North African Dust Deposition Fluxes Over the last 20,000 years McGee, D.; deMenocal, P.B.; Winckler, G.; Stuut, J.-B.W.; Bradtmiller, L.I. McGee, D. deMenocal, P.B. Winckler, G. Stuut, J.-B.W. Bradtmiller, L.I. earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,null) earth science/paleoclimate/paleoceanography (age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (dust,sediment,null,percent,null,paleoceanography,null,null,N,detrital sediment) earth science/paleoclimate/paleoceanography (230Th,sediment,null,disintegration per minute per gram,null,paleoceanography,null,isotope dilution mass spectrometry,N,null) earth science/paleoclimate/paleoceanography (dust,sediment,null,gram per square centimeter per kiloyear,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (mineral matter,null,null,percent,null,paleoceanography,null,null,N,detrital/clastics only?) earth science/paleoclimate/paleoceanography (accumulation rate,sediment,null,gram per square centimeter per kiloyear,null,paleoceanography,null,null,N,sediment flux; Calculated by 230Thxs normalization using detrital U/Th activity ratio of 0.7 ± 0.1) earth science/paleoclimate/paleoceanography (accumulation rate,sediment,one standard deviation,gram per square centimeter per kiloyear,null,paleoceanography,null,null,N,sediment flux) earth science/paleoclimate/paleoceanography (232Th,sediment,null,disintegration per minute per gram,null,paleoceanography,null,isotope dilution mass spectrometry,N,null) earth science/paleoclimate/paleoceanography (238U,sediment,null,disintegration per minute per gram,null,paleoceanography,null,isotope dilution mass spectrometry,N,null) earth science/paleoclimate/paleoceanography (depth,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (OCE437-07-GC68>LATITUDE 19.363>LONGITUDE -17.282333) (OCE437-07-GC27>LATITUDE 30.879833>LONGITUDE -10.629833) (OCE437-07-GC49>LATITUDE 23.206167>LONGITUDE -17.854167) (OCE437-07-GC37>LATITUDE 26.81595>LONGITUDE -15.117717) (OCE437-07-GC66>LATITUDE 19.944>LONGITUDE -17.860217) 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 20 ka, 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 20 ka. 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; ~11.7-5 ka), 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 8-6 ka were a factor of ~5 lower than average fluxes during the last 2 ka. 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 ± 0.2 ka (1s) and 4.9 ± 0.2 ka, respectively. STUDY NOTES: Ages determined by P_Sequence routine in Oxcal 4.2. Uncertainties on sediment flux are dominated by correction for detrital 230Th. Dust fraction is sum of variables EM2 and EM1 contributions to detrital fraction. Dust flux calculated as sediment flux*detrital%*dust fraction. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : McGee, D. Investigator : deMenocal, P.B. Investigator : Winckler, G. Investigator : Stuut, J.-B.W. Investigator : Bradtmiller, L.I. 2014-04-29 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/16397 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc27-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc68-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc68-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc37-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc37-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc66-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc27-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc49-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc49-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc66-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc27-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc68-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc68-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc37-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc37-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc66-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc27-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc49-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc49-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc66-flux.txt English https://www.ncdc.noaa.gov/paleo/study/16397 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc27-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc68-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc68-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc37-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc37-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc66-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc27-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc49-grain.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc49-flux.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/mcgee2013/mcgee2013-gc66-flux.txt McGee, D., P.B. deMenocal, G. Winckler, J.B.W. Stuut and L.I. Bradtmiller2013The magnitude, timing and abruptness of changes in North African dust deposition over the last 20,000 yrEarth and Planetary Science Letters371-372163-17610.1016/j.epsl.2013.03.054 START YEAR: 21933 cal yr BP * END YEAR: 358 cal yr BP -17.860217 19.363 -10.629833 30.879833