Multidisciplinary studies of the caspian sea system during cruise 39 of the R/V Rift

Ambrosimov, A. K.; Klyuvitkin, А. А.; Goldin, Yu. A.; Zakharova, E. E.; Корж, А. О.; Кравчишина, М. Д.; Mutovkin, A. D.; Novigatsky, А. N.; Politova, N. V.; Savvichev, Alexander S; Chul’tsova, A. L.

doi:10.1134/s0001437014020015

Cited by 8 publications

(6 citation statements)

References 3 publications

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“…The studied material was sampled during the 39th cruise of the R/V Rift in 2012 within the framework of the project "The Caspian Sea System" under the guidance of Academician A. P. Lisitzin [Ambrosimov et al, 2014;.…”

Section: Methodsmentioning

confidence: 99%

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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: Methodsmentioning

confidence: 99%

“…It is important to note that since 1930 the unstable presence of hydrogen sulfide was recorded in bottom waters in the Southern Caspian [Ambrosimov et al, 2014;Ivanov et al, 2013;Sapozhnikov et al, 2007]. The first data on the presence of small concentration of hydrogen sulfide were recorded in 1933-1934[Bruevich, 1937.…”

Section: Es6003mentioning

confidence: 99%

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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“…In the last few years, the researchers of the P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, have performed multidisciplinary research of oceanological, geological, and biochemical processes in the Caspian Sea [27][28][29][30][31][32]. As a result, new data on the distribution of sedimentary matter flows in the water column have been described [33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

“…Regard must be paid to the presence of hydrogen sulfide recorded in the near-bottom waters of the Derbent and South Caspian Basins since the 1930s [28,37,47]. This phenomenon was observed alongside significant fluctuations in sea level, recorded since the 1950s [48] and is associated with both climatic changes and anthropogenic factors [37].…”

Section: Introductionmentioning

confidence: 99%

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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“…Despite the importance of this sea region for the general circulation of the Caspian, the dynamics of the waters in it have not been sufficiently studied. In the works [1,2] analyzing the data on measurements of current profiles, it is pointed out that there are currents of opposite directions in the west and east: part of the waters of the Middle Caspian cyclonic circulation turns south, crossing the sill in its western part, while in the east the inflow of relatively heavy waters of the South Caspian to the Middle Caspian occurs [3]. At the same time, twice as high velocities are observed in the west than in the east.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the Caspian Sea Waters over the Apsheron Sill in 2003

Dyakonov¹,

Ibrayev²

2019

PhO

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The paper is aimed at studying water exchange between the Middle and South Caspian, at assessing its intensity, spatial-temporal structure and variability. Methods and Results. The study includes the numerical model of the Caspian Sea general circulation; it is of sufficiently high resolution for reproducing mesoscale structure of the currents-2 km. Due to the model, the Caspian Sea circulation in 2003 was reconstructed and the basic characteristics of water transfer between the Middle and the South Caspian were calculated. This specific year was chosen since in all its months, the wind fields in the Middle and South Caspian water areas were in good agreement with the average climatic ones. The simulated structure of the currents over the Apsheron Sill represents the following pattern: the northward currents are most often formed over the eastern shelf slopes, and the southward ones-over the western shelf slope. The latter are usually more intense and regular. From mid-July to October, the easterly winds regularly occur over the Caspian Sea strengthening the northward currents, which, in their turn, transfer relatively salty and warm South Caspian waters to the Middle Caspian along the eastern coast. A fairly stable southward stream resulted from the density gradient between the cold Middle and the warm South Caspian, is located along the western shelf slope at the depths 100-150 m. On the whole, the water flow above the sill is directed from north to south. At that the southward flows are distributed rather evenly throughout the year, whereas the major part of the northward currents' flow is observed from late July to December. Conclusions. Since the South Caspian waters on all the depths are warmer and more salty than those in the Middle, water exchange between the two basins in course of the whole year, contributes to increase both of temperature and salinity in the Middle Caspian, and to their decrease in the South Caspian. The current-originated salt flows in the region are sufficient to make salinity grow in the Middle Caspian upper layer by 0.5 psu within 100 days, at that the corresponding temperature increase does not exceed 0.01-0.03 °C per day. The reverse southward currents transfer relatively fresh water to the South Caspian that lowers salinity of its upper layer by 0.2 psu per month. However, such intense intrusions are noted only in March and December. The impact of these currents on the South Caspian heat balance is more uniform throughout the year and does not exceed 0.17 °C/day.

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Multidisciplinary studies of the caspian sea system during cruise 39 of the R/V Rift

Cited by 8 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

Dynamics of the Caspian Sea Waters over the Apsheron Sill in 2003

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