Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals)
The Shatak Formation, comprising a part of the Mashak Suite (RF<sub>2</sub>), is located on the western slope of the Southern Urals. It consists of various rock types, including sedimentary rocks, such as conglomerates, polymictic sandstones, aleurolites, and carbonaceous clayey shales,...
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MDPI AG
2023-07-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/13/7/935 |
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| author | Sergey G. Kovalev Sergey S. Kovalev Aysylu A. Sharipova |
| author_facet | Sergey G. Kovalev Sergey S. Kovalev Aysylu A. Sharipova |
| author_sort | Sergey G. Kovalev |
| collection | DOAJ |
| description | The Shatak Formation, comprising a part of the Mashak Suite (RF<sub>2</sub>), is located on the western slope of the Southern Urals. It consists of various rock types, including sedimentary rocks, such as conglomerates, polymictic sandstones, aleurolites, and carbonaceous clayey shales, as well as igneous rocks, including picrites, basalts, dacites, rhyodacites, and rhyolites, and volcanogenic–sedimentary rocks, such as tuffs and tuff breccias. In this article, oxyfluoride (La, Ce) (O<sub>n</sub>F<sub>m</sub>)<sub>3</sub> mineralization, occurring in the contact zone between the metabasalts and quartz sandstones, is described for the first time in the literature. This is represented by compounds of variable compositions forming an isomorphic series: trifluoride, (La, Ce)F<sub>3</sub>–oxyfluoride, (La, Ce)OF–oxide, and (La, Ce)<sub>2</sub>O<sub>3</sub>. By analyzing several binary phase diagrams, significant coordination between oxygen, fluorine, and cerium in the chemical composition of oxyfluorides has been highlighted. However, the behavior of lanthanum has been shown to exhibit some irregularity. The genesis of oxyfluoride mineralization is attributed to the regional metamorphism of rocks within the Shatak Formation. During the hydrothermal process, the decomposition of fluorapatite, which is unstable during both hydrothermal metamorphism and supergene processes, resulted in the release of fluorine, as well as potentially lanthanum and cerium. Variations in the chemical composition of oxyfluorides, which are formed in the presence of an excess of oxygen resulting from water dissociation, are determined by local differences in the content of the main components within the forming microfractures. |
| first_indexed | 2024-03-11T00:47:53Z |
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| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-11T00:47:53Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-6186f612468d4be296bd0d1b2d7f55b62023-11-18T20:39:06ZengMDPI AGMinerals2075-163X2023-07-0113793510.3390/min13070935Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals)Sergey G. Kovalev0Sergey S. Kovalev1Aysylu A. Sharipova2Institute of Geology, Ufa Federal Research Centre, Russian Academy of Sciences, Karl Marx Street, 16/2, 450077 Ufa, RussiaInstitute of Geology, Ufa Federal Research Centre, Russian Academy of Sciences, Karl Marx Street, 16/2, 450077 Ufa, RussiaInstitute of Geology, Ufa Federal Research Centre, Russian Academy of Sciences, Karl Marx Street, 16/2, 450077 Ufa, RussiaThe Shatak Formation, comprising a part of the Mashak Suite (RF<sub>2</sub>), is located on the western slope of the Southern Urals. It consists of various rock types, including sedimentary rocks, such as conglomerates, polymictic sandstones, aleurolites, and carbonaceous clayey shales, as well as igneous rocks, including picrites, basalts, dacites, rhyodacites, and rhyolites, and volcanogenic–sedimentary rocks, such as tuffs and tuff breccias. In this article, oxyfluoride (La, Ce) (O<sub>n</sub>F<sub>m</sub>)<sub>3</sub> mineralization, occurring in the contact zone between the metabasalts and quartz sandstones, is described for the first time in the literature. This is represented by compounds of variable compositions forming an isomorphic series: trifluoride, (La, Ce)F<sub>3</sub>–oxyfluoride, (La, Ce)OF–oxide, and (La, Ce)<sub>2</sub>O<sub>3</sub>. By analyzing several binary phase diagrams, significant coordination between oxygen, fluorine, and cerium in the chemical composition of oxyfluorides has been highlighted. However, the behavior of lanthanum has been shown to exhibit some irregularity. The genesis of oxyfluoride mineralization is attributed to the regional metamorphism of rocks within the Shatak Formation. During the hydrothermal process, the decomposition of fluorapatite, which is unstable during both hydrothermal metamorphism and supergene processes, resulted in the release of fluorine, as well as potentially lanthanum and cerium. Variations in the chemical composition of oxyfluorides, which are formed in the presence of an excess of oxygen resulting from water dissociation, are determined by local differences in the content of the main components within the forming microfractures.https://www.mdpi.com/2075-163X/13/7/935Southern UralsShatak Formationregional metamorphismrare-earth elementsoxyfluorides |
| spellingShingle | Sergey G. Kovalev Sergey S. Kovalev Aysylu A. Sharipova Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals) Minerals Southern Urals Shatak Formation regional metamorphism rare-earth elements oxyfluorides |
| title | Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals) |
| title_full | Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals) |
| title_fullStr | Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals) |
| title_full_unstemmed | Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals) |
| title_short | Oxyfluorides of Rare-Earth Elements in the Rocks of the Shatak Formation (Southern Urals) |
| title_sort | oxyfluorides of rare earth elements in the rocks of the shatak formation southern urals |
| topic | Southern Urals Shatak Formation regional metamorphism rare-earth elements oxyfluorides |
| url | https://www.mdpi.com/2075-163X/13/7/935 |
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