Dolomitic calcretes from the Changhsignian (Upper Permian) red beds of the Orenburg Cis-Urals, Russia
The dolomitic calcrete profiles from the Boyevaya Gora and Tuyembetka sections, both represented by the uppermost Permian (Changhsignian) red continental deposits from the Orenburg Cis-Urals, were studied by sedimentological, mineralogical, and geochemical methods. Сalcrete from the Boyevaya Gora s...
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Kazan Federal University
2021-09-01
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| Series: | Учёные записки Казанского университета: Серия Естественные науки |
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| Online Access: | https://kpfu.ru/uz-eng-ns-2021-3-4.html |
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| author | F.A. Mouraviev N.M. Khasanova E.Z. Yunusova |
| author_facet | F.A. Mouraviev N.M. Khasanova E.Z. Yunusova |
| author_sort | F.A. Mouraviev |
| collection | DOAJ |
| description | The dolomitic calcrete profiles from the Boyevaya Gora and Tuyembetka sections, both represented by the uppermost Permian (Changhsignian) red continental deposits from the Orenburg Cis-Urals, were studied by sedimentological, mineralogical, and geochemical methods.
Сalcrete from the Boyevaya Gora section formed on sandy-silty flat alluvial fan/sheetflood sediments, under the setting of slow subsidence of the territory. Calcrete from the Tuyembetka section developed on relatively elevated mudflat/playa under a stable tectonic regime.
The subtropical semi-arid climate was reconstructed based on the geochemical indices from the illuvial paleosol horizons. The presence of anhydrite in the calcrete profiles indicates the saline conditions of soil waters. Cryprocrystalline idiomorphic grains (1–3 μm) and the low Mn2+ partitioning ratio between the Ca- and Mg-position in dolomite (0.7–1.8) suggest its primary origin and a rapid crystallization from the soil waters. Free organic radicals and phosphorus-associated anion centers in the pedogenic dolomite identified by the electron paramagnetic resonance (EPR) analysis assume a biogenic contribution to the formation of dolomite.
Fossilized fungal hyphae and bacteriomorphs along with the fragments of plant roots were detected by scanning electron microscopy (SEM) in both calcretes. The bacterial origin of dolomite from the studied calcretes was discussed. |
| format | Article |
| id | doaj-art-4a6afbcef78b4c0ea6740072b0e78c74 |
| institution | DOAJ |
| issn | 2542-064X 2500-218X |
| language | English |
| publishDate | 2021-09-01 |
| publisher | Kazan Federal University |
| record_format | Article |
| series | Учёные записки Казанского университета: Серия Естественные науки |
| spelling | doaj-art-4a6afbcef78b4c0ea6740072b0e78c742025-08-20T02:58:30ZengKazan Federal UniversityУчёные записки Казанского университета: Серия Естественные науки2542-064X2500-218X2021-09-01163337138910.26907/2542-064X.2021.3.371-389Dolomitic calcretes from the Changhsignian (Upper Permian) red beds of the Orenburg Cis-Urals, RussiaF.A. Mouraviev0N.M. Khasanova1E.Z. Yunusova2Kazan Federal University, Kazan, 420008 RussiaKazan Federal University, Kazan, 420008 Russia“Spectrum” Engineering Сompany, Kazan, 420061 RussiaThe dolomitic calcrete profiles from the Boyevaya Gora and Tuyembetka sections, both represented by the uppermost Permian (Changhsignian) red continental deposits from the Orenburg Cis-Urals, were studied by sedimentological, mineralogical, and geochemical methods. Сalcrete from the Boyevaya Gora section formed on sandy-silty flat alluvial fan/sheetflood sediments, under the setting of slow subsidence of the territory. Calcrete from the Tuyembetka section developed on relatively elevated mudflat/playa under a stable tectonic regime. The subtropical semi-arid climate was reconstructed based on the geochemical indices from the illuvial paleosol horizons. The presence of anhydrite in the calcrete profiles indicates the saline conditions of soil waters. Cryprocrystalline idiomorphic grains (1–3 μm) and the low Mn2+ partitioning ratio between the Ca- and Mg-position in dolomite (0.7–1.8) suggest its primary origin and a rapid crystallization from the soil waters. Free organic radicals and phosphorus-associated anion centers in the pedogenic dolomite identified by the electron paramagnetic resonance (EPR) analysis assume a biogenic contribution to the formation of dolomite. Fossilized fungal hyphae and bacteriomorphs along with the fragments of plant roots were detected by scanning electron microscopy (SEM) in both calcretes. The bacterial origin of dolomite from the studied calcretes was discussed.https://kpfu.ru/uz-eng-ns-2021-3-4.htmlcalcretedolomiteparamagnetic centersbioturbationpaleosolvyatkian stagepermianorenburg cis-urals |
| spellingShingle | F.A. Mouraviev N.M. Khasanova E.Z. Yunusova Dolomitic calcretes from the Changhsignian (Upper Permian) red beds of the Orenburg Cis-Urals, Russia Учёные записки Казанского университета: Серия Естественные науки calcrete dolomite paramagnetic centers bioturbation paleosol vyatkian stage permian orenburg cis-urals |
| title | Dolomitic calcretes from the Changhsignian (Upper Permian) red beds of the Orenburg Cis-Urals, Russia |
| title_full | Dolomitic calcretes from the Changhsignian (Upper Permian) red beds of the Orenburg Cis-Urals, Russia |
| title_fullStr | Dolomitic calcretes from the Changhsignian (Upper Permian) red beds of the Orenburg Cis-Urals, Russia |
| title_full_unstemmed | Dolomitic calcretes from the Changhsignian (Upper Permian) red beds of the Orenburg Cis-Urals, Russia |
| title_short | Dolomitic calcretes from the Changhsignian (Upper Permian) red beds of the Orenburg Cis-Urals, Russia |
| title_sort | dolomitic calcretes from the changhsignian upper permian red beds of the orenburg cis urals russia |
| topic | calcrete dolomite paramagnetic centers bioturbation paleosol vyatkian stage permian orenburg cis-urals |
| url | https://kpfu.ru/uz-eng-ns-2021-3-4.html |
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