First find of kutnohorite in modern sediments of the South Caspian basin

Dara, O. M.; Lein, Alla Yu; Kozina, N. V.; Ivanov, Mark V.

doi:10.1134/s1028334x15120089

Cited by 6 publications

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“…A distinctive feature of studied sediments is high contents of authigenic sulfate and carbonate minerals, such as gypsum (up to 25%), calcite (up to 8%), magnesian calcite (up to 11%), kutnahorite (up to 6%) [Dara et al, 2015;Kozina, 2017]. High concentration of halite has been recorded at the top of the column (16% in the interval 0-0.5 cm).…”

Section: Resultsmentioning

confidence: 92%

Framboidal pyrite formation in the bottom sediments of the South Caspian Basin under conditions of hydrogen sulfide contamination

Kozina¹,

Reykhard²,

Dara³

et al. 2018

Russ. J. Earth Sci.

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Structural features and distribution of framboidal pyrite were studied during lithological, mineralogical and geochemical studies of sediments in the South Caspian Basin. The lithological and geochemical parameters affecting the intensity of the formation of authigenic pyrite in sediments of the South Caspian Basin under conditions of hydrogen sulfide contamination were determined. According to X-ray diffraction (XRD), the content of pyrite in pelitic ooze reaches 4%. Microscopic studies have shown that pyrite formation occurs intensively in sediments with a high content of biogenic mineral components, such as opal diatom frustules and calcite plates of coccolithophores. Scanning electron microscopy (SEM) has demonstrated the presence of spherical pyrite framboids, as well as individual pyrite crystallites and their disordered clusters of various shapes. The diameter of the framboids varies from 3 to 10 microns. Pyrite crystallites have subspherical, complicated polyhedral, prismatic, octahedral, pentagonal dodekahedron shapes. The crystallite sizes range from 0.5 to 3 microns. Based on geochemical data, there is no direct correlation between the intensity of pyrite formation and the high content of such components as Fe and C org in bottom sediments. We assume that the formation of authigenic framboid pyrite in surface sediments (including the fluffy layer) is most likely due to the presence of hydrogen sulfide contamination in the near bottom water of the South Caspian Basin. Framboidal pyrite in the deeper layers (up to a depth of 35 cm) is the result of diagenetic processes that occur in accordance with the classical scheme of vertical zonality of diagenetic transformations in sediments.

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Section: Resultsmentioning

confidence: 92%

Framboidal pyrite formation in the bottom sediments of the South Caspian Basin under conditions of hydrogen sulfide contamination

Kozina¹,

Reykhard²,

Dara³

et al. 2018

Russ. J. Earth Sci.

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“…Kutnohorite was detected in the uppermost layer of the sediment (0.0-3.0 cm), where its content varies from 2 to 6%, reaching a maximum in the layer of 0.5-1.0 cm (Table 1). Kutnohorite is represented by numerous clusters of irregularly shaped microcrystal aggregates (Figure 4j) [8,9,44].…”

Section: Lithological Mineralogical and Geochemical Characteristics Of The South Caspian Basinmentioning

confidence: 99%

“…Kutnohorite is found only in the surface layer of bottom sediments of the South Caspian Basin (0.0-3.0 cm) and should be attributed to authigenic minerals in the early stage of diagenesis. Pore water supersaturated with Ca 2+ and Mn 2+ may be the source of these cations; carbon dioxide, which is a part of kutnohorite, is formed during microbial decomposition of organic matter in sediments [44]. Manganese ores, which are widespread within the Greater Caucasus, and the waters of the Cheleken-Boyadag hydrothermal system enriched in manganese, may also supply Mn to the South Caspian Basin [33,34,44].…”

