Barite mineralization in Kalana speleothems, Central Estonia: Sr, S and O isotope characterization

Gaškov, Mikk; Sepp, Holar; Paiste, Päärn; Kirsimäe, Kalle; Pani, Tõnu

doi:10.3176/earth.2017.10

Cited by 4 publications

(6 citation statements)

References 46 publications

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“…Finally, the enrichment in heavy S isotope data supports the organic origin of sulphur, which could be derived from i.e. thermal decomposition of organosulphur compounds in the limestones 33,41 . The relationship between δ 34 S and δ 18 O data of barite can be explained by the mixing of magmatic-hydrothermal sulphate with steam-heated SO4 from the oxidation of H2S near the earth surface 5…”

Section: Timing and Origin Of Barite Mineralizationmentioning

confidence: 54%

“…To determine the source of sulphate necessary for barite crystallization three potential alternatives were discussed: (1) direct dissolution of evaporites, (2) oxidation of sulphide minerals, or (3) mineralization of organic substance 41 . In Nador, evaporite deposits are not known to exist in the rock sequences of that area, so they could not be considered as a possible source of the sulphate.…”

Section: Timing and Origin Of Barite Mineralizationmentioning

confidence: 99%

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Origin of gem-quality barite at Jebel Ouichane district in Nador, Morocco: implications from integrated fluid inclusions, stable isotopes, and geochemistry

Dumańska-Słowik

Naglik

Toboła

et al. 2021

Preprint

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Light-blue barite from Jebel Ouichane in Morocco forms blade-like tabular crystals (up to ca. 10 cm) with superb transparency and lustre. It represents one of the most spectacular gem-quality specimens in the world. The barite is hosted by iron-ore-bearing skarns, developed within Jurassic-Cretaceous limestones, and occurs in close spatial association with calcite. Although it exhibits simple chemical composition, some irregular sectorial zoning, maintained by elevated contents of Sr in various crystal domains, were found. Barite from Ouichane is abundant in one phase (liquid or gas) or two-phase (liquid-gas) fluid inclusions of primary, pseudosecondary, and secondary origin. A combination of fluid inclusion microthermometry and stable isotope data suggest that δ18O value of barite-forming solutions, resulting from mixing of meteoric waters with hydrothermal fluids, could be in the range from -3,5‰ to +2,7 ‰ (VSMOW), whereas the main barite crystallization stage falls in the temperatures range of 160-180 °C. The recorded first ice melting temperatures (-35.9 to -41.5 ºC) indicate the presence of divalent cations, i.e. Ca2+and Mg2+ in addition to NaCl ± KCl in the mineralizing fluid composition. The possible source of SO42- and Ba2+, which gave rise to the barite formation was fluid enriched in Ba, Sr, Ca, Mg, S, and other elements derived from the alteration of carbonate and silicate minerals, being components of sedimentary and igneous rocks found in the surroundings of Nador area. Necessary amounts of sulphur could be in turn provided by weathering of pyrite and/or decomposition of organosulphur compounds. The combination of δ34S and δ18O values of barite (+16.39‰ and 6.71‰, respectively) indicate that its formation occurred in a steam-heated (near-surface) environment.

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Section: Timing and Origin Of Barite Mineralizationmentioning

confidence: 54%

Section: Timing and Origin Of Barite Mineralizationmentioning

confidence: 99%

Origin of gem-quality barite at Jebel Ouichane district in Nador, Morocco: implications from integrated fluid inclusions, stable isotopes, and geochemistry

Dumańska-Słowik

Naglik

Toboła

et al. 2021

Preprint

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“…On the other hand, both pyrite and barite may form contemporaneously, as a result of low-temperature hydrothermal activity. Finally, the enrichment in δ 34 S might suggest an organic origin related to the thermal decomposition of organosulphur in the limestones 42 , 51 . Alternatively, the relationship between both δ 34 S and δ 18 O data of barite provides evidence for the mixing of HSO 4 and SO 4 2- derived from magmatic-hydrothermal SO 2 with sulphates from the oxidation of H 2 S near the earth surface (steam-heated) conditions 6 , 50 , 52 .…”

Section: Discussionmentioning

confidence: 97%

“…The low solubility of this sulphate in hydrothermal conditions indicates that both main barite components were not transported together in one fluid 50 . To determine the source of sulphate necessary for barite crystallization we initially assume the following scenarios including (1) direct dissolution of evaporites, (2) oxidation of sulphide minerals, or (3) mineralization of organic substance 51 . In Nador, evaporite deposits are not known from the rock sequences in that area and thus cannot be considered as a possible source for SO 4 -rich fluids.…”

