The magnitude, timing and abruptness of changes in North African dust deposition over the last 20,000 yr

D. McGee*, P. B. deMenocal, G. Winckler, J. B W Stuut, L. I. Bradtmiller

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Reconstructions of eolian dust accumulation in northwest African margin sediments provide important continuous records of past changes in atmospheric circulation and aridity in the region. Existing records indicate dramatic changes in North African dust emissions over the last 20ka, but the limited spatial extent of these records and the lack of high-resolution flux data do not allow us to determine whether changes in dust deposition occurred with similar timing, magnitude and abruptness throughout northwest Africa. Here we present new records from a meridional transect of cores stretching from 31°N to 19°N along the northwest African margin. By combining grain size endmember modeling with 230Th-normalized fluxes for the first time, we are able to document spatial and temporal changes in dust deposition under the North African dust plume throughout the last 20ka. Our results provide quantitative estimates of the magnitude of dust flux changes associated with Heinrich Stadial 1, the Younger Dryas, and the African Humid Period (AHP; ~11.7-5ka), offering robust targets for model-based estimates of the climatic and biogeochemical impacts of past changes in North African dust emissions. Our data suggest that dust fluxes between 8 and 6ka were a factor of ~5 lower than average fluxes during the last 2ka. Using a simple model to estimate the effects of bioturbation on dust input signals, we find that our data are consistent with abrupt, synchronous changes in dust fluxes in all cores at the beginning and end of the AHP. The mean ages of these transitions are 11.8±0.2ka (1σ) and 4.9±0.2ka, respectively.

Original languageEnglish
Pages (from-to)163-176
Number of pages14
JournalEarth and Planetary Science Letters
Publication statusPublished - 1 Jun 2013


  • Th normalization
  • Abrupt change
  • African Humid Period
  • Deglaciation
  • Eolian dust
  • North Africa


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