We carried out oxygen and carbon isotope studies on monospecific foraminifer samples from DSDP Sites 522, 523, and 524 of Leg 73 in the central South Atlantic Ocean. The oxygen isotope ratios show a warming of 2 to 3 °C in bottom water and 5°C in surface water during the Paleocene and early Eocene. The carbon isotope values indicate strong upwelling during the early Eocene. The 1% increase in the d18O values of benthic and planktonic foraminifers at Site 523 in the later middle Eocene we ascribe to changes in the pattern of the evaporation and precipitation. The changes may be due to the worldwide Lutetian transgression. The oxygen ratios for the benthic and planktonic foraminifers indicate a cooling at the Eocene/Oligocene transition. The maximum temperature drop (5°C for benthic and 3°C for planktonic foraminifers) is recorded slightly beyond the Eocene/Oligocene boundary and took place over an interval of about 100,000 yr. The pattern of currents in the Southern Hemisphere was mainly structured by a precursor of the subtropical convergence during the Paleocene to late Eocene. The cooling at the Eocene/Oligocene transition led to drastic changes in the circulation pattern, and a precursor of the Antarctic convergence evolved.
Supplement to: Oberhänsli, Hedi; McKenzie, Judith A; Toumarkine, M; Weissert, Helmut J (1984): A paleoclimatic and paleoceanographic record of the Paleogene in the Central South Atlantic (Leg 73, Sites 522, 523, and 524). In: Hsü, KJ; LaBrecque, JL; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 73, 737-747, doi:10.2973/dsdp.proc.73.134.1984
