The chemical evolution of brine and Mg-K-salts along the course of extreme evaporation of seawater – An experimental study

Shalev, Netta; Lazar, Boáz; Köbberich, Michael; Halicz, Ludwik; Gavrieli, Ittai

doi:10.1016/j.gca.2018.09.003

Cited by 31 publications

(36 citation statements)

References 29 publications

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“…Thus, kainite may be of primary origin precipitated from the brine, or they may have been recrystallized from other K-Mg salt minerals such as sylvite (KCl), carnallite (KCl•MgCl 2 •6H 2 O), or kieserite (MgSO 4 •H 2 O) (Stewart 1963). Either primary or secondary in origin, their presence at least indicates that the salinity of the brine in the Caltanissetta basin exceeded the saturation point of the K-Mg salts during the MSC peak, which is over 70 times concentration of the seawater (Warren 2016;Shalev et al 2018).…”

Section: Sedimentary Facies and Spatial Distribution Of Elements Of Umentioning

confidence: 99%

“…Theoretically, the halites and K-Mg salts composing the Unit B K-Mg salt layer could have co-precipitated from a homogenous brine, because both halite and K-Mg salts can precipitate from brine concentrated over 70 times upon evaporation from the normal seawater (Warren 2016; Shalev et al 2018). However, this is unlikely considering the presence of hopanes and steranes (Figs.…”

Section: Depositional Environment Of Unit B K-mg Salt Layermentioning

confidence: 99%

“…Moreover, the transitions in the state and compositions of the microbial communities may in turn strongly affect the chemical characteristic of the evaporating brine. For example, biological activity strongly influences the CO 2 exchange between the brine and the atmosphere (Lazar et al 1992;Isaji et al 2017), and organic matter concentrated in the brine reduces the evaporation rate and the degree of evaporation that the brine can reach (Shalev et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Biomarker records and mineral compositions of the Messinian halite and K–Mg salts from Sicily

Isaji

Yoshimura

Kuroda

et al. 2019

Prog Earth Planet Sci

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The evaporites of the Realmonte salt mine (Sicily, Italy) are important archives recording the most extreme conditions of the Messinian Salinity Crisis (MSC). However, geochemical approach on these evaporitic sequences is scarce and little is known on the response of the biological community to drastically elevating salinity. In the present work, we investigated the depositional environments and the biological community of the shale-anhydrite-halite triplets and the K-Mg salt layer deposited during the peak of the MSC. Both hopanes and steranes are detected in the shale-anhydrite-halite triplets, suggesting the presence of eukaryotes and bacteria throughout their deposition. The K-Mg salt layer is composed of primary halites, diagenetic leonite, and primary and/or secondary kainite, which are interpreted to have precipitated from density-stratified water column with the halite-precipitating brine at the surface and the brineprecipitating K-Mg salts at the bottom. The presence of hopanes and a trace amount of steranes implicates that eukaryotes and bacteria were able to survive in the surface halite-precipitating brine even during the most extreme condition of the MSC.

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Section: Sedimentary Facies and Spatial Distribution Of Elements Of Umentioning

confidence: 99%

Section: Depositional Environment Of Unit B K-mg Salt Layermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biomarker records and mineral compositions of the Messinian halite and K–Mg salts from Sicily

Isaji

Yoshimura

Kuroda

et al. 2019

Prog Earth Planet Sci

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“…These vary between the chloride type, composed mainly of sylvite and carnallite (Table 1), and the sulfate type, characterized by MgSO 4 -rich minerals (e.g., Zharkov, 1981;Hardie, 1991;Lowenstein et al, 2001;Babel and Schreiber, 2014). The sequence of marine Mg-evaporite minerals that precipitate along the course of evaporation depends not only on the chemical composition of the parent seawater, but also on the degree of enclosure of the basin, the precipitating brine's temperature, whether or not continuous reaction with the already precipitated salts is maintained, and if additional reactions within the evaporitic basin take place (e.g., Eugster et al, 1980;Harvie et al, 1980;McCaffrey et al, 1987;Shalev et al, 2018b). For example, when the precipitating salts are continuously separated from the brine (i.e., fractional precipitation) during the course of modern seawater evaporation at 25°C, the precipitating minerals include epsomite, kainite, carnallite, kieserite and bischofite (e.g., Eugster et al, 1980;Shalev et al, 2018b; Table 1).…”

Section: Introductionmentioning

confidence: 99%

“…The sequence of marine Mg-evaporite minerals that precipitate along the course of evaporation depends not only on the chemical composition of the parent seawater, but also on the degree of enclosure of the basin, the precipitating brine's temperature, whether or not continuous reaction with the already precipitated salts is maintained, and if additional reactions within the evaporitic basin take place (e.g., Eugster et al, 1980;Harvie et al, 1980;McCaffrey et al, 1987;Shalev et al, 2018b). For example, when the precipitating salts are continuously separated from the brine (i.e., fractional precipitation) during the course of modern seawater evaporation at 25°C, the precipitating minerals include epsomite, kainite, carnallite, kieserite and bischofite (e.g., Eugster et al, 1980;Shalev et al, 2018b; Table 1). But, when the evolving solution is allowed to react with previously precipitated salts over the course of the evaporation, the precipitating minerals include polyhalite, epsomite, hexahydrite, carnallite, kieserite and bischofite (e.g., Eugster et al, 1980; Table 1).…”

