalb der letzteren werden vier Subzonen erkannt.
Mots-clefs
Pliensbachian-Toarcian • ostracods • ammonites • biostratigraphical • biozonation • Tenuicostatum Zone • stratigraphy • Cordillera Iberica • Spain