CONICET | Buscador de Institutos y Recursos Humanos

Newly biostratigraphic research conducted in the Huaytiquina section (Salta province), allowed to obtain the first record of Middle Ordovicianconodonts for the western Argentine Puna. The analyzed material comes from calcareous sandstones levels intercalated in the lower portionof the turbiditic succession corresponding to the Coquena Formation. The recovered conodont fauna is composed by species of thegenera Baltoniodus, Gothodus, Trapezognathus, Drepanoistodus, Drepanodus, few elements of Microzarkodina andProtopanderodus, among others. Although the conodont elements are very abundant, the diversity is very low, being the Gothodus elementsthe most numerous in each sample. The conodont associations indicate a Dapingian (Middle Ordovician) age, linking the conodonts ofthe Argentine Puna with those from Baltoscandinavia. The productive levels also contain graptolites of the Tetragraptus genus, andare closely related to strata bearing Azygograptus lapworthi Nicholson and Xiphograptus lofuensis Lee which are confirming theDapingian age of the lower and middle portions of the Coquena Fm. The occurrence of Azygograptus lapworthi was also recently recordedin the Argentine Cordillera Oriental related to the index conodont Baltoniodus triangularis Lindström. The new findings, suggest that a highresolutioncorrelation between both geomorphological regions could be possible, and they also certify that both sectors of the Central AndeanBasin were connecting during the interval corresponding from the Lower Ordovician (Floian) to the Middle Ordovician (Dapingian).Future taxonomic studies of larger conodont collections and graptolites key taxa will make it possible to accurate the age of the CoquenaFm., improving its regional and global correlations.