Paleoceanographic changes during the Oligocene in the South Atlantic have been examined using paleomagnetic, rock magnetic, carbonate content, and sediment accumulation rate (SAR) data. We show that magnetic susceptibility (MS) is largely controlled by carbonate content at Deep-Sea Drilling Project site 522, which in turn is the primary control on SAR at the site. Over 5000 MS measurements were averaged over magnetostratigraphic polarity intervals for use as indicators of carbonate content and SAR proxies. The study produced three primary results: (1) a spectral analysis of the MS data from one upper Oligocene core reveals two dominant periodicities (44.7 +/- 10.4 kyr and 26.4 +/- 3.6 kyr) which approximate Milankovitch obliquity (41 kyr) and precession (23 kyr) periods: (2) four pulses of increased SAR lasting 1 to 2 m.y. punctuate the section, implying longer-term climatic changes (these events are also seen in the Contessa quarry section of the Italian (Tethyan) Oligocene); and (3) two of the SAR maxima correspond to times of global cooling and possible ice volume increases, at 31 and 36 Ma.

Supplement to: Mead, Gregory; Tauxe, Lisa; LaBrecque, John L (1986): Oligocene paleoceanography of the South Atlantic: paleoclimatic implications of sediment accumulation rates and magnetic susceptibility measurements. Paleoceanography, 1(3), 273-284