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.
Original language | English |
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Article number | 118403 |
Number of pages | 9 |
Journal | Earth and Planetary Science Letters |
Volume | 622 |
Early online date | 3 Oct 2023 |
DOIs | |
Publication status | Published - 15 Nov 2023 |
Keywords
- Boron cycle
- Boron isotope
- Seawater evolution
- Plicoene Sedom Lagoon
- Pleistocene Lake Lisan
- Lacustrine authigenic aragonites