Geochemical Characterization of Holocene Sediments of Santo André Alluvial Plains (SW Portugal)

Sandra C. C. Moreira – sandraccmoreira@gmail.com (Universidade de Lisboa, Faculdade de Ciências, Departamento e Centro de Geologia, ed. C6, 3º piso, Campo Grande, 1749-016 Lisboa, Portugal)
Maria C.P. Freitas – cfreitas@fc.ul.pt (same address as S.C.C. Moreira)
Maria F. Araújo – faraujo@itn.pt (Instituto Tecnológico e Nuclear, Departamento de Química, Grupo de Química Analítica e Ambiente, Estrada Nacional 10, 2686-953, Sacavém, Portugal)
César Andrade – candradre@fc.ul.pt (same address as S.C.C. Moreira)
Anabela G. Cruces – acruces@fc.ul.pt (same address as S.C.C. Moreira)
e-Terra
volume 5 - nº 10 - 2008

e-terra.geopor.pt

Key-words: Holocene evolution, paleoenvironmental reconstruction, sedimentary record, geochemistry, coastal lagoon.

Abstract: A paleoenvironmental reconstruction of Santo André lagoon area throughout the Holocene is presented based upon sedimentological and geochemical study of two cores – “Cerradinha 14” and “LSA”, which were taken from the infill of adjacent alluvial plains.
The results of textural analysis (coarse fraction), composition (organic matter) and geochemistry (major, minor and trace elements – Si, Al, Fe, Ca and Cl) allowed the identification of four major lithostratigraphic units, present in both cores, corresponding to a time succession of distinct sedimentary environments – marine, lagoonal and fluvial - in the last 10000 years.

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