PALYNOLOGY OF THE MIDDLE MIOCENE–PLIOCENE NOVO REMANSO FORMATION, CENTRAL AMAZONIA, BRAZIL

Abstract

In order to reassess and amend previously published palynological data drawn from the Novo Remanso Formation, central Amazonia, we revisited the organic-rich samples from their work using systematic and quantitative biostratigraphic analyses, with possible implications in the biodiversity and paleoecological studies of Late Neogene deposits of Amazonia. In the study area, the Novo Remanso Formation is characterized by sandstones and mudstones deposited in a meandering river environment. The palynological assemblage comprises 46 morphotypes, including 21 species of pollen and 25 species of spores. Polypodiisporites usmensis, Retitrescolpites? irregularis and Mauritiidites franciscoi var. franciscoi, typical of lowland freshwater forests and shallow water lakes dominate the assemblage. Also, lower frequencies of Grimsdalea magnaclavata co-occur with Psilatricolporites crassoexinatus, Proteacidites triangulatus, Bombacacidites simpliciriloensis, Pteridaceoisporis gemmatus and Cingulatisporites laevigatus. Based on quantitative biostratigraphic techniques, the Novo Remanso Formation is assigned a middle Miocene–Pliocene age in our study area. The presence of Elaterosporites klaszii (Albian–Cenomanian) in the Novo Remanso deposits strongly indicates Cretaceous rocks in the source-area, whereas absence of Andine palynomorphs may be indicative of a nearby source area for the deposits during the deposition of the Novo Remanso Formation.