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Ordovician seawater composition : evidence from fluid inclusions in halite

Meng F., Zhang Y., Galamay A. R., Bukowski K., Ni P., Xing E., Ji L.

Geological Quarterly

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2018

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Vol. 62, No. 2

344--352

EN

Fluid inclusions in halite can directly record the major composition of evaporated seawater; however, Ordovician halite is very rare. The Ordovician is a key time during the evolution history because profound changes occurred in the planet’s ecosystems. Marine life was characterized by a major diversification, the Great Ordovician Biodiversification Event and the Late Ordovician Mass Extinction, the first of the “big five” mass extinctions. However, so far there is no data on the Ordovician seawater. Data from the Ordovician-Silurian boundary were available only. In this study, we report the major compositions from Middle Ordovician halite in China to give the exact composition of Ordovician seawater. The basic ion composition (K+, Mg2+, Ca2+, and SO42-) of inclusion brines was established with the use of ultramicrochemical analysis. The data on the chemical composition of the brines in the primary inclusions indicated that the brines were of Na-K-Mg-Ca-Cl (Ca-rich) type, and cover a huge gap in the evolution of seawater chemistry. The chemical composition of the primary inclusion brine in halite confirmed the earlier results for the Cambrian and Silurian halite originating from other salt basins and the previous speculation of “calcite sea” during the Ordovician, indicating a higher potassium content in the Lower Paleozoic seawater than in the seawater of other periods of the Phanerozoic.

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The sulphur and oxygen isotopic composition of anhydrite from the Upper Pechora Basin (Russia) : new data in the context of the evolution of the sulphur isotopic record of Permian evaporites

Galamay A. R., Meng F., Bukowski K., Ni P., Shanina S. N., Ignatovich O. O.

Geological Quarterly

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2016

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Vol. 60, No. 4

990--999

EN

This study describes a new determination of the S and O isotope composition of Lower Permian (Kungurian) anhydrites from the Upper Pechora Basin, Cis-Ural region, Russia. δ34S values in sulphate facies vary from +13.7 to +15.1‰; and δ18O values range from +9.3 to +10.4‰. The values of d34S and d18O of anhydrite from halite facies varies from +12.6 to +15.0‰ and +7.5 to +10.9‰ respectively. The quantitative ratio of pyrite content from the water-insoluble residue (silty-sand fraction) is characterized by extremely low (<<1%) to high (4–5%) steep gradation values. The increased presence of pyrite indicates the influence of bacterial sulphate reduction. The sulphate reduction process was more intense, especially when evaporites were formed in mud. The narrow fluctuation range of sulphur and oxygen isotopes values of the measured anhydrite indicates low levels of fractionation. It was established that during the Permian, evolutionary changes in the content of sulphate ions in sea water correlate with the sulphur isotopic composition of marine evaporites

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Sulphur isotopes in anhydrites from Badenian (Middle Miocene) salts of Hrynivka area (Ukrainian Carpathian Foredeep)

Galamay A. R., Meng F., Bukowski K.

Geological Quarterly

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2014

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Vol. 58, No. 3

439--448

EN

Ten new determinations of the stable sulphur isotope content of anhydrite from Badenian rock salt in the Hrynivka 525 borehole (Ukrainian Carpathian Foredeep) show that δ34S values in anhydrite range from +20.2 to +22.7‰ and the average value of δ34S is +21.4 ± 0.3‰. Those values are similar to those of the Neogene marine sulphates. Comparison to other geochemical data (chemical composition of the brine contained in fluid inclusions and the bromine content in halite) suggests that the Badenian Carpathian Foredeep evaporite basin was supplied predominately by seawater solutes where, at different stages of salt accumulation, the influence of continental waters with lighter isotopic compositions of dissolved sulphate was important. The isotopic composition of sulphur (δ 34S) of Badenian seawater, calculated on the basis of sixty analyses of anhydrite related to halite of the Carpathian Region, is approximately +20.3‰, this value being similar to the sulphur isotopic composition of present-day seawater. The δ 34S value for Badenian seawater may have been slightly higher if we consider potential changes of the brine composition of salt-bearing basins caused by inflow of continental waters enriched in light 32S isotopes.

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Skład chemiczny badeńskich solanek z pierwotnych ciekłych inkluzji w halicie, basen zakarpacki (Ukraina)

Galamay A. R., Bukowski K.

Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2011

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T. 37, z. 2

245-267

PL

W strukturach wzrostowych halitu typu szewron w basenie zakarpackim (Ukraina) stwierdzono występowanie pierwotnych inkluzji, które mogą być pomocne przy określeniu składu chemicznego solanek badeńskiego basenu ewaporatowego. Ciekłe inkluzje występujące w sedymentacyjnym halicie badane były metodą analizy ultramikrochemicznej. Koncentracja solanek zakarpackiego basenu była wysoka - zbliżona do średniego etapu sedymentacji halitu. Zawartość jonów: K+ zawierała się w przedziale 10.6-17.6 g/l, Mg2+ w zakresie 31.4-58.3 g/l, a SO4 2- w przedziale 22.4-39.0 g/l. Na podstawie badań składu chemicznego głównych jonów stwierdzono, że solanki basenu zakarpackiego były nasycone względem halitu i podobne do solanek z innych badeńskich basenów.

EN

The primary fluid inclusions, which may be helpful in detemining the chemical composition of brines in the Badenian evaporite basin, were found in the chevron halite crystals from the Transcarpathian Basin (Ukraine). Fluid inclusions in sedimentary halite were examined with the use of ultra-microchemical analysis. Concentration of brines was high - close to the middle stage of halite sedimentation. The content of ions: K+ ranged from 10.6 g/l to 17.6 g/l, Mg2+ from 31.4 g/l to 58.3 g/l, and SO4 2- from 22.4 g/l to 39.0 g/l. Based on the chemical composition of major ions it was concluded that the brine from the Transcarpathian basin was saturated (to the stage of halite crystallization) and was similar to the Badenian brines from other basins.

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Origin of the Badenian salts from East Slovakian basin indicated by the analysis of fluid inclusions

Galamay A. R., Bukowski K., Poberezhskyy A. V., Karoli S., Kovalevych V. M.

Annales Societatis Geologorum Poloniae

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2004

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Vol. 74, No 3

267--276

EN

Chemical composition of the brines of primary fluid inclusions in sedimentary halite (from the boreholes: P-2, P-3, P-6, P-7 and P-8) of the Badenian evaporite of the Zbudza Fm. from East Slovakian basin indicates that the basinal brines belong to the Na-K-Mg-Cl-SO4 type. The ratios of K+, Mg2+, and SO42- ions are practically the same as they were in the Badenian seawater. Taking into account the information on the chemical evolution of seawater in the Phanerozoic (Kovalevich et al., 1998) and the calculations of this evolution for the Cenozoic (Zimmermann, 2000) it is suggested that the Badenian seawater was characterized by the reduced contents of Mg (by approximately 20%) and SO42- (by approximately 40%) in comparison with the recent seawater. The postsedimentary recrystallization of salts occurred under the effect of buried brines, which inherited their composition from the primary basinal brines. The intensive recrystallization of salts occurred during the tectonic movements.

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Temperature of halite-forming brines in the Badenian evaporite basins of the Carpathian region: fluid inclusion study

Galamay A. R.

Biuletyn Państwowego Instytutu Geologicznego

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1999

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nr 387

27--28