Late Quaternary vegetational and climate dynamics in southeastern Brazil, inferences from marine cores GeoB 3229-2 and GeoB 3202-1

Abstract

Late Quaternary palaeoenvironments from southeastern (SE) Brazil have been reconstructed by pollen analysis of two marine sediment cores. The core GeoB 3229-2 (19°38′5″S, 38°43′0″W, 780 mbsl) from the central depression south of the Abrolhos Bank is 505 cm long and >80 kyr BP old. The core GeoB 3202-1 (21°37′0″S, 39°58′7″W, 1090 mbsl) from the upper continental slope off Rio Paraı́ba do Sul is 495 cm long and 52 kyr BP old. Chronological control for core GeoB 3202-1 is based on seven AMS radiocarbon dates from individuals of the foraminiferal species Globigerinoides sacculifer. The age scale for core GeoB 3229-2 was obtained by the detailed correlation of the oxygen isotope and X-ray fluorescence records of both cores. The two marine pollen records document vegetational changes in the drainage areas of two major SE Brazilian rivers, the Rio Doce and the Rio Paraı́ba do Sul, which probably transported most of the pollen and spores deposited in the marine sediments. During glacial times grassland vegetation dominated the landscape and Atlantic rainforest and semideciduous forest were markedly reduced. Small areas of subtropical Araucaria forest occurred in southeastern (SE) Brazil, while cerrado vegetation was rare. Maximal grassland expansion and Atlantic rainforest reduction were found during the last glacial maximum, reflecting cold and relatively dry climatic conditions. During the late-glacial period grassland decreased and lowland forest taxa increased, indicating wetter and warmer conditions. Comparison between the two marine pollen records with terrestrial records from the two river drainage areas confirms that grassland dominated the glacial age landscape reconstructed from terrestrial records.