Boron geochemistry reveals the evolution of Dead Sea brines
Abstract
Well-known for their geological and natural singularity, the Dead Sea brines evolved from a marine ingression of the Mediterranean during the Pliocene. Dead Sea brines are currently almost ten times more concentrated than seawater and have a unique chemical composition with high boron isotope values (Bbrine = ∼57‰). However, little is known on how these values were attained and their underlaying driving processes. Here we use boron isotopes (B) combined with B/Ca and B/Li of lacustrine authigenic aragonites from the deep basin drill-core ICDP 5017-1, and Ein Gedi and Masada profiles to reconstruct past brine conditions. Comparing reconstructed Bbrine from two key periods of contrasting hydro-climatic regimes we find that the brines of the late Holocene Dead Sea were enriched in 11B (Bbrine = ∼60‰) relative to its glacial precursor Lake Lisan (∼57‰). With the aid of boron cycle modelling, we quantify the main boron fluxes in the basin. We show that the post-glacial Bbrine enrichment is best explained by overall reduction of freshwater inflow to the lake and coeval increase in 10B sink through boron co-precipitation in evaporitic deposits and boron loss in atmospheric water vapour, consistent with the onset of warmer and drier climate in the Eastern Mediterranean during the Holocene. On geological time scales, adsorption of 10B on clastic sediments has acted as an important 10B sink and can explain the evolution of the high Bbrine values.
Citation
Jurikova , H , Ring , S , Henehan , M , Neugebauer , I , Schröder , B , Müller , D , Schwab , M , Tjallingii , R , Brauer , A & Blanchet , C 2023 , ' Boron geochemistry reveals the evolution of Dead Sea brines ' , Earth and Planetary Science Letters , vol. 622 , 118403 . https://doi.org/10.1016/j.epsl.2023.118403
Publication
Earth and Planetary Science Letters
Status
Peer reviewed
ISSN
0012-821XType
Journal article
Description
This project was funded by the German Research Foundation, DFG (Grant no. TJ 66/2-1, ‘Sediment provenance and past hydrological balance in the Dead Sea region during the Early Holocene’ - PRO-HYDRO) under Priority Programme 1006 ICDP, and was also supported by the DFG project PALEX (Grant no. BR2208/13-1/-2, ‘Paleohydrology and Extreme Floods from the Dead Sea ICDP core’).Collections
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