PALAEONTOLOGY AND BIOSTRATIGRAPHY OF THE LATE PALAEOZOIC COPACABANA GROUP AT THE ANGOSTO DEL BEU, BOLIVIA

Abstract

The Copacabana Group at the Angosto del Beu, northwestern Bolivia, yielded abundant invertebrates together with fusulinids and palynornorphs that suggest an early Late Carboniferous-Early Permian age for the unit. The lower section of the group contains the fusulinid Millerella extensa Marshall, and is regarded as early Late Carboniferous in age. The upper section of the unit includes a palynological assemblage mainly dominated by taeniate disaccate pollen grains and monosaccates. The presence of Hamiapollenites insolitus (Bharadwaj and Salujha) Balme, and Pakhapites [usus (Bose and Kar) Menéndez together with several biostratigraphically useful brachiopod species such as Kochiproductus peruvianus (d'Orbigny), Neospirifer condor (d'Orbigny), and Linoproductus cora (d'Orbigny), dates the upper section of the group as Early Permian. Comparison with the lake Titikaka and the Altiplano outcrops, and the Madre de Dios subsurface sections, provides a better picture of the palaeogeograpbical evolution of the Central Andes during the Late Palaeozoic.