132859 20260217205508.0 doi 10.1029/2023PA004738 sideral 137679 ART-2024-137679 eng Viganò, A. Calcareous Nannofossils and Paleoclimatic Evolution Across the Eocene-Oligocene Transition at IODP Site U1509, Tasman Sea, Southwest Pacific Ocean 2024 Access copy available to the general public Unrestricted The Eocene‐Oligocene transition (EOT; ∼34 Ma) was one of the most prominent global cooling events of the Cenozoic, coincident with the emergence of continental‐scale ice‐sheets on Antarctica. Calcareous nannoplankton experienced significant assemblage turnover at a time of long‐term surface ocean cooling and trophic conditions, suggesting cause‐effect relationships between Antarctic glaciation, broader climate changes, and the response of phytoplankton communities. To better evaluate the timing and nature of these relationships, we generated calcareous nannofossil and geochemical data sets (δ18O, δ13C and %CaCO3) over a ∼5 Myr stratigraphic interval recovered across the EOT from IODP Site U1509 in the Tasman Sea, South Pacific Ocean. Based on trends observed in the calcareous nannofossil assemblages, there was an overall decline of warm‐oligotrophic communities, with a shift toward taxa better adapted to cooler more eutrophic conditions. Assemblage changes indicate four distinct phases caused by temperature decrease and variations in paleocurrents: late Eocene warm‐oligotrophic phase, precursor diversity‐decrease phase, early Oligocene cold‐eutrophic phase, and a steady‐state cosmopolitan phase. The most prominent shift in the assemblages occurred during the ∼550 kyr‐long precursor diversity‐decrease phase, which has relatively high bulk δ18O and %CaCO3 values, and predates the phase of maximum glacial expansion (Earliest Oligocene Glacial Maximum–EOGM). info:eu-repo/grantAgreement/ES/MICINN-FEDER/PID2019-105537RB-I00 info:eu-repo/semantics/openAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 3.2 2024 OCEANOGRAPHY 13 / 65 = 0.2 2024 Q1 T1 PALEONTOLOGY 2 / 57 = 0.035 2024 Q1 T1 GEOSCIENCES, MULTIDISCIPLINARY 81 / 258 = 0.314 2024 Q2 T1 1.619 2024 Atmospheric Science 2024 Q1 Paleontology 2024 Q1 Oceanography 2024 Q1 6.4 2024 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Dallanave, E. Alegret, L. Universidad de Zaragoza (orcid)0000-0002-8801-9544 Westerhold, T. Sutherland, R. Dickens, G. R. Newsam, C. Agnini, C. 2000 655 Universidad de Zaragoza Dpto. Ciencias de la Tierra Área Paleontología 39, 2 (2024), e2023PA004738 [23 pp.] Paleoceanogr. paleoclimatol. Paleoceanography and Paleoclimatology 2572-4525 10242788 http://zaguan.unizar.es/record/132859/files/texto_completo.pdf Postprint 2145669 http://zaguan.unizar.es/record/132859/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:132859 articulos driver 2026-02-17-20:24:12 ARTICLE