Palynostratigraphy and correlation of the Cisuralian Vitiacua Formation in southern Bolivia

DI PASQUO, M.M. ; GRADER, GEORGE

Corrientes

Simposio; XV Simposio Argentino de Paleobotánica y Palinología (Corrientes, 11-13 de Julio de 2012); 2012

Universidad Nacional del Nordeste

New stratigraphic and palynologic study of the Vitiacua Formation was done at La Yesera and Canaletas, near to Tarija in southern Bolivia. Eight samples yielded 62 species (11 trilete and 6 monolete spores, 11 monosaccate and bisaccate non-striate and 31 striate and costate pollen grains, and 3 algae). The Yesera Centre assemblage (YCA, one sample) is composed of Lueckisporites virkkiae (Potonié and Klaus) Klaus and several species of Vittatina, Mabuitasaccites, Striatoabieites, Corisaccites, Weylandites, and Botryococcus. The Yesera West assemblage (YWA, three samples) is characterized by monolete (Polypodiisporites mutabilis Balme, Reticuloidosporites warchianus Balme, Thymospora rugulosa Mautino et al.) and trilete spores (Lundbladispora, Convolutispora uruguaiensis Mautino et al.) and subordinate algae and pollen grains (Pteruchipollenites, Vitreisporites). The Canaletas assemblage (CA) is poorly preserved represented by pollen grains (Lueckisporites virkkiae, Striatoabieites multistriatus (Balme and Hennelly) Hart, Pteruchipollenites indarraensis (Segroves) Foster) and Botryococcus. Predominantly varied pollen grains of gymnospermous affinities occur in the YCA and CA, whereas notable pteridophytes are dominant in the YWA, being characteristic of the terrestrial landscape of the Glossopteris Flora during the Early Cisuralian in Bolivia under a temperate climate. The YCA and CA are correlated to the palynoflora from the well dated lower member of the Copacabana Formation at Apillapampa (mid Asselian-early Sakmarian), and the YWA to the overlying Coal Member (early Sakmarian- Artinskian?), known from central Bolivia and correlated to Permian units of Peru. Overall they are correlated to the middle Artinskian-Wuachiapingian Brazilian L. virkkiae Zone, the Uruguayan Striatoabieitesanaverrucosus-Staurosaccites cordubensis Zone, and the Argentinian Lueckisporites–Weylandites Zone.