Graphic correlation of the upper Eifelian to lower Frasnian (Middle-Upper Devonian) conodont sequences in the Spanish Central Pyrenees and comparison with composite standards from other areas

Résumé

Through graphic correlation of Eifelian-Givetian sections from different facies settings in the Spanish Central Pyrenees, a local composite standard based on conodonts, is established to which new data from the Pyrenees can be related. This local conodont database is compared and correlated with the Middle Devonian composite standard already containing data from the Anti-Atlas (Morocco), the Ardenne (Belgium), and the composite standard of the Montagne Noire. The correlation project comprises three Pyrenean sections (Compte, Villech and La Guàrdia d’Ares) belonging to the same paleogeographical setting tectonically located in the southern part of the European Variscan Chain. The Compte section, yielding the most complete and detailed conodont succession for the Givetian, is selected as reference for the correlation project. The combination of data from these sections permits identification, by means of the index taxa, of all Givetian standard conodont zones and subzones. The high resolution correlation and comparison of these sections shows thickness differences in several intervals. This study is an important step in the construction of the Pyrenean high resolution composite standard that, integrated into the Anti-Atlas, Montagne Noire and Ardenne composite standard, will contribute to the construction of a global Middle Devonian conodont database and the improvement of chronostratigraphy and accuracy in intercontinental correlations for the Eifelian and Givetian stages.