Terrigenous flux in the Rio Grande Rise area during the past 1500 ka: Evidence of deepwater advection or rapid response to continental rainfall patterns?

Surface sediment samples and three gravity cores from the eastern terrace o f the Vema Channel, the western flank of the Rio Grande Rise, and the Brazi lian continental slope were investigated for physical properties, grain siz e, and clay mineral composition. Discharge of the Rio Doce is responsible f or kaolinite enrichments on the slope south of 20 degrees and at intermedia te depths of the Rio Grande Rise. The long-distance advection of kaolinite with North Atlantic Deep Water from lower latitudes is of minor importance as evidenced by low kaolinite/chlorite ratios on the Mid-Atlantic Ridge. Cy clic variations of kaolinite/chlorite ratios in all our cores, with maxima in interglacials, are attributed to low- and high-latitude forcing of paleo climate on the Brazilian mainland and the related discharge of the Rio Doce . A longterm trend toward more arid and "glacial" conditions from 1500 ka t o present is superimposed on the glacial-interglacial cyclicity.