Silurian Acritarchs from the Trombetas Formation, Amazon Basin - Brazil

Abstract

Analysis of a sample from the Viramundo falis, lower part of the Pitinga Member, Trombetas Formation, reveals a diversified and well-preserved palynoflora. Twenty-three species of acritarchs are identified, including several guide-fossils, indicative of a biostratigraphic interval corresponding to the Ludlovian. This assignrnent reinforces recent conclusions by other authors, supporting the idea of a gradational contact between the Trombetas Formation and the overlying Maecuru Formation. The assemblage was certainly deposited in a neritic marine environrnent, probably under low salinity conditions.