No 5 (2019)

Strontium isotopic composition in waters of mud volcanoes of Azerbaijan
Bujakaite M.I., Lavrushin V.Y., Pokrovsky B.G.

The isotopic composition of strontium was studied in the waters of 22 Azerbaijan mud volcanoes, in which the isotope composition of oxygen and hydrogen, as well as the concentration of macro and micro elements, was previously [Lavrushin et al., 2015] determined. 87Sr/86Sr ratios in the waters of Azerbaijan mud volcanoes are within 0.7067…0.7083. The minimum ratio was established in Neftechala Yuzhnaya volcano, located in the south of the territory ‒ in the Kura region, which is characterized by the lowest average values of 87Sr/86Sr = 0.7070±0.0003 and δ18O = 2.0±1.8‰ compared to volcanoes situated northern ‒ in Shemakha ‒ Gobustan, Absheron and Caspian regions (87Sr/86Sr average = 0.7076±0.0005, δ18O average = 4.8±2.5‰). The relation between the strontium isotopic composition and the isotopic composition of oxygen suggests that the formation of the isotopic characteristics of the mud volcanic waters of Azerbaijan involves two main sources, one of which is predominantly associated with sedimentary carbonates of Cretaceous-Paleogene age, and the second, prevailing in the Kura region, has traces of isotopic exchange with volcanic rocks. The role of strontium dissolved in the sea water, as well as strontium, which could be extracted from modern terrigenous sediments of the Caspian Sea and terrigenous clay rocks of the Maikop series in the mud volcanic waters of Azerbaijan is insignificant.

Литология и полезные ископаемые. 2019;(5):391-403
Disribution of elements in ferrum-manganese nodules in seas and lakes
Baturin G.N.

The element composition of manganese nodules from the inner lakes and arctic seases has beeb studied for comparison with ferrum-manganese nodules from the World ocean which helped to find their similar and different features as well as the trends to accumulate more elements which is related to their ferrum-manganese environment. The correlation coefficients have been calculated for all samples. The high concentration of ferrum-manganese and iron in arctic nodules.

Литология и полезные ископаемые. 2019;(5):404-417
Tectonic-sedimentary system of the Atlantis-meteor seamounts (North Atlantic): late Miocene to Pliocene volcanic and sedimentary environments and the position within the Atlantic-arctic structures
Chamov N.P., Stukalova I.E., Sokolov S.Y., Peyve A.A., Gor’kova N.V., Razumovskiy A.A., Bylinskaya M.E., Golovina L.A.

The article concerns the original materials obtained in the 33-rd cruise of the R/V “Akademik Nikolai Strakhov” in the eastern part of the North Atlantic while studying the system of Atlantis–Meteor seamounts. The system is a single volcanic uplift formed on the Canary Abyssal Plate, and is one of the key objects for understanding the geological history of this segment of the Atlantic Ocean. The article discusses basalts, tefrites, and organogenic-terrigenous lagoon-marine sediments dredged from the Atlantis, Plateau, and Cruiser seamounts. The petrographic properties and compositions of the basalts of the seamounts Atlantis and Cruiser reflect significant differences in the environments of their effusions. In the first case, well-crystallized, not showing signs of vesicularity, olivine basalts poured out in deep-water conditions. Glassy highly vesicular basalts from the Cruiser seamount are characteristic of shallow subaerial effusions. Evidence has been obtained in favor of the subaerial settings of the accumulation of tefrites from the Plato seamount. The regularities of lithogenetic transformations of organogenic-terrigenous deposits of the Cruiser seamount, exposed to high-temperature effects of subaerial lava flows, are revealed. In the course of volcanogenic-sedimentary lithogenesis, the lignite-like material lost its primary structure, turning into natural anisotropic coke with a wide development of fusinite and pyrofusinite. The authors of the article associate the studied volcanic manifestations with the final (Late Miocene–Pliocene) stage of volcanism in the seamount system, which preceded the disintegration of the system, its progressive immersion and the transformation of islands into guyots.

