Miocene paleoenvironmental changes in the Solimões Basin, western Amazon, Brazil: A reconstruction based on palynofacies analysis
Abstract We report palynofacies from two sections of Miocene Solimoes Formation of the Solimoes Basin, western Amazon, Brazil to better understand paleoenvironmental evolution. Based on cluster analysis, five palynofacies associations were recognized, dominated by either opaque, non-opaque, algae, miospores and structureless/marine organic matter. The distribution of palynofacies associations reflects a complex depositional system with fluvial, lacustrine, estuarine, and shallow marine environments. A high abundance of woody material indicates a fluvial-lacustrine-dominated environment. Three marine incursions were recognized, indicated by the presence of dinoflagellate cysts and microforaminifera test linings. Marine influence was more evident during the late Middle-Late Miocene interval, when transgressions occurred over a greater extent of the Amazon region.