Enhanced Saharan dust input to the Levant during Heinrich stadials

QUATERNARY SCIENCE REVIEWS

卷:186

Article

Torfstein, Adi^1,2  Goldstein, Steven L.^3,4  Stein, Mordechai^1,5 

[1] Hebrew Univ Jerusalem, Fredy & Nadine Herrmann Inst Earth Sci, IL-91904 Jerusalem, Israel

[2] Interuniv Inst Marine Sci, IL-88103 Elat, Israel

[3] Columbia Univ, Lamont Doherty Earth Observ, 61 Rt 9W, Palisades, NY 10964 USA

[4] Columbia Univ, Dept Earth & Environm Sci, 61 Rt 9W, Palisades, NY 10964 USA

[5] Geol Survey Israel, 30 Malkhe Israel St, IL-95501 Jerusalem, Israel

关键词: Dead sea;    Lake lisan;    Dust;    Sr-Nd-Pb isotopes;    Heinrich events;   

DOI  :  10.1016/j.quascirev.2018.01.018

来源: Elsevier

【 摘 要 】

The history of dust transport to the Levant during the last glacial period is reconstructed using the isotope ratios of Pb, Sr, Nd, and Hf in sediments of Lake Lisan, the last glacial Dead Sea. Exposed marginal sections of the Lisan Formation were sampled near Masada, the Perazim Valley and from a core drilled at the deep floor of the modern lake. Bulk samples and size fractions display unique isotopic fingerprints: the finest detritus fraction (<5 mu m) displays higher Sr-87/Sr-86 and lower epsilon Nd values (0.710-0.713 and -7.0 to -9.8, respectively) relative to the coarser fractions (5-20 mu m and <20 mu m; 0.708-0.710 and -3.4 to -8.3) and the bulk detritus samples (0.709-0.711 and -6 to -7.5). Similarly, the Pb-206/Pb-204, Pb-207/Pb-204 and Pb-208/Pb-204 ratios (18.26-19.02, 15.634-15.68, and 38.25-38.82, respectively) are systematically higher in the finest detritus fraction relative to corresponding coarser fractions and bulk samples. The Sr-87/Sr-86 and epsilon Nd values of the finest fraction correspond with those of atmospheric dust originating from the Sahara Desert, while those of the coarse fractions are similar to loess deposits exposed in the Sinai and Negev Deserts. Pronounced excursions in the Sr-Nd-Pb isotope ratios toward more Sahara like values coincide with the Heinrich (H) stadials 6, 5 and 1, reflecting significant increases in Saharan dust fluxes during regionally arid intervals, reflected by sharp lake level drops. Moreover, during H6 the dust came from different Saharan sources than during H1 and H5. While the relatively wet glacial climate in the Levant suppressed the transport of dust to the lake watershed, short-term hyper-arid spells during H-stadial intervals were accompanied by enhanced supply of fine Sahara dust to this region. (C) 2018 Elsevier Ltd. All rights reserved.

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