Changes in the flux of aeolian dust from South America to the Southern Ocean during past climate stages are suggested to have had significant impact on biogeochemical activity in these presently high-nutrient, low-chlorophyll waters , and resultant drawdown of atmospheric CO2.  A strong direct correlation exists between the records of Antarctic dust flux and the magnetic susceptibility of Southern Ocean sediments.  To identify  the source of the variations in sediment magnetic content and provenance, detailed mineral magnetic analyses have been performed on particle-sized fractions of both a subset of the sediment samples and a range of potential source materials, including present dust source areas in Patagonia and the Altiplano region, and marine sediments, spanning the W. Patagonian and Antarctic continental margins.  Quantitative source identification and attribution enables detailed estimation of past changes in dust fluxes, and their possible significance with regard to iron flux and pathways of atmospheric circulation.