Palynostratigraphy and sedimentary facies of Middle Miocene fluvial deposits of the Amazonas Basin, Brazil

摘要: Abstract Palynostratigraphic and sedimentary facies analyses were made on deposits from the left bank of Solimoes River, southwest Manaus, State Amazonas, Brazil. These provided age-dating subdivision a post-Cretaceous stratigraphic succession in Amazonas Basin. The Novo Remanso Formation is subdivided into upper lower units, delineated by discontinuous surfaces at its top bottom. formation consists primarily sandstones minor mudstones conglomerates, reflecting fluvial channel, point bar floodplain meandering paleosystem. Fairly well-preserved palynoflora was recovered four palynologically productive samples collected local irregular concentration gray clay deposits, rich organic material fossilized wood, unit. dominated terrestrial spores pollen grains, characterized abundant angiosperm grains ( Tricolpites , Grimsdalea Perisyncolporites Tricolporites Malvacearumpollis ). Trilete are almost as pollen, represented mainly genera Deltoidospora Verrutriletes Hamulatisporis . Gymnosperm scarce. presence index species magnaclavata Germeraad et al. (1968) indicates that these belong to Middle Miocene homonymous palynozone (Lorente, 1986; Hoorn, 1993; Jaramillo et al., 2011). Sedimentological characteristics (poorly sorted, angular sub-angular, fine very-coarse quartz sands facies) typical part. associated with paleoflow NE-E SE-E, an entirely lowland-derived palinofloristic content no Andean ferns gymnosperms representatives. All together, this suggests cratonic origin for paleosystem, which probably born Purus Arch eastern flank areas surrounding crystalline. palynological analysis results presented herein first direct unequivocal evidence occurrence central part They also provide new perspectives intra- interbasin correlations, well paleogeographic paleoenvironmental interpretations later deposition stages northern Brazilian basins.