CONICET | Buscador de Institutos y Recursos Humanos

New detailed stratigraphic and paleontologic study of upper Devonian rocks and lower Permian strata was carried out at Apillapampa, in central Bolivia. New palynological results from dark shales in the marine Tequeje and Copacabana formations provide new information to help refine ages and correlation of these units. Two samples from the Tequeje Formation 80 and 18 m below an erosional, very low angle unconformity with basal Copacabana sandstones yielded abundant and well preserved specimens of the chitinozoans (e.g., Urochitina loboi, Cingulochitina serrata, C. ervensis, Angochitina strigosa, A. filosa, Pterochitina megavelata), acritarchs (e.g., Pulvinosphaeridium trifidum) and spores allowing the recognition of the Late Lochkovian U. loboi Zone Grahn. The first Copacabana sample 10 m above the contact with basal sandstones (the Yaurichambi Fm.) yielded few species of Vittatina characteristic of the Asselian-early Sakmarian Vittatina costabilis Zone Souza and Marques Toigo. The appearance of Lueckisporites nyakapandensis at 69 m and L. virkkiae at 143 m gives correlation to the middle Artinskian-Wuachiapingian L. virkkiae Zone of the Paraná Basin. Some species present in the lower Copacabana also occur in the overlying Coal Member (6 samples), however these samples also yielded abundant monolete (e.g., Polypodiisporites mutabilis, Thymospora rugulosa) and trilete spores (Lundbladispora braziliensis, L. riobonitensis, Lycospora variabila, Convolutispora uruguaiensis) with subordinate non-striate monosaccate and bisaccate (Pteruchipollenites, Alisporites) and striate pollen grains. The Permian ages of the Paraná Basin are currently constrained with radiometric data similar to correlative zones in Argentina, Uruguay, Africa and Arabia. Comparison to conodont, fusulinid, and ash ages is in preparation.

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