Age correlations for the acoite formation (lower ordovician) at Aguas Blancas Creek in the Cordillera Oriental of Jujuy province, Argentina

Abstract

Here, we use conodont and graptolite assemblages to age correlate the ‘Sepulturas limestones’ facies of the Acoite Formation exposed at Aguas Blancas Creek, near Altos de Lip an in the Cordillera Oriental of Jujuy Province, Argentina. An association of autochthonous conodont species is identified consisting of Drepanodus arcuatus, Drepanoistodus pitjanti, Erraticodon patu, Gothodus andinus, Paroistodus parallelus and Zentagnathus argentinensis. Tubaria referable to the graptolite genera Acrograptus, Baltograptus and Tetragraptus are also present. This assemblage corresponds to the middle interval of the Gothodus andinus Zone, together with the upper Tetragraptus azkharensis Zone, or possibly the lower Baltograptus cf. B. deflexus Zone, which collectively indicate an early to middle Floian (Early Ordovician) age. Lithological and faunal characteristics of the studied succession imply deposition in a shallow marine environment. We also suggest that the Aguas Blancas section is stratigraphically younger than the other upper outcrops exposed around the town of La Cienaga, where the ‘Sepulturas limestones’ were originally defined.