@article{090add61117c41ec92edb09d55a23bfc,
title = "Hydrological and thermodynamic controls on late Holocene gypsum formation by mixing saline groundwater and Dead Sea brine",
abstract = "The rapid retreat of the Dead Sea during the past four decades led to the exposure of unique structures of massive gypsum along the shores. Many of these structures (having the shape of mounds) are associated with the activity of Ein Qedem-type saline springs that currently discharge Ca-chloride brine to the lake. Field observations, radiocarbon dating of aragonite (within the gypsum mounds) that yield ancient ages, and the narrow range of δ34S and δ18O values (δ34Sgyp: 14.1–16.9‰; δ18Ogyp: 14.4–16.5‰) indicates that the formation of the gypsum structures is related to the mixing of brines: the Dead Sea brine and ancient (last glacial) Ein Qedem type brine. These are Ca-chloride brines having different salinities and sulfur concentrations that satisfy conditions of an outsalting process whereby supersaturation of gypsum is attained by the mixing of these two brines in the offshore shallow water environment. Thermodynamic calculations (using the PHREEQC software) show that gypsum outsalting occurred when both brines were enriched with sulfate as compared to the present. The Ein-Qedem brine had higher sulfate when subjected to less intensive bacterial sulfate reduction. The Dead Sea was characterized by higher sulfate concentrations during intervals of low lake stands. The conditions of higher sulfate concentrations and enhanced discharge of the saline springs occurred repeatedly in the Dead Sea between ∼6.6 to 0.6 ka and were intermittent with periods of enhanced supply of sulfate to the lake by freshwaters.",
keywords = "Brines, Dead Sea, Hydroclimate, Lacustrine Gypsum, Outsalting, Saline springs, Thermodynamic modeling",
author = "Nurit Weber and Gilad Antler and Boaz Lazar and Mordechai Stein and Yoseph Yechieli and Ittai Gavrieli",
note = "Funding Information: We thank the staff of the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA, for providing the first author (NW) working space, helping her in the submission of a successful travel grant and the analytical process. We thank Navot Morag from the Geological Survey of Israel for helping with the quantitative XRD analyses. We thank the Godwin Laboratory for Paleoclimate Research for analysis of the sulfur and oxygen isotopic composition of gypsum, which was funded through NERC grant NE/S001344/1 to A. V. T. We thank the BSF Rahamimoff Travel Grant for Young Scientists, which funded the travel expenses of NW to NOSAMS. The study was supported by the PALEX project “Paleohydrology and Extreme Floods from the Dead Sea ICDP Core”, funded by the DFG, Germany (Grant No. BR2208/13-1/-2 to BL and MS) Grants from ISF Center of Excellence (up to end of 2019) and ISF 695/19 (from the end of 2019) to BL and by funds of the Israeli Government under GSI Dead Sea project #40573. Finally, we thank the associate editor and the referees for their comprehensive work that substantially improved the manuscript. Funding Information: We thank the staff of the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA, for providing the first author (NW) working space, helping her in the submission of a successful travel grant and the analytical process. We thank Navot Morag from the Geological Survey of Israel for helping with the quantitative XRD analyses. We thank the Godwin Laboratory for Paleoclimate Research for analysis of the sulfur and oxygen isotopic composition of gypsum, which was funded through NERC grant NE/S001344/1 to A. V. T. We thank the BSF Rahamimoff Travel Grant for Young Scientists, which funded the travel expenses of NW to NOSAMS. The study was supported by the PALEX project ?Paleohydrology and Extreme Floods from the Dead Sea ICDP Core?, funded by the DFG, Germany (Grant No. BR2208/13-1/-2 to BL and MS) Grants from ISF Center of Excellence (up to end of 2019) and ISF 695/19 (from the end of 2019) to BL and by funds of the Israeli Government under GSI Dead Sea project #40573. Finally, we thank the associate editor and the referees for their comprehensive work that substantially improved the manuscript. Publisher Copyright: {\textcopyright} 2021 Elsevier Ltd",
year = "2022",
month = jan,
day = "1",
doi = "10.1016/j.gca.2021.10.002",
language = "English",
volume = "316",
pages = "363--383",
journal = "Geochimica et Cosmochimica Acta",
issn = "0016-7037",
publisher = "Elsevier Ltd.",
}