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PALYNOLOGICAL STUDIES OF LATE HOLOCENE JURUJUBA SOUND SEDIMENTS (GUANABARA BAY), RIO DE JANEIRO, SOUTHEAST BRAZIL
Sediments
Guanabara Bay
Late Holocene
Palaeoenvironment
Sea level variations
Author
Affilliation
Universidade Federal Fluminense. Instituto de Geociências. Departamento de Geologia Marinha. Laboratório de PaleoEcologia Tropica. Niterói, RJ, Brasil.
Universidade Federal Fluminense. Instituto de Geociências. LAGEMAR. Niterói, RJ, Brasil.
Universidade Federal do Rio de Janeiro. Departamento de Geologia. Laboratório de Análise Micropaleontológica - MicroCentro. Rio de Janeiro, RJ, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.
Universidade Federal Fluminense. Instituto de Geociências. LAGEMAR. Niterói, RJ, Brasil.
Universidade Federal do Rio de Janeiro. Departamento de Geologia. Laboratório de Análise Micropaleontológica - MicroCentro. Rio de Janeiro, RJ, Brasil.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.
Abstract
The Late Holocene vegetation history and climate fromsouthern (SE) Brazil have been reconstructed bymeans of
a pollen analysis of a 223 cm-long core fromthe central part of Jurujuba Sound (22°55256S and 43°06346W). The
analysis showed that before 3520 yr BP (subzone Ia), tropical rainforest occupied extensive parts of the
region. However, from 3520 yr BP onwards, the forest reduced in size and there was a slight increase in pollen
from hygrophyte plants, fern spores and algae. The higher sea level during this period favoured the expansion
of these plants, as well as Botryococcus, in the flooded areas around the Sound. There was a reduction in
palynomorph concentrations at about 2820 yr BP (subzone Ib). This can probably be related to a regressive
event of the relative sea level and the reduction of atmospheric precipitation during this period. This event
favoured an increase in grassland formations, and pioneer forest elements seemed to settle in the open areas.
The intensive human occupation in the region around Jurujuba Sound was clearly evident in the pollen record
next to the core top (at zone II). The low percentage of tree pollen grains showed that the Atlantic rainforest
was significantly reduced in size, while there was an expressive increase in the herbaceous pollen that is associated
with the appearance of exotic taxa.
Keywords
Pollen analysisSediments
Guanabara Bay
Late Holocene
Palaeoenvironment
Sea level variations
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