Holocene paleoenvironmental changes in the Bojuru Region, RS, Brazil: a multidisciplinary approach.

WESCHENFELDER, J.; MEDEANIC, S.; CORRÊA, I.; ALIOTTA, S.; PEREIRA, C.; DE VASCONCELLOS, V.

Guarapari, Brasil.

Congreso; X Congresso Brasileiro da ABEQUA (Associaçáo Brasileira de Estudos Quaternarios ); 2005

Associaçáo Brasileira de Estudos Quaternarios

Abstract. The reconstruction of the Holocene paleoenvironment in the Bojuru region, southern Brazil, was based on data from seismology, geochronology, sedimentology and palynology, and diatom analysis. Two absolute ages by 14C method were obtained (7370 ± 150 yr BP and 9400 ± 140 yr BP). Six stages of paleoenvironmental development were identified in the Bojuru region. Marine palynomorphs (acritarchs, dinoflagellates), and marine and estuarine diatoms are frequently observed in muddy sediments deposited during the Holocene. Analysis of the seismic records revealed a prominent paleochannel buried near the Bojuru town. The main channel incision was related to the last regressive event of the Late Pleistocene. During the Holocene transgression, this paleochannel was filled up with fluvial, estuarine and marine sediments. The integrated analysis of the different data reveals that the Barra Falsa geomorphologic feature resulted from a former paleochannel that connected the Patos Lagoon and the Atlantic Ocean. Keywords: Coastal evolution; Paleochannel; the Patos Lagoon