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Luminescence dated Late Pleistocene wave-built terraces in northeastern Brazil

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      Abstract

      This study presents field and chronological investigations along the coast of northeastern Brazil from ~4°S to 9°S latitude, which corresponds to ~700 km of coastline under a semi-diurnal mesotidal regime. We investigated wave-built terrace deposits and dated sediments using the optically stimulated luminescence and thermoluminescence methods on quartz grains. The wave-built terraces yielded two main age groups: 200-230 ka and 100-130 ka, which we interpreted as depositional ages. We correlated these age groups with oxygen-isotope stages 7c and 5e, respectively. These events correspond to the antepenultimate and penultimate transgressions along the Brazilian coast. The deposits occur mainly in patches on low-lying flat plateaus along the littoral zone and incision valleys that cut across coastal tablelands. The altitude of the base of the 200-230 ka terraces ranges from 10 m above mean sea level (asl) to -2m asl, whereas the base of the 100-130 ka varies from 12 m asl to -2 m asl. Both terraces were deposited in the foreshore and upper shoreface zones. We noted a coincidence between sea-level highstand chronologies in northeastern Brazil and those in the Bahamas and Bermuda.

      Translated abstract

      Este estudo apresenta uma investigação de campo e geocronológica realizada ao longo da costa nordeste do Brasil entre ~4°S e 9°S de latitude, o que corresponde a ~700 km de costa submetida a um regime de meso-maré. Nós investigamos terraços marinhos construídos por ondas e datamos sedimentos usando luminescência oticamente estimulada e termoluminescência em grãos de quartzo. Os terraços marinhos forneceram dois grupos de idades: 200-230 ka e 100-130 ka, que interpretamos como idades de deposição. Nós correlacionamos estas idades com idades do estágio isotópico do oxigênio 7c e 5e, respectivamente. Estes eventos correspondem a antepenúltima e penúltima transgressões que ocorreram ao longo da costa brasileira. Os depósitos ocorrem predominantemente em faixas sobre plateaus horizontais e de baixa altitude ao longo da zona litorânea e em vales incisos que cortam os tabuleiros costeiros. A altitude da base dos terraços de 200-230 ka varia entre 10 m e -2 m anm (acima do nível do mar), enquanto a base do terraço de 100-130 ka varia entre 12 m e -2 m anm. Ambos os terraços foram depositados na zona de frente de praia e zona de antepraia superior. Nota-se umaa coincidência entre a cronologia de níveis marinhos elevados no nordeste do Brasil e aquelas das Bahamas e Bermudas.

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      Most cited references 34

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      Climatologia do Brasil

       E Nimer,  E. NIMER,  N Nimer (1979)
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        Evolution of Atlantic-Pacific δ13C gradients over the last 2.5 m.y.

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          Climatologia do Brasil

           E Nimer,  E. NIMER,  Nimer (1989)
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            Author and article information

            Affiliations
            [1 ] Universidade de São Paulo Brazil
            [2 ] Universidade Federal do Rio Grande do Norte Brazil
            [3 ] Universidade Federal de Pernambuco Brazil
            Contributors
            Role: ND
            Role: ND
            Role: ND
            Journal
            aabc
            Anais da Academia Brasileira de Ciências
            An. Acad. Bras. Ciênc.
            Academia Brasileira de Ciências (Rio de Janeiro )
            1678-2690
            September 2011
            : 83
            : 3
            : 907-920
            S0001-37652011000300011

            http://creativecommons.org/licenses/by/4.0/

            Product
            Product Information: SciELO Brazil
            Categories
            MULTIDISCIPLINARY SCIENCES

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