Section: Authigenic Minerals and Features Of Their Formation In The Bottom Sediments Of The Derbent Basin And The South Caspian Basinmentioning

confidence: 99%

“…The role of clusters, including fine-grained ones, coming from the mountain structures of the Caucasus and the Elburs, is already very small near the coasts, which is largely determined by both the influence of the marginal filter and the large-scale current cycles existing in the Caspian Sea [42,43]. As a result, the mineral composition of surface bottom sediments has already been described [8,9,[44][45][46]. In the works of Kozina [8,9,[44][45][46], the mineral composition of heavy and light subfractions of modern bottom sediments of the Caspian Sea have been studied.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, the mineral composition of surface bottom sediments has already been described [8,9,[44][45][46]. In the works of Kozina [8,9,[44][45][46], the mineral composition of heavy and light subfractions of modern bottom sediments of the Caspian Sea have been studied. Terrigenous-mineralogical provinces have been identified.…”

Section: Introductionmentioning

confidence: 99%

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Authigenic Minerals of the Derbent and South Caspian Basins (Caspian Sea): Features of Forms, Distribution and Genesis under Conditions of Hydrogen Sulfide Contamination

2022

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This paper presents the results of complex lithological, mineralogical, and geochemical studies of bottom sediments of deep-water basins of the Caspian Sea (Derbent and South Caspian Basins) in areas contaminated by hydrogen sulfide. In the course of complex studies, numerous manifestations of authigenic mineral formation associated with the stage of early diagenesis have been established. Authigenic minerals belonging to the groups of sulfates (gypsum, barite), chlorides (halite), carbonates (calcite, low Mg-calcite; kutnohorite), and sulfides (framboidal pyrite), as well as their forms and composition, have been identified by a complex of analytical methods (X-ray diffractometry (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS); atomic absorption spectroscopy (AAS); coulometric titration (CT)); the nature of their distribution in bottom sediments has been assessed. Carbonates and sulfates are predominant authigenic minerals in the deep-water basins of the Caspian Sea. As a part of the study, differences have been established in the composition and distribution of associations of authigenic minerals in the bottom sediments in the deep-water basins. These are mineral associations characteristic of the uppermost part of the sediments (interval 0–3 cm) and underlying sediments. In the Derbent Basin, in sediments of the interval 3–46 cm, an authigenic association is formed from gypsum, calcite, magnesian calcite, siderite, and framboidal pyrite. An association of such authigenic minerals as gypsum and calcite is formed in sediments of the 0–3 cm interval. In the South Caspian Basin, in sediments of the interval 3–35 cm, an association of such authigenic minerals as gypsum, halite, calcite, magnesian calcite, and framboidal pyrite is formed. The association of such authigenic minerals as gypsum, halite, calcite, magnesian calcite, kutnohorite, and framboidal pyrite is characteristic of sediments of the 0–3 cm interval. We consider the aridity of the climate in the South Caspian region to be the main factor that determines the appearance of such differences in the uppermost layer of sediments of the basins. Judging by the change in the composition of authigenic associations, the aridity of the South Caspian increased sharply by the time of the accumulation of the upper layer of sediments (interval 0–3 cm). Taking into account lithological, mineralogical and geochemical data, the features of the processes of authigenic mineral formation in the deep-water basins of the Caspian Sea under conditions of hydrogen sulfide contamination have been determined. Analysis of the results obtained and published data on the conditions of sedimentation in the Caspian Sea showed that hydrogen sulfide contamination recorded in the bottom layer of the water column of the deep-water basins of the Caspian Sea may affect the formation of authigenic sulfides (framboidal pyrite), sulfates (gypsum), and carbonates (calcite and kutnohorite) associated with the activity of sulfate-reducing bacteria in reducing conditions.

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Characteristic Property of the Formation of Authigenic Minerals in Bottom Sediments of the South Caspian Basin under Hydrogen Sulfide Contamination Conditions

et al. 2021

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First find of kutnohorite in modern sediments of the South Caspian basin

Cited by 6 publications

References 3 publications

Framboidal pyrite formation in the bottom sediments of the South Caspian Basin under conditions of hydrogen sulfide contamination

Framboidal pyrite formation in the bottom sediments of the South Caspian Basin under conditions of hydrogen sulfide contamination

Authigenic Minerals of the Derbent and South Caspian Basins (Caspian Sea): Features of Forms, Distribution and Genesis under Conditions of Hydrogen Sulfide Contamination

Characteristic Property of the Formation of Authigenic Minerals in Bottom Sediments of the South Caspian Basin under Hydrogen Sulfide Contamination Conditions

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