Bioestratigrafía de conodontos del Darriwiliense medio (Ordovícico) en el borde oriental de la Sierra de Villicum (Precordillera Oriental, Argentina)

摘要: A transitional contact between the San Juan and Los Azules formations is present in eastern flank of Villicum Range. The very top characterized by dark greenish grey to black burrowed bioclastic wackestone tabular packstone-grainstone. Formation composed shale with levels nodules mudstone. detailed study conodont fauna biostratigraphy uppermost metre lower formation from three sections suggesting Yangtzeplacognathus crassus Zone for these levels. correlation studied Eastern Precordillera those Central allows us suggest that Las Aguaditas was diachronic during Darriwilian, Y. Eoplacognaths pseudoplanus zones, we conclude younger tops are found western-central part Precordillera.