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

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 87
Author(s):  
Nina Kozina ◽  
Liudmila Reykhard ◽  
Olga Dara
Keyword(s):  
Hydrogen Sulfide ◽  
Bottom Sediments ◽  
Deep Water ◽  
Caspian Sea ◽  
The South ◽  
The Caspian Sea ◽  
Authigenic Minerals ◽  
Framboidal Pyrite ◽  
Magnesian Calcite ◽  
Authigenic Mineral

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.

scholarly journals Numerical modelling of the Caspian Sea tides

Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 209-219
Author(s):  
Igor P. Medvedev ◽  
Evgueni A. Kulikov ◽  
Isaac V. Fine
Keyword(s):  
Caspian Sea ◽  
Ocean Model ◽  
Tidal Range ◽  
The South ◽  
Tidal Dynamics ◽  
The Caspian Sea ◽  
Sea Levels ◽  
The North ◽  
Anticlockwise Rotation ◽  
Diurnal Tides

Abstract. The Caspian Sea is the largest enclosed basin on Earth and a unique subject for the analysis of tidal dynamics. Tides in the basin are produced directly by the tide-generating forces. Using the Princeton Ocean Model (POM), we examine details of the spatial and temporal features of the tidal dynamics in the Caspian Sea. We present tidal charts of the amplitudes and phase lags of the major tidal constituents, together with maps of the form factor, tidal range, and tidal current speed. Semi-diurnal tides in the Caspian Sea are determined by a Taylor amphidromic system with anticlockwise rotation. The largest M2 amplitude is 6 cm and is located in Türkmen Aylagy (called Turkmen Bay hereafter). For the diurnal constituents, the Absheron Peninsula separates two individual amphidromes with anticlockwise rotation in the north and in the south. The maximum K1 amplitudes (up to 0.7–0.8 cm) are located in (1) the south-eastern part of the basin, (2) Türkmenbaşy Gulf, (3) Mangyshlak Bay; and (4) Kizlyar Bay. As a result, the semi-diurnal tides prevail over diurnal tides in the Caspian Sea. The maximum tidal range, of up to 21 cm, has been found in Turkmen Bay. The strongest tidal currents have been located in the straits to the north and south of Ogurja Ada, where speeds reach 22 and 19 cm s−1, respectively. Numerical simulations of the tides using different mean sea levels (within a range of 5 m) indicate that spatial features of the Caspian Sea tides are strongly sensitive to changes in mean sea level.

REE systematics in modern bottom sediments of the Caspian Sea and river deltas worldwide: Experience of comparison

2017 ◽  
Vol 475 (1) ◽  
pp. 797-802
Author(s):  
A. V. Maslov ◽  
N. V. Kozina ◽  
V. P. Shevchenko ◽  
A. A. Klyuvitkin ◽  
Ph. V. Sapozhnikov ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
River Deltas

The Cadusii in Archaeology? Remarks on the Achaemenid Period (Iron Age IV) in Gilan and Talesh

2013 ◽  
Vol 17 (2) ◽  
pp. 115-151
Author(s):  
Christian Konrad Piller
Keyword(s):  
Material Culture ◽  
Iron Age ◽  
Caspian Sea ◽  
Point Of View ◽  
Armed Conflicts ◽  
The South ◽  
The Caspian Sea ◽  
Material Basis ◽  
South West ◽  
New Material

According to some classical authors, the region south-west of the Caspian Sea was inhabited by the large tribe of the Cadusians (Greek Καδουσιοι, Latin Cadusii). During the Achaemenid Period, several armed conflicts between the Imperial Persian forces and the warlike Cadusians occurred. Of particular importance is the disastrous defeat of Artaxerxes II in 380 B.C. From the archaeological point of view, little has been known about the material culture of the Achaemenid Period (Iron Age IV) in Talesh and Gilan. Until recently, only a few burial contexts from the South of Gilan could be dated to the period between the 6th and 4th centuries B.C. However, during the last two decades, Iranian archaeologists excavated numerous Bronze and Iron Age graveyards in the Talesh Region. A number of burial contexts at sites, such as Maryan, Mianroud or Vaske can securely be dated to the Achaemenid Period. With this new material basis, it was possible to subdivide the Iron Age IV into different subsequent phases. Furthermore, it is likely that the material culture described in this article could be at least partially attributed to the Cadusians.

scholarly journals Current State of Heterotrophic Bacterioplankton and Bacteriobenthos in the Northern and Middle Parts of the Caspian Sea

2020 ◽  
Author(s):  
Svetlana Dyakova ◽  
Victoria Volodina ◽  
Ekaterina Galyautdinova ◽  
Anna Menkova ◽  
Olga Soprunova
Keyword(s):  
Species Composition ◽  
Crude Oil ◽  
Bottom Sediments ◽  
Caspian Sea ◽  
Heterotrophic Bacteria ◽  
Middle Part ◽  
The Caspian Sea ◽  
Heterotrophic Bacterioplankton ◽  
Fermenting Bacteria ◽  
Two Peaks

Data on the abundance of heterotrophic bacterioplankton and bacteriobenthos in the northern and middle parts of the Caspian during the period from 2013 to 2017 are presented. In the waters of the northern part of the Caspian, a peak in the number of saprotrophs and crude oil degraders was recorded in 2013. In the middle part of the Caspian and in the region of the Mangyshlak regression, high numbers of heterotrophic bacteria were recorded in 2013 and 2016. The biodiversity of bacterioplankton in the surveyed areas is almost the same; the species composition of saprotrophs and crude oil degraders is identical. In the bottom sediments of the northern and middle parts of the Caspian Sea, two peaks of saprotrophic bacteriobenthos development (in 2013 and 2016) were recorded; in the region of the Mangyshlak threshold, the concentration of saprotrophs remained stable. The number of crude oil degraders was inferior to those of saprotrophs, while the proportion of crude oil degraders to saprotrophs changed annually. The species composition of saprotrophs is relatively stable, the biodiversity of oil-oxidizing bacteriobenthos has changed in the direction of increasing the proportion of non-fermenting bacteria. Constant changes in the ratio of the number of saprotrophs and crude oil degraders, together with the transformations of the dominant groups of the species composition of bacteria, indicated the instability of bacteriobenthos, and, as a result, the vulnerability of the microecosystem of bottom sediments under changing environmental conditions.

Distribution of some rare and trace elements in modern bottom sediments of the Caspian Sea

Oceanology ◽  
2016 ◽  
Vol 56 (4) ◽  
pp. 552-563 ◽  
Author(s):  
A. V. Maslov ◽  
N. V. Kozina ◽  
A. A. Klyuvitkin ◽  
A. N. Novigatsky ◽  
A. S. Filippov ◽  
...  
Keyword(s):  
Trace Elements ◽  
Bottom Sediments ◽  
Caspian Sea ◽  
The Caspian Sea

Hydrochemical Studies of Deep-Water Basins of the Caspian Sea in August–September 2013 Onboard the R/V “Nikifor Shurekov”

2015 ◽  
Vol 55 (1) ◽  
pp. 162-164
Author(s):  
L. A. Dukhova ◽  
E. A. Serebrennikova ◽  
A. K. Ambrosimov ◽  
A. A. Klyuvitkin
Keyword(s):  
Deep Water ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
Hydrochemical Studies
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