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. Thanks to its optimal location on the northern Brazilian margin,core MD09-3257 records both ocean circulation and atmospheric changes. Thelatter occur locally in the form of increased rainfall on the adjacentcontinent during the cold intervals recorded in Greenland ice and northernNorth Atlantic sediment cores (i.e., Greenland stadials). These rainfallevents are recorded in MD09-3257 as peaks in ln(Ti  ∕  Ca). New sedimentaryPa  ∕  Th data indicate that mid-depth western equatorial water masstransport decreased during all of the Greenland stadials of the last 40 kyr.Using cross-wavelet transforms and spectrogram analysis, we assess therelative phase between the MD09-3257 sedimentary Pa  ∕  Th andln(Ti  ∕  Ca) signals. We show that decreased water mass transport betweena depth of ∼1300 and 2300 m in the western equatorial Atlantic precededincreased rainfall over the adjacent continent by 120 to 400 yr atDansgaard–Oeschger (D–O) frequencies, and by 280 to 980 yr at Heinrich-likefrequencies. We suggest that the large lead of ocean circulation changes with respect tochanges in tropical South American precipitation at Heinrich-likefrequencies is related to the effect of a positive feedback involvingiceberg discharges in the North Atlantic. In contrast, the absence ofwidespread ice rafted detrital layers in North Atlantic cores during D–Ostadials supports the hypothesis that a feedback such as this was not triggered inthe case of D–O stadials, with circulation slowdowns and subsequent changesremaining more limited during D–O stadials than Heinrich stadials.

Relative timing of precipitation and ocean circulation changes in the western equatorial Atlantic over the last 45 kyr