A Pleistocene (MIS 5e) mollusk assemblage from Ezeiza (Buenos Aires Province,Argentina) |
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| Institution: | 1. Institute of Molecular Genetics of Russian Academy of Sciences, Kurtchatov Sq. 2, Moscow 123182, Russia;2. Federal State-Financed Educational Institution of Higher Professional Education, Moscow State Pedagogical University, M. Pirogovskaya Str. 1/1, Moscow 119991, Russia;1. LARAMG – Laboratório de Radioecologia e Mudanças Globais/DBB/IBRAG/Universidade do Estado do Rio de Janeiro, Pavilhão Haroldo L. Cunha, Subsolo, Rua São Francisco Xavier, 524, Maracanã, Rio de Janeiro, RJ, 20550-013, Brazil;2. Departamento de Geoquimica, Universidade Federal Fluminense, Departamento de Geoquímica/IQ, Morro de Valongunho S/n, 5 Andar, Centro, Niterói – RJ, 21020-007, Brazil;3. IRD-LOCEAN (UMR 7159 IRD/CNRS/UPMC/MNHN)—Institut Pierre-Simon Laplace, Bondy, France;4. Centro Regional Sul de Pesquisas Espaciais/INPE Campus Universitário – UFSM, Caixa Postal no. 5021, Santa Maria, RS, 97105–970, Brazil;5. School of Arts, Sciences and Humanities, University of São Paulo, São Paulo, Brazil;6. Av. Arlindo Bettio, 1000, CEP03828-000, São Paulo SP, Brazil |
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| Abstract: | A fossil assemblage collected around 3.5 m amsl from Ezeiza, Buenos Aires province, have AMS 14C ages of ca. 33,000 to ca. 40,000 yr BP, whereas in the literature is a report of a conventional 14C age of >43,000 yr BP. An OSL age from the overlying deposit corresponds to ca. 22,000 yr. The samples contain marine fossils: mollusks, balanids and corals (Astrangia). La Coronilla (Uruguay, attributed to MIS 5e) is the locality most related to Ezeiza faunistically, despite is not the nearest one. In consequence, the relationship should be addressed to a more similar age and environment than others. The fauna indicates a higher water temperature than today. In Ezeiza exclusively cold water taxa are absent, and we found seven warm taxa with their southern distribution limit displaced northwards today, plus other six at their southern distribution limit. Around 60% of all the species and more than 70% of the individuals are of warm-temperate waters. In sum, although prima facie the numerical ages would locate the deposit in MIS3, faunistic, temperature, and height evidences show that the Ezeiza mollusk assemblage belong to MIS5e. A stronger than presently Brazil warm current, reaching Southern latitudes, may explain the changes in geographical ranges. |
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| Keywords: | Mollusks Paleoecology Biogeography MIS 5e Pleistocene Argentina |
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