GRAPHIC CORRELATION OF THE UPPER EIFELIAN TO LOWER FRASNIAN (MIDDLE-UPPER DEVONIAN) CONODONT SEQUENCES IN THE SPANISH CENTRAL PYRENEES

By graphic correlation of Eifelian-Frasnian sections from the Spanish Central Pyrenees, a local composite standard 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) and the Ardennes (Belgium).

Currently, the correlation project comprises three Pyrenean sections, the Compte (CP), La Guardia D’Àres (LGA) and Villech (VI), belonging to the same palaeogeographical unit, the Compte Subfacies Area of the Southern Facies Area. This set of sections, which stretches from the Upper Eifelian to the Lower Frasnian, illustrates one of the richest Givetian conodont sequences worldwide.

The CP section, yielding the most complete and detailed conodont succession for the Givetian, is selected as the Standard Reference Section for the correlation project. 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; for instance, the semialternans/latifossatus Zone is considerably thicker in the VI section than in the CP section; the Upper hermanni Zone in the LGA section is thicker than in the CP section.

This study represents an important step in the construction of the Pyrenean high resolution composite standard that, integrated into the Anti-Atlas and Ardennes composite standard, will contribute to the construction of a global Middle Devonian database and the improvement of chronostratigraphy and accuracy of intercontinental correlations for the Eifelian, Givetian and Frasnian Stages.