Significado Peleoecológico de Alguns Palinomorfos Ocorrentes nos Carvões Eopermianos do Rio Grande do Sul, Sul do Brasil

Abstract

Organic-walled palynomorphs of unknown botanical affinity identified in Early Permian coals from Rio Grande do Sul State, South Brazil, together with spores and pollen grains are analysed in this study. Among the identified taxa are: Tetraporina punctate, Tetraporina horologia, Maculatasporites gondwanensis, Brazilea scissa, Quadrisporites horridus, Quadrisporites lobatus, Pilasporites calculus, Portalites gondwanensis. Besides these palynomorphs, some considerations about Botryococcus braunii, a colonial alga occurring in the associations are presented. The morphological similarity between these microfossils and some algal spores spanning in age from Devonian until Recent permit significant comparisons which improve the knowledge on the spectrum of habitats of these palynomorphs. This study corroborates the idea that the peats, originated in lagoons located in coastal plains, were formed by a biomass composed of spores and pollen grains, plant cuticles, wood remains, fungi and algae, in addition to some forms related to Acritarcha or incertae sedis. Minor marine ingressions would be responsible for the occurrence, in the peat-plant association, of elements related to marine microplankton, like acritarchs, thus confirming the inference of a transitional (barrier/lagoon type) depositional environment for the coals as previously suggested by other authors.