Palinomorfos e partículas de carvões nos sedimentos holocênicos na região do alto rio Paraná e sua aplicação nas reconstruções paleoambientais e paleoclimáticas

Abstract

The samples from two profiles of flood plain deposits of the Paraná River were studied. One sample at the depth of 1.95 m was dated by 14 C as 1,700 ± 70 yr BP. Palynological data and charcoal particles were obtained from fluvial sediments and paleosoil. Two principal stages in paleoenvironmental development were established. The early stage is characterized by the limited distribution of riparian forests and predominance of mesophyllous grassland under a condition of relatively dry climate. The deposition of charcoal particles in such predominant quantity was the result of local or regional burns. During the more recent stage, a natural enlargement of riparian forests occurred in conjunction with an increase in rainfall. Land use of that region may be confirmed by relatively frequent presence of pollen from cultivated, weed and introduced plants, encountered in sediments. The major frequency of charcoal particles occurred in the same samples was probably associated with anthropogenic activities during the last stage.