Palynology of the Malanzan Formation (Upper Carboniferous), La Rioja Province, Argentina: New data and paleoenvironmental considerations

A new palynological association from the middle part of the Malanzan Format ion (Sierra de Los Llanos) is described. The microflora is composed of thir ty species of spores and pollen grains associated to algae, prasinophyceaes and acritarchs. The most common species of spores are Retusotriletes anfra ctus Menendez and Azcuy, Apiculiretusispora ralla (Menendez and Azcuy) Mene ndez and Azcuy, A. variornata (Menendez and Azcuy) Menendez and Azcuy, Rugo spora cortaderensis (Cesari and Limarino) nov, comb., Foveosporites hortone nsis (Playford) Azcuy, Raistrickia rotunda Azcuy, Convolutispora muriornata Menendez, Granulatisporites varigranifer Menendez and Azcuy, Cristatispori tes stellatus (Azcuy) nov, comb., C. menendezii (Menendez and Azcuy) Playfo rd, Anapiculatisporites argentinensis Azcuy, and Pustulatisporites papillos us (Knox) Potonie and Kremp. According to the known stratigraphic distribut ion of these species, a Late Carboniferous age (late Namurian-Westphalian) is proposed for the Malanzan Formation. In addition, the presence of Navifu sa variabilis nov. sp., Leiosphaeridia, Cymatiosphaera and Greinervillites suggests brackish conditions during at least part of the sedimentation of t he Malanzan Formation. Probably, this evidence suggests a postglacial trans gression (late Namurian-early Westphalian) that flooded lakes and fluvial v alleys.