Литология и полезные ископаемые. 2019;(5):418-438
Synrift sandstones and clayey rocks: bulk chemical composition and location on a number of discriminant paleogeodynamic diagrams
Maslov A.V., Podkovyrov V.N., Gareev E.Z., Nozhkin A.D.

The bulk chemical composition of synrift sandstones and associated clayey rocks has been analized, and the distribution of the fields they form has been studied on discriminant paleogeodynamic SiO2–K2O/Na2O [Roser, Korsch, 1986] and DF1–DF2 [Verma, Armstrong-Altrin, 2013] diagrams. The studied sandstones in terms of bulk chemical composition mainly correspond to greywacke, lititic, arkose and subarkose psammites; Sublitites and quartz arenites are also found. A significant part in the analyzed data massif consists of psammites, in which log(Na2O/K2O)<-1.0; missing on the Pettijohn classification chart. This confirms our conclusion, based on the results of mineralogical and petrographic studies, that the sedimentary infill of rift structures unites immature sandstones, the detrital framework of which was formed due to erosion of local sources, represented by various magmatic and sedimentary formations. Synrift clayey rocks, compared with sandstones, are composed of more mature fine-grained siliciclastics. As follows from the distribution of figurative data points of clayey rocks on the F1–F2 diagram [Roser, Korsch, 1988], its sources were mainly sedimentary deposits. The content of most of the main rock-forming oxides in the synrift sandstones is almost the same as in silt-sandstone rocks present in the Upper Precambrian-Phanerozoic sedimentary mega-complex of the East European Plate, but at the same time differs significantly from the Proterozoic and Phanerozoic cratonic sediments, as well as from the average composition upper continental crust. It is shown that the distribution of the fields of syntift sandstones and clayey rocks on the SiO2–K2O/Na2O diagram does not have any distinct features, and their figurative data points are localized in the areas of terrigenous rocks of passive and active continental margins. On the DF1–DF2 diagram, the fields of the studied psammites and clayey rocks are located in areas of riftogenous and collisional environments. We have proposed a different position of the border between these areas in the diagram, which will require further verification.

Литология и полезные ископаемые. 2019;(5):439-465
Rare elements — setting markers of the formation of the manganese and iron ore deposits of Kalahari and Postmasburg areas (South Africa). Communication 2. Iron- and manganese ore of Postmasburg area
Varentsov I.M., Kuleshov V.N.

In the world resources of manganese and iron ores, a significant place belongs to the Postmasburg ore field (South Africa), enclosed in rocks of the Transvaal Supegroup. Ore deposits have the nature of karst residual accumulations. A number of elements (B, Cr, Ni, Zn, Ge, As, Se, Mo, Ag, Cd, Sb, Te, W, Pb, REE) form a characteristic association that sheds light on the geochemistry of the ore formation processes. Of these, the most representative elements are: Mo, As, Ag and REE. Molybdenum is distinguished by the chemisorption incorporation nature of accumulation in the ores under consideration, often with the formation of epic growths of ferri molybdate-type minerals. Arsenic leached from substrate rocks and accumulated in karstic Mn-Fe- and Fe-ores reflects the total effect of the dominant iron oxide minerals on its mobility. The behavior of silver is controlled by the processes of hypergenic change of Archean-Early Proterozoic carbonate rocks and banded iron ores (BIF). Comparison of the distribution of REE in karst Fe-, Mn-Fe- and Mn-ores and in banded iron ores shows that they are characterized by similar values of cerium (C/Ce*) and europium (Eu/Eu*) anomalies, but differ in the fractionation of heavy and light REE (typical values: Ce/Ce* = 0.7‒1.0; Eu/Eu* = 0.8‒1.1). Strip iron ores and associated manganese ore deposits accumulated in the marginal anoxide-disoxide marine basin, which was limited to continental land. Anoxide and disoxide conditions were the result of intense hydrothermal activity.

Литология и полезные ископаемые. 2019;(5):466-485
Age mark of holocen soil formation of Moscow region′s (upper Klyazma basin)
Pevzner M.M., Petrov O.L., Nechushkin R.I., Karimov T.D., Bolshakova V.V.

Radiocarbon studies of three pits in the upper Klyazma river basin