2025-01-092025-01-092023-12-21FURTADO, Bianca da Silva. Ostracodes da Formação Pirabas (Oligo-Mioceno), Plataforma Bragantina, município de Vigia, nordeste do estado do Pará, Brasil. Orientadora: Anna Andressa Evangelista Nogueira. 2023. 75 f. Trabalho de Conclusão de Curso (Bacharelado em Geologia) - Faculdade de Geologia, Instituto de Geociências, Universidade Federal do Pará, Belém, 2023. Disponível em:https://bdm.ufpa.br/jspui/handle/prefix/7590. Acesso em:.https://bdm.ufpa.br/jspui/handle/prefix/7590This study helps the understanding of the presence of neogene deposits provenient from the Bragantina Platform’s westernmost portion, although it still presents disagreements from previous studies about the limits, primarily, between this platform and Marajó Basin. Thirty samples were obtained and analyzed from borehole P12 Vigia - VN, from the Vigia County, near the Vigia-Castanhal Trough, in the state of Pará. Between these samples, 74 ostracode species were identified for paleoenvironmental, biostratigraphic studies with eyes to aknowledge the occurrence of Bragantina Platform in its westmost site, at the limits with the Vigia-Castanhal Trough. According to the multivariate analyses (Cluster and SIMPER), it was possible to establish three biofacies, for which the following paleoenvironments were interpreted: transitional environment (B1), lagoon (B2) and nearshore marine platform (B3). Diversity indices analysis showed greater diversity and abundance in the lower intervals of the studied section, at the biofacies B3, with a gradual reduction towards the top of the sequence, where biofacies B1 and B2 occur. This is also reflected in the values of Simpson, species abundance or Taxa (S), Shannon (H’), Alpha-Fisher (α) and equitability (J) indices, where their maximum values indicate neritic conditions (depth intervals from 142 meters to 162 meters, towards the bottom of the section) and minimum values indicate brackish conditions from transitional and lagoon environments (100 meters to 140 meters depth). Previous studies related to the observed genera paleoenvironments, together with the lithologies within the profile, allowed to infer an increasingly clastic influence on the sedimentary input from the base to the top of the sequence. The previously stablished biozonation from other localities of the Pirabas Formation revealed in this research one biozone and two sub-biozones, regional and global, along the section: 1 – the Cytherella stainforthi biozone (Neo-Oligocene-Eomiocene); 2 – the Quadracythere brachypygaia sub-biozone (Neo-Oligocene) and; 3 – the Neocaudites macertus sub-biozone (Eomiocene). These results allowed a better comprehension of westernmost limits extension between Bragantina Platform and the Vigia-Castanhal Trough, and the identified ostracode species will expand the knowledge related to these microfossils zonation in the region, extending further the occurrence of the Pirabas Formation associated deposits at the western portion of the Bragantina Platform, in addition to the better positioning of this platform and its bordering units to the west.Acesso AbertoOstracodesFormação PirabasFossa Vigia-CastanhalOstracodsPirabas FormationVigia-Castanhal TroughCNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIATrabalho de Curso - Graduação - Monografia