UPPER DEVONIAN CONODONTS FROM THE PI SECTION IN THE SERRA DEL CADÍ, SPANISH PYRENEES

The Devonian/Carboniferous (D/C) boundary Global Boundary Stratotype Section and Point (GSSP) at La Serre, France, was defined by the appearance of an uninterrupted record of Siphonodella praesulcata to S. sulcata. Since then, numerous issues have been made clear, including that the stratotype section was determined to be imprecise due to reworking of the bed and the discovery of an earlier first occurrence of S. sulcata. A new boundary definition and locality for a stratotype section are being investigated.

The Pi section along Torrent de Pi south of the village of Pi, Lleida, has a thickness of 60 m and consists of variegated hemipelagic limestone deposited on a carbonate platform assigned to the uppermost part of the Comabella, La Mena, and Barousse formations. These strata were previously mapped and collected by Valenzuela-Ríos with the Geographical and Geological Survey of Catalonia in 2001 and was re-measured and analyzed for conodonts. This study documents two recollected horizons (Pi-1, Pi-2c) and two additional lower horizons (Pi-2b, Pi-2a) in the upper part of the section. The conodonts in the upper Pi section consist of a diverse fauna of relatively long ranging taxa typical of an offshore facies, dominated by Bispathodus, Branmehla, Palmatolepis, Polygnathus, and Pseudopolygnathus. The oldest sample, Pi-2a, indicates the Bispathodus ac. aculeatus Zone based on the first occurrence of Bi. ac. aculeatus. The youngest sample, Pi-1, is in the Bispathodus ultimus Zone based on the occurrence of Polygnathus purus purus in association with typical Upper Devonian taxa. The absence of protognathoidids, including the base of Carboniferous defining Protognathodus kockeli, and no distinct Hangenberg event strata do not allow recognition of the D/C boundary.