Earliest Permian brachiopod faunas of west-central Argentina: Defining the Pennsylvanian-Permian boundary in Gondwana

Abstract

Late Palaeozoic marine successions in the west-central Argentinian basins have one of the most complete stratigraphic records of the earliest Permian in Gondwana. Two brachiopod faunal assemblages characterize this interval: the Tivertonia jachalensis- Streptorhynchus inaequiornatus fauna, widely documented in the Río Blanco and western Paganzo basins; and the Costatumulus amosi fauna identified in the earliest Permian successions of the southern Calingasta-Uspallata Basin. This study reviews the composition and biostratigraphy of these two brachiopod faunas with special reference to their global significance for defining the Carboniferous-Permian boundary in Gondwana and deciphering the Early Permian climate change in western Gondwana.