Mid-Atlantic 70,000 Year Dust Deposition Fluxes Middleton, J.L.; Mukhopadhyay, S.; Langmuir, C.H.; McManus, J.F.; Huybers, P.J. Middleton, J.L. Mukhopadhyay, S. Langmuir, C.H. McManus, J.F. Huybers, P.J. earth science/paleoclimate/paleocean (KN207-2-GGC6>LATITUDE 29.21>LONGITUDE -43.23) (KN207-2-GGC3>LATITUDE 26.14>LONGITUDE -44.8) Sedimentary records of dust deposition in the subtropical Atlantic provide important constraints on millennial- and orbital-scale variability in atmospheric circulation and North African aridity. Constant flux proxies, such as extraterrestrial helium-3, yield dust flux records that are independent of the biases caused by lateral sediment transport and limited resolution that may be associated with age-model-derived mass accumulation rates. However, Atlantic dust records constrained using constant flux proxies are sparsely distributed and generally limited to the past 20 ka. Here we extend the Atlantic record of North African dust deposition to 70 ka using extraterrestrial helium-3 and measurements of titanium, thorium, and terrigenous helium-4 in two sediment cores collected at 26N and 29N on the Mid-Atlantic Ridge and compare results to model estimates for dust deposition in the subtropical North Atlantic. Dust proxy fluxes between 26N and 29N are well correlated, despite variability in lateral sediment transport, and underscore the utility of extraterrestrial helium-3 for constraining millennial-scale variability in dust deposition. Similarities between Mid-Atlantic dust flux trends and those observed along the Northwest African margin corroborate previous interpretations of dust flux variability over the past 20 ka and suggest that long distance transport and depositional processes do not overly obscure the signal of North African dust emissions. The 70 ka Mid-Atlantic record reveals a slight increase in North African dustiness from Marine Isotope Stage 4 through the Last Glacial Maximum and a dramatic decrease in dustiness associated with the African Humid Period. On the millennial-scale, the new records exhibit brief dust maxima coincident with North Atlantic cold periods such as the Younger Dryas, and multiple Heinrich Stadials. The correlation between Mid-Atlantic dust fluxes and previous constraints on North African aridity is high. However, precipitation exerts less control on dust flux variability prior to the African Humid Period, when wind variability governs dust emissions from consistently dry dust source regions. Thus, the Mid-Atlantic dust record supports the hypothesis that both aridity and wind strength drive dust flux variability across changing climatic conditions. STUDY NOTES: Dust flux data plus helium, titanium, and thorium measurements for 2 mid Atlantic sediment cores for the past 70,000 years NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Middleton, J.L. Investigator : Mukhopadhyay, S. Investigator : Langmuir, C.H. Investigator : McManus, J.F. Investigator : Huybers, P.J. 2018-12-18 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/25870 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/middleton2018/middleton2018kn207-2-ggc3.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/middleton2018/middleton2018kn207-2-ggc6.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/middleton2018/middleton2018kn207-2-ggc3.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/middleton2018/middleton2018kn207-2-ggc6.txt English https://www.ncdc.noaa.gov/paleo/study/25870 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/middleton2018/middleton2018kn207-2-ggc3.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/middleton2018/middleton2018kn207-2-ggc6.txt Jennifer L. Middleton, Sujoy Mukhopadhyay, Charles H. Langmuir, Jerry F. McManus, and Peter J. Huybers2018Millennial-scale variations in dustiness recorded in Mid-Atlantic sediments from 0 to 70 kaEarth and Planetary Science Letters48212-2210.1016/j.epsl.2017.10.034https://www.sciencedirect.com/science/article/pii/S0012821X17306027 START YEAR: 68800 cal yr BP * END YEAR: 500 cal yr BP -44.8 26.14 -43.23 29.21