Resumen de Palynology of the Iscayachi Formation (Cambro-Ordovician) from the Cordillera Oriental of Southern Bolivia: new data from the western margin of Gondwana

María del Milagro Vergel, Florencio Gilberto Aceñolaza, L. Aráoz

• The first late-Cambrian aged palynomorph assemblage of Bolivia is presented. The sampled material comes from the Cambro-Ordovician Iscayachi Formation cropping out in the Antenna of the Sierra de Sama, Tarija department, southern Bolivia. The palynomorph assemblage occurs in levels correlated to the Parabolina (Neoparabolina) frequens argentina trilobite biozone. It is comprised of Acanthodiacrodium spp., Cristallinium cambriense, Cymatiogalea cf. C. aspergillum, C. velifera, C. virgulta, Dasydiacrodium spp., Eliasum llaniscum, Impluviculus multiangularis, Ladogella rommelaerei, Ladogella sp., Leiofusa sp., Leiosphaeridia sp., Lophosphaeridium sp., Lusatia? sp., Micrhystridium sp., Poikilofusa squama, Poikilofusa sp., Polygonium dentatum, Retisphaeridium brayense, Saharidia fragilis, Solisphaeridium akrochordum, S. lucidum, Timofeevia phosphoritica, Timofeevia microretis, Vulcanisphaera africana and V. turbata. The assemblage provides elements of comparison with previously reported palynofloras in northern Argentina, eastern Newfoundland, southwestern Sardinia, Algeria, northern Spain, Baltica and Avalonia (Arctic Russia, East-European Platform). All microphytoplancton are indicative of cold water affinities as expected from the western margin of Gondwana, showing some Baltic affinities as well