Paleoceanography with variations in productivity and water temperature in a core from the Campos Basin

Abstract

To infer changes in paleotemperature and marine productivity based in planktonic foraminifera results, samples from a piston core drilled in the continental slope of the Campos Basin were studied. Qualitative and quantitative studies were performed in 31 intervals of the core as well as the biostratigraphic zones were recognized. Episodes of appearance and disappearance of the menardiform plexus were considered. The genus Pulleniatina, in addition to other guide species, such as Globorotalia truncatulinoides, Gr. crassaformis, Globoconella inflata, and Globigerinella calida were also analyzed. It was possible to identify the Quaternary biozones: Z, Y, X and W. Most of the bioindicator species used to identify changes in paleoproductivity and paleotemperature presented congruent responses, showing more oligotrophic and warmer waters in the Holocene (Z zone) than to the previous Y zone (Late Pleistocene), considered glacial. However, in most of the Y zone, temperatures reconstructed at depths of 100m of the water column were below 20°C, indicating that deeper, nutrient-rich waters may have reached the photic zone during the last glacial period, increasing productivity. During the Y1A subzone, a productivity peak was recognized, which may be associated with the deglaciation period and a high contribution of nutrients from the erosion of the continent. Another peak in the Y2 subzone is associated with a period of water cooling. Zones X and W (Middle Pleistocene) showed higher variations in productivity and water temperature than the upper zones. Zone W, considered glacial, is the zone with the lowest temperature values and the highest productivity of the entire core.