New contributions to the Ordovician biostratigraphy of the Western Precordillera, Argentina

Abstract

Upper Ordovician graptolites and conodonts are recorded from the Yerba Loca Formation in two sections, in the El Toro and Las Viudas creeks, from the El Tigre Range in the Western Precordillera of San Juan Province, Argentina. A collection of graptolites from the late Sandbian Climacograptus bicornis Zone and conodonts on bedding plane surfaces corresponding to the Amorphognathus tvaerensis Zone are presented. Graptolites apparently corresponding to the early Sandbian Nemagraptus gracilis Zone have also been recorded. The fossils determined allow for regional and global correlations, revealing sections suitable for future integrated studies on deep marine environments that are poorly known in the Argentine Precordillera.

Keywords

• graptolites
• conodonts
• ordovician
• sandbian
• precordillera
• argentina