Open AccessNanofósseis calcários do Mioceno da Bacia do Baixo Tejo, Portugal
Author(s) -
João Paulo da Silva Lemos,
Geize Carolinne Correia Andrade Oliveira
Publication year - 2021
Publication title -
revista brasileira de paleontologia
Language(s) - English
Resource type - Journals
eISSN - 2236-1715
pISSN - 1519-7530
DOI - 10.4072/rbp.2021.1.04
Subject(s) - geology , paleoecology , biostratigraphy , calcareous , paleontology , neogene , structural basin
Calcareous nannofossils of the Lower Tejo Basin Miocene, Portugal. This study presents the taxonomy, biostratigraphy, and paleoecology of calcareous nannofossils from an outcrop on the border of Foz da Fonte beach, geologically setting in the Neogene of the Lower Tejo Basin, Portugal. The taxonomic description allowed us to identify 19 calcareous nannofossils species belonging to ten genera (Helicosphaera, Pontosphaera, Reticulofenestra, Cyclicargolithus, Coccolithus, Discoaster, Sphenolithus, Umbilicosphaera, Calcidiscus, and Thoracosphaera). Based on the stratigraphic range of Discoaster druggii, Reticulofenestra lockeri, and Helicosphaera ampliaperta the section was defined in the NN2 and CN1 biozones, within the Burdigalian (lower Miocene). Quantitative analysis showed a significant variation in species diversity as a function of depth, as well as a relationship between species richness and the calcium carbonate content present in these rocks. According to these data, mainly due to the abundance of Reticulofenestra spp., Coccolithus spp. and Helicosphaera spp., it is possible to infer that this was a nutrient-rich nearshore marine environment (eutrophic) influenced by warm water conditions. Keywords: calcareous nannofossils, taxonomy, biostratigraphy, paleoecology, Neogene, Lower Tejo Basin.