Brachiopod zonation in the late Paleozoic sequences of Argentina and its correlation with other South American basins

Abstract

South America late Paleozoic brachiopod biostratigraphy is herein revised considering the recent taxonomic updates, time-sensitive fossils associated and the radiometric data available in order to provide a tentative biostratigraphic scheme. Six zones are recognized in West and East-central Argentina, namely Azurduya chavelensis (Tournaisian-early Viséan), that contains the brachiopod fauna of Michiganites scalabrinii-Azurduya chavelensis Zone, restricted to the Río Blanco Basin and also identified in northern Chile; Levipustula levis (late Serpukhovian-Bashkirian), in the Calingasta-Uspallata Basin, typically associated with the postglacial transgression of the most widespread episode in the region, and also recorded from the Bolivian Tarija Basin; Marginovatia peregrina-Maemia tenuiscostata (late Bashkirian-early Moscovian), a zone of local value defined in the Barreal Hill of the Calingasta-Uspallata basin; Tivertonia jachalensis-Streptorhynchus inaequiornatus (Moscovian-early Kasimovian?), the most widely distributed and diversified in the Precordillera, developed in relatively warm temperate conditions; and the youngest Costatumlulus amosi (late Sakmarian-early Artinskian), a low-diversity brachiopod assemblage only recorded in the southernmost part the Calingasta-Uspallata Basin; to east, in the Sauce Grande Basin, Tomiopsis harringtoni Zone (Sakmarian-Artinskian) that includes the brachiopod assemblages of the Eurydesma Fauna also identified in the Paraná Basin, Brazil (Eurydesma-Lyonia Fauna herein referred to the informal Tomiopsis-Lyonia assemblage). A posglacial brachiopod assemblage, the Aseptella-Tuberculatella/Rhipidomella-Micraphelia Fauna (late Serpukhovian-Bashkirian), relatively coeval with the Levipustula levis Zone and compositional different, is also recognized in the Calingasta-Uspallata Basin. Late Paleozoic brachiopod faunas from Patagonia associated with a late Tournaisian-Artinskian glacial sequence would not have a biostratigraphic relationship with those of west-central Argentina. A few informal brachiopod assemblages, mainly dated by fusulinids and conodonts, are herein proposed for the other South American basins. These assemblages are Tapajotia tapajotensis-Rhipidomella penniana (late Serpukhovian) in the Amazon Basin (Brazil), and also recongnized in the Moscovian of the Madre de Dios Basin (Perú); Amazonoproductus amazonensis-Anthracospirifer oliveirai (Bashkirian) in the Amazon Basin; Gypospirifer condor-Linoproductus cora (Moscovian-Sakmarian), in the Madre de Dios (Bolivia and Perú) and Navidad-Arizaro basins (Chile-Argentina), within which the species Waagenoconcha humboldti-Kochiproductus peruvianus are dominant to the Cisuralian; Alispirifer assemblage (late Bashkirian-Moscovian), in the Central Cordillera of Colombia); and the “Tethyan brachiopod assemblages” (late Pennsylvanian-Cisuralian), in the De Los Llanos Basin (Colombia and Venezuela).