The sea-level highstand correlated to marine isotope stage (MIS) 7 in the coastal plain of the state of Rio Grande do Sul, Brazil

Anais da Academia Brasileira de Ciências

Renato P. Lopes¹  Sergio R. Dillenburg¹  Cesar L. Schultz¹  Jorge Ferigolo¹  Ana Maria Ribeiro¹  Jamil C. Pereira¹  Elizete C. Holanda¹  Vanessa G. Pitana¹  Leonardo Kerber¹ 

关键词: Barrier II;    Chuí Creek;    MIS 7;    Pleistocene;    Paleoceanography;    Barreira II;    Arroio Chuí;    MIS 7;    Pleistoceno;    Paleoceanografia;   

DOI  :  10.1590/0001-3765201420130274

来源: SciELO

【 摘 要 】

The coastal plain of the state of Rio Grande do Sul, in southern Brazil, includes four barrier-lagoon depositional systems formed by successive Quaternary sea-level highstands that were correlated to marine isotope stages (MIS) 11, 9, 5 and 1, despite the scarcity of absolute ages. This study describes a sea-level highstand older than MIS 5, based on the stratigraphy, ages and fossils of the shallow marine facies found in coastal barrier (Barrier II). This facies outcrops along the banks of Chuí Creek, it is composed of fine, well-sorted quartz sand and contains ichnofossils Ophiomorpha nodosa and Rosseliasp., and molluscan shells. The sedimentary record indicates coastal aggradation followed by sea-level fall and progradation of the coastline. Thermoluminescence (TL) and electron spin resonance (ESR) ages from sediments and fossil shells point to an age of ∼220 ka for the end of this marine transgression, thus correlating it to MIS 7 (substage 7e). Altimetric data point to a maximum amplitude of about 10 meters above present-day mean sea-level, but tectonic processes may be involved. Paleoceanographic conditions at the time of the highstand and correlations with other deposits in the Brazilian coasts are also discussed.

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