CAMPANIAN PALYNOMORPHS (UPPER CRETACEOUS) FROM THE PELOTAS BASIN, RIO GRANDE DO SUL: BIOSTRATIGRAPHIC AND PALEOENVIRONMENTAL IMPLICATIONS

Abstract

This paper presents results of the palynological analyses carried out on core samples from the BP-01 well, drilled by PETROBRAS, offshore portion of the Pelotas Basin. They include seven samples from 4,480 to 4,487 m depth, with well preserved and varied palynological assemblages. Although not diversified, spores are the most abundant palynomorphs, dominated by species of Cicatricosisporites. On the other hand, cysts of dinoflagellates are less abundant but constitute the most diversified group, with 34 taxa, including 9 species previously unkown in the Brazilian marginal basins. Scarce palynoforaminifers, fungi, copepod eggs and prasinophycean acritarchs were also recorded. Dinocysts allow to assign this section to the Campanian (Upper Cretaceous). The palynological assemblages suggest a neritic environment, with relatively calm waters. A significant amount of spores, including several tetrads, indicates proximity to the continent. Furthermore, the biogeographic characteristics of certain cosmopolitan species of dinocysts confirm the interpretation of an open oceanic circulation pattern in the basin, linking waters from the northern and southern parts of the South Atlantic.