Abstract
n PALYNOFACIES ANALYSIS IN HOLOCENIC SEDIMENTS OF QUADROS LAGOON, RIO GRANDE DO SUL PLAIN, BRAZIL. The interpretation of environmental changes during the Holocene on the North Rio Grande do Sul Coastal Plain, is based on the core QU-RS-B09 of Quadros lagoon record. The palynofacies analysis was carried out in 41 sedimentary samples along the 405 cm of the core, dated of 6.700 - 40 years BP at 375 cm deep and in 4.870 - 40 years BP 75 cm deep. Q-mode cluster analysis provided the identification of six groupings which stratigraphically plotted allowed the characterization of three intervals with palynofacies features corresponding to different environments in the holocenic evolution of the lagoon. Interval 1A, characterized by a palynofacies predominantly comprised of Amorphous Organic Matter (AOM), opaque and non-opaque phytoclasts, is associated to a Lagoon System in a Transgressive Phase. Interval 1B, whose palynofacies corresponds to opaque phytoclasts, MOA and non-opaque phytoclasts characterizes the Lagoon System and the Lagoon Maximum Transgressive (PGMT). Interval 2, predominantly comprised of AOM and Botryococcus braunii, characterizes the Lagoon System in a Regressive Phase, having an increase of pollen grains and spore percents towards the top, which characterizes conditions similar to the present coastal lake.
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