Palynostratigraphy of the Lower Cretaceous Rio Mayer Formation in the Rio Lista area, Austral Basin, southwestern Argentina

Palynomorph assemblages were recovered from the upper levels of the Cretaceous Rio Mayer Formation in the Rio Lista area, Austral Basin, southern Argentina. Thirty spore and eighteen pollen species, including one angiosperm, are identified, along with fourteen dinoflagellate cysts and six acritarch taxa. The presence of Clavatipollenites spp. and the dinoflagellate cysts Muderongia mcwhaei, Diconodinium spp., and Muderongia australis suggest an early Aptian age for these palynological assemblages. Based on the relative abundance of the major groups of palynomorphs, deposition of the Rio Mayer Formation in the Rio Lista area probably occurred in a progressively shallowing marine setting, evidenced by the decrease in abundance of marine elements (dinoflagellates) and the increase of Pterospermella in upper levels of the unit. These interpretations concur with sedimentological analyses of the same stratigraphic section. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Palynomorph assemblages recovered from the upper levels of the Cretaceous Rio Mayer Formation in the Rio Lista area, southern Argentina, suggest an early Aptian age and a progressively shallowing marine setting for deposition of the unit, as evidenced by the decrease in abundance of marine elements and the increase of Pterospermella. These interpretations are consistent with sedimentological analyses of the same stratigraphic section.