Section: Discussionmentioning

confidence: 99%

Origin and occurrence of gem-quality, skarn-hosted barite from Jebel Ouichane near Nador in Morocco

Dumańska-Słowik

Naglik

Toboła

et al. 2021

Sci Rep

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Light-blue barite from Jebel Ouichane in Morocco forms blade-like tabular crystals (up to ca. 10 cm) with superb transparency and lustre and represents one of the most spectacular gem-quality worldwide. The barite is hosted by iron-ore-bearing skarns, developed within Jurassic-Cretaceous limestones, and occurs in close spatial association with calcite. The crystals have their cores enriched in Sr and contain abundant monophase (liquid) fluid inclusions of primary and pseudosecondary origin. The barite probably precipitated slowly at a relatively low supersaturation and under the control of a surface reaction precipitation mechanism. However, there were some episodes during its formation with a fast growth rate and the coupled dissolution and recrystallization processes. A combination of fluid inclusion data and stable δ18O value for barite (+ 6.71‰ VSMOW) suggests that low-salinity barite-forming solutions resulted from the mixing of strongly-diluted meteoric waters (enriched in light oxygen isotope) with magmatic-hydrothermal fluids under low-temperature conditions (< 100 °C). Meanwhile, the mineralizing fluids must have been enriched in Ba, Sr, Ca, Mg, and other elements derived from the alteration of carbonate and silicate minerals in sedimentary and igneous rocks. The coupling between sulphur and oxygen isotope data (+ 16.39‰ VCDT and + 6.71‰ VSMOW, respectively) further suggests that barite crystallized in steam-heated environment, where SO42- derived from magmatic-hydrothermal SO2 reacted with sulphates that originate from the oxidation of H2S under near-surface conditions.

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“…Using Ar diffusion modelling, they suggested that the BC in the Lontova Formation was heated to a temperature of 130-140 °C for a duration of 2-5 Myr or the temperature may have been as high as 170 °C during a shorter period of time (< 1 Myr), in relation to largescale fluid migration and dolomitization in the Silurian-early Devonian. Indeed, recent studies (Eensaar et al 2017a(Eensaar et al , 2017bGaškov et al 2017) have shown evidence of hydrothermal activity in the northern BP and have delineated a Zn-Pb mineralization event driven by the intrusion of highly saline low to moderate temperature (60-200 °C) fluids, the maximum age of which can be constrained by crosscutting relationships to the early Middle Devonian (Eifelian). However, this event is tied to thin crosscutting sphalerite-(galena)-calcite veins and scattered fracture zones with no evidence of significant wallrock alteration (Eensaar et al 2017a).…”

Section: Age (Ma)mentioning

confidence: 99%

Illitization of the lower Cambrian (Terreneuvian) Blue Clay in the northern Baltic Palaeobasin

Jõeleht¹,

Kirsimäe²,

Somelar³

2020

EJES

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The clay mineral composition of the lower Cambrian (Terreneuvian) Blue Clay (BC) in the northern Baltic Palaeobasin was studied. The proportion of illite in mixedlayer illitesmectite in the BC increases gradually from ca 85% in northern Estonia to ca 92% in central Latvia with the present burial depth increasing from a few hundred metres to ca 1000 m. The high level of illitization suggests a mature diagenetic grade of the sediments, which is typically achieved with burial at several kilometres. However, uncompact nature and thermally immature organic material suggest only shallow burial and maximum palaeotemperatures not exceeding 50 °C. The smectitetoillite transformation in the BC was described using a kinetic modelling to assess the constraints on burialdriven illitization. Modelling results show that the present illitization level is possible to achieve by assuming burial during the Devonian to Permian prior to the erosion in the Mesozoic. The thickness of eroded sediments in the northern part of the basin was in this case only about 400-800 m. The smectitetoillite transformation process in the BC in the northern Baltic Palaeobasin was controlled rather by time than by temperature.

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Barite mineralization in Kalana speleothems, Central Estonia: Sr, S and O isotope characterization

Cited by 4 publications

References 46 publications

Origin of gem-quality barite at Jebel Ouichane district in Nador, Morocco: implications from integrated fluid inclusions, stable isotopes, and geochemistry

Origin of gem-quality barite at Jebel Ouichane district in Nador, Morocco: implications from integrated fluid inclusions, stable isotopes, and geochemistry

Origin and occurrence of gem-quality, skarn-hosted barite from Jebel Ouichane near Nador in Morocco

Illitization of the lower Cambrian (Terreneuvian) Blue Clay in the northern Baltic Palaeobasin

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