Climate variability at the southern boundaries of the Namib (southwestern Africa) and Atacama (northern Chile) coastal deserts during the last 120,000 yr |
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| Authors: | Jan-Berend W Stuut Frank Lamy |
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| Institution: | aResearch Center Ocean Margins, Bremen University, Bremen 28334, Germany;bGeoForschungsZentrum (GFZ) Potsdam Telegrafenberg, Haus C, Potsdam 14473, Germany |
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| Abstract: | In this study, we present grain-size distributions of the terrigenous fraction of two deep-sea sediment cores from the SE Atlantic (offshore Namibia) and from the SE Pacific (offshore northern Chile), which we ‘unmix’ into subpopulations and which are interpreted as coarse eolian dust, fine eolian dust, and fluvial mud. The downcore ratios of the proportions of eolian dust and fluvial mud subsequently represent paleocontinental aridity records of southwestern Africa and northern Chile for the last 120,000 yr. The two records show a relatively wet Last Glacial Maximum (LGM) compared to a relatively dry Holocene, but different orbital variability on longer time scales. Generally, the northern Chilean aridity record shows higher-frequency changes, which are closely related to precessional variation in solar insolation, compared to the southwestern African aridity record, which shows a remarkable resemblance to the global ice-volume record. We relate the changes in continental aridity in southwestern Africa and northern Chile to changes in the latitudinal position of the moisture-bearing Southern Westerlies, potentially driven by the sea-ice extent around Antarctica and overprinted by tropical forcing in the equatorial Pacific Ocean. |
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| Keywords: | Late Quaternary Chile Atacama Desert southwestern Africa Namib Desert Aridity Grain size End-member modeling Southern Westerlies |
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