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-The aim of this paper was to assess, in a study case, whether ash-fall deposition influenced the character of the peat-forming vegetation in some coal beds in the southernmost Paraná Basin in Brazil, taking into consideration that records of tonstein levels are common in some coal bearing-strata. An investigation was made of the uppermost Faxinal coal seam (Coal Seam S), which displays two adjacent coal beds interbedded with a tonstein level. On the basis of the botanical affinity between the miospores and the parent plants as well as the relative abundance of the different plant groups, each coal plant assemblage was determined. Furthermore, previous paleobotanical data obtained on the tonstein level that identified a compressed Glossopteris flora were incorporated in the study. Palynofacies analyses performed on both coal and tonstein levels demonstrated good results for the recognition of preserved organic matter and changes in paleoenvironmental conditions along the coal sequence. The effect of volcanic ash-fall deposition was reflected by changes in the character of the vegetation associated with coal layers below and above the tonstein. Palynofacies results corroborated palynological and paleobotanical interpretation and contributed to the establishment of the floral succession deposited over a short time interval, under the effect of volcanic ash-fall deposition.Key words: palynology, paleobotany, palynofacies, coal, tonstein, Paraná Basin.RESUMO -O trabalho objetivou avaliar o efeito da deposição de cinza vulcânica sobre o caráter da vegetação responsável pela formação de alguns carvões na jazida do Faxinal, levando em consideração que registros de tonstein são comuns em sequências de carvão na porção sul da bacia do Paraná, no Brasil. Em estudo de caso, foi analisada a camada de carvão superior (Camada S) que apresenta, na sua porção mais superior, dois leitos adjacentes de carvão intercalados por um nível de tonstein originado de cinza vulcânica. A composição das palinofloras foi determinada com base na afinidade dos esporos e dos grãos de pólen e na relação de freqüência dos diferentes grupos vegetais. Dados paleobotânicos anteriores desenvolvidos nesse nível de tonstein, que demonstraram a presença de uma importante Flora Glossopteris, foram incorporados ao trabalho aqui proposto. As análises de palinofácies produziram resultados significativos para o reconhecimento da matéria

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