PALEOENVIRONMENTAL EVOLUTION DURING THE HOLOCENE IN THE NORTHEAST OF SAO PAULO STATE, BRAZIL

Palynological analysis, isotopic and charcoal fragments provided information about the climate change of the last 10.250 years BP in the northeastern portion of the State of Sdo Paulo. The samples were taken from the base of the studied trench with ages between 10.000 and 6.986 years BR They present C-4 vegetation with values delta C-13 around -14.3 parts per thousand, little presence of palynomorphs, and fragments of charcoal. The interval was interpreted as the result of the predominance of a drier climate than the current in the early Holocene (that lasted until the mid Holocene), under which paleofires already occurred. From mid Holocene to the present days, the predominance of C-4 and C-3 vegetation values to -20.86 parts per thousand, and the increase frequency of pollen grains (as Byrsonima and Didymopanax) indicating Cerrado (Brazilian Savannah) suggest that, in the interval of 2.096 years BP until the current days, the area has been covered by a mixed vegetation composed by elements of grassland and forest, indicating a regression of the grassland associated to wetter climate, which favors the "cerraddo" as cover vegetation.