WESTROP: Wechselwirkung zwischen Land und Meer sowie ihre Bedeutung fuer die Stoffkreislaeufe und Stromsysteme im westlichen tropischen Atlantik: Palaeozeanographie, Sedimentologie und Biogeochemie. Teilprojekt C: Palaeozeanographische Rekonstruktion des Brasil und Nord Brasil Stromes im Spaetquartaer Abschlussbericht

Abstract

Paleoceanographic studies on sediment cores from the upper continental slope of NE-Brazil, retrieved during R/V Victor Hensen cruise JOPS-II in spring '95, revealed high resolution climatic records of the last 85,000 years. Due to the influence from both continental processes and regional oceanography, these sediment records also present a good archive for the reconstruction of the history of land-ocean interactions. Using in total 35 AMS "1"4C ages and stable isotope records a detailed stratigraphical control was obtained. To reconstruct past oceanographic conditions we used X-ray fluorescence measurements, carbonate and organic carbon determinations of the bulk sediment and oxygen and carbon isotope measurements on the test of the planktonic foraminifera species Globigerinoides ruber (pink) and Globigerinoides sacculifer. Due to high sedimentation rates of the investigated cores and 2.5 to 5 cm sampling interval, the time resolution is about 100-500 years. We suggest that short termed climatic oscillations as described from Greenland and Antarctic ice core records and North Atlantic sediment cores are also documented in the marine records of low latitudes. A comparison of our sediment records with the GISP2 ice core signals reveals strong similarities. We assume that short termed variations in the atmospheric circulation, surface ocean currents, and sea level fluctuations during the isotope stages 2 to 4 are responsible for the modulation of the records. (orig.)Available from TIB Hannover: F98B222 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman