EIFELIAN (MIDDLE DEVONIAN) TO MIDDLE FRASNIAN (UPPER DEVONIAN) GLOBAL CORRELATION USING CONODONTS: CONTRIBUTIONS FROM THE SPANISH CENTRAL PYRENEES

The conodont record from six selected sections in the Spanish Central Pyrenees provides one of the best regional biostratigraphical data base in the world for Eifelian to Middle Frasnian rocks. This Pyrenean record allows identification and recognition of all global standard conodont zones improving the knowledge of this succession worldwide and testing its application in the Pyrenean region. This, in turn, supports the intended conodont-based subdivision of the Givetian into three substages.

The Eifelian costatus and kockelianus zones are identified by the sequential record of the respective index taxa. The ensensis Zone is inferred by its stratigraphical position between strata of the kockelianus and hemiansatus zones. Eifelian rocks are recognised in the Villech (VI), La Guardia d’Àres (LGA) and Renanué (RE) sections.

The Eifelian/Givetian boundary is defined by the entry of Polygnathus hemiansatus, which is recorded in the sections RE and LGA. All the Givetian zones are recognised by their indexes, but they are not present in each of the studied sections. The timorensis Zone is only demonstrated in RE. In other sections (LGA, VI and Compte -CP) there is a set of strata below the overlain Zone that can be attributed to the timorensis Zone.

The Lower/Middle Givetian boundary (=lower boundary of the rhenanus/varcus Zone) is identified in the RE and CP sections. The ansatus and the semialternans/latifossatus Zones are recognised in CP, RE, VI and LGA sections.

The Middle/Upper Givetian boundary (=lower boundary of the hermanni Zone) is recognised in all afore-mentioned sections. Further subdivision into Lower and Upper hermanni Zones can be reached in RE, CP and LGA. The disparilis Zone, and its further subdivision into Lower and Upper, is identified in CP, LGA and VI sections. The uppermost Givetian norrisi Zone has been identified in RE, CP, LGA and VI sections.

The Givetian/Frasnian boundary (= lower boundary of MN1 Zone) is defined by the lowest occurrence of A. rotundiloba “early” form. MN1 Zone is recorded in CP, LGA, VI and Basibé sections. In RE, is correlated by Frasnian Polygnathus. The MN2 Zone is recognised in CP, LGA and Basibé sections. In RE, is correlated by Frasnian Polygnathus and Klapperina. The MN3 Zone is present in CP and LGA sections. The MN4 and MN6 zones are only known in the Ampriú section.