Section: Introductionmentioning

confidence: 99%

The Mg isotope signature of marine Mg-evaporites

Shalev

Lazar

Halicz

et al. 2021

Geochimica et Cosmochimica Acta

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Marine Mg-evaporites are a small oceanic sink of magnesium, precipitating only from extremely evaporated brines. The isotopic composition of Mg in seawater, d 26 Mg seawater , has recently been shown to be an effective tool for reconstructing the Mg budget of the modern and past oceans. However, estimations of the Mg isotope fractionation between the Mg-evaporites and their precipitating solution are required for full quantification of the isotope effect of the evaporitic sink on d 26 Mg seawater , as well as for utilizing ancient evaporitic sequences as an archive for past d 26 Mg seawater . Here, we estimate the Mg isotope fractionation between Mg-evaporites and modern marine-derived brine along the course of seawater evaporation, up to degree evaporation of >200. The sequence of Mg-salts included epsomite (The following isotope fractionation values, either negative or positive, were calculated from the isotope difference between the salt and its precipitating brine, and from the evolution of d 26 Mg in the brine throughout the evaporation: D carnallite-brine = +1.1‰, D epsomite-brine = +0.59‰, D bischofite-brine = +0.33‰, D kieserite-brine = À0.2‰ and D kainitebrine = À1.3‰. Magnesium isotopic compositions determined on minerals from different ages in the geological record corroborate well these results. Due to precipitation of multi-mineral assemblages having isotope fractionation values of opposing signs, the d 26 Mg value of the brine changes only slightly (<0.5‰) throughout the evaporation path, despite the considerable Mg removal (>50%). The isotope fractionations are shown to correlate with the number of water molecules coordinated to the Mg 2+ and with Mg-O bond length in the mineral lattice.Given these isotope fractionations, it is calculated that a volume of 0.4 Á 10 6 -0.8 Á 10 6 Km 3 of a mono-mineral assemblage of kainite or carnallite needs to precipitate in order to change seawater d 26 Mg by only 0.1‰. This huge volume is by far larger than the volume of these minerals known to date in the global geological record. Therefore, it is concluded that the impact of Mg-evaporites formation on d 26 Mg seawater has been insignificant since the Proterozoic. The results of this study suggest that the Mg isotopic composition of Mg-evaporites preserved in the geological record of evaporitic basins may be used to: 1) quantify geochemical processes that fractionate Mg-isotopes within these basins, such as dolomitization; and 2) complete the secular variations curve of the marine d 26 Mg record using basins with well-established evaporitic sequences.

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Paleoproterozoic Mississippi Valley-type mineralization at Black Angel, Greenland: evidence from sulfide δ66Zn and rhenium-osmium geochronology

Saintilan,

Archer,

Szilas

et al. 2024

Miner Deposita

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We provide timestamps for the major zinc-lead (Zn-Pb) Mississippi Valley-type Black Angel deposit (Greenland) based on new pyrite rhenium-osmium (Re-Os) isotope geochemistry data: (1) a Re-Os isochron age 1,884 ± 35 million years ago (Ma – 2σ, 1.8%) for subhedral pyrite cemented by sphalerite ± galena in dolomitized clean limestone, and, (2) a Re-Os model age 1,828 ± 16 Ma (2σ, 0.9%) for epigenetic massive pyrite in siltstone/mudstone cap rock. Zinc-lead mineralization in evaporite-bearing carbonates in the Karrat Basin took place ca. 1,884 Ma at the time of far-field fluid flow associated with back-arc spreading ca. 1,900–1,850 Ma. Mineralization predates the development of the Rinkian foreland basin (ca. 1,850 – < 1,800 Ma) and a collisional stage (ca. 1,830 – < 1,800 Ma) in the context of the telescoping Rinkian and the Nagssugtoqidian Orogens. Replacement of clean carbonate and sustained acid neutralization led to significant sphalerite precipitation ca. 1,884 Ma. Conversely, precipitation of epigenetic massive pyrite in the cap rock ca. 1,828 Ma may signal (1) the lack of chemical reactivity of the cap rock for the pH-buffered conditions needed for Zn-Pb mineralization, and (2) the unfavorable impact of incipient regional Rinkian metamorphism (ca. 1,830–1,800 Ma) and tectonic compression on aquifer permeability and continued brine migration. The initial 187Os/188Os ratio (Osi-pyrite = 1.07 ± 0.32) from isochron regression identifies a crustal origin for Os and, by corollary, other metals in the ca. 1,884 Ma Zn-Pb mineralization. Although the Rae Craton basement rocks comprise the dominant source for metals (based on our Osi-pyrite and δ66Znpyrite/sphalerite data), we identify a complementary contribution in Zn (maximum 12–24%) from Paleoproterozoic sedimentary carbonate. This source of Zn in sedimentary calcite is deemed possible in the context of Paleoproterozoic seawater at high Na/Cl ratio and in the absence of Zn-based eukaryotic metabolism in shallow marine environment.

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The chemical evolution of brine and Mg-K-salts along the course of extreme evaporation of seawater – An experimental study

Cited by 31 publications

References 29 publications

Biomarker records and mineral compositions of the Messinian halite and K–Mg salts from Sicily

Biomarker records and mineral compositions of the Messinian halite and K–Mg salts from Sicily

The Mg isotope signature of marine Mg-evaporites

Paleoproterozoic Mississippi Valley-type mineralization at Black Angel, Greenland: evidence from sulfide δ66Zn and rhenium-osmium geochronology

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