Análises faunística e multivariada de foraminíferos planctônicos da bacia Pernambuco-Paraíba: uma interpretação paleoambiental dos últimos 30 mil anos

Abstract

This study investigated the planktonic foraminifera of 23 samples from two sediment cores of the continental slope (between 1,260 and 1,315 m deep) of Pernambuco-Paraiba Basin (Brazil), western South Atlantic. For each sample, 300-600 specimens of foraminifers were identified. The relative abundance of species was calculated and then employed to statistical analysis. Recovered planktonic foraminifera assemblages represent a typical tropical association involving species of warm water, especially Globigerinoides ruber and Globigerinoides sacculifer. This dominance makes difficult the recognition of the relationship between environmental parameters and changes in abundance of other species. The results indicate relative stability of general environmental conditions over the last 30,000 years in the study area. The application of Q-mode factor analysis helped in the identification of the most significant factors for the planktonic foraminifera. Changes in the mixed layer and the temperature of the sea surface were considered the main environmental parameters that can influence the distribution of planktonic foraminifera recorded in the Pernambuco-Paraiba Basin. We believe that the dynamics of winds related to the Intertropical Convergence Zone infl uences the study area, both for charging the higher temperatures of the sea surface, as well as promoting greater or lesser vertical mixing of the ocean in this region.