PALEOENVIRONMENTAL INFERENCES FROM ALATE QUATERNARY MARINE SEQUENCE IN SAMBOROMBÓN BAY, BUENOS AIRES (SOUTH AMERICA)

ANGÉLICA BALLESTEROS PRADA; BERNASCONI EMILIANA

Edinbungo

Congreso; FORAMS 2018-Foraminifera in a Changing World; 2018

Universidad de Edinburgo

The successive glacial and interglacial events in the Quaternary influenced the position of the coastline and helped to model the Argentine continental margins. The coastal zone of Samborombón bay is an excellent example of the deposits originated by the transgressions of the Late Pleistocene and the Holocene. With the aim of better understanding the variations occurred during the Holocene, we carry out a preliminary analysis of the Holocene benthic foraminifers from a sequence of 258 cm length, located on the margin of Channel 15 (Samborombón bay). It was dated between 5900 ± 100 years BP(252 cm) and 5550 ± 120 years BP (128cm). The sediments analyzed are mostly composed by sand and silt-sized particles. Some intermediate levels are characterized by the abundance of bivalve and gastropod shells.The fauna of foraminifers is relatively abundant (̴150 per gram of bulk sediment), although not very diverse (≤10 species). The species identified mainly belong to Order Rotaliida. The assemblages were characterized by individual of Elphidiuma ff. poeyanum (Balkwill& Wright), Buccella peruviana (d´Orbigny), Ammonia parkinsoniana (d´Orbigny), Ammonia tepida Cushman, Elphidium gunteriCole, Quinqueloculina seminula (Linnaeus) and Buliminella elegantissima (d´Orbigny).