Silurian and Devonian chitinozoan assemblages from the Chaco-Paraná basin, northeastern Argentina and central Uruguay

The Chaco-Paraná Basin is situated in northeast Argentina and central Uruguay. The basin proper can be subdivided into two sub-basins: the Alhuampa Sub-basin in the northwest, and the Rosario Sub-basin in the southeast. Samples from the Copo, Caburé and Rincón formations in the Alhuampa Sub-basin have yielded diagnostic chitinozoan species. These suggest a Ludlow-early Pridoli age for the Copo Fm., an early Pridoli age for the basal Caburé Fm., and an Eifelian sensu lato-early Givetian age for the Rincón Fm. The upper part of the Caburé Fm. probably is late Lochkovian-early Pragian, and the basal part of the Rincón Fm. can be as old as late Emsian. The evolution of the Rosario Sub-basin was seemingly different, as evidenced by strata in central Uruguay where the Cerrezuelo Fm., equivalent of the Caburé Fm., is overlain by the Early Devonian Cordobés Fm. Further investigations are required in order to confirm whether or not Lower Devonian rocks are present in the Alhuampa Sub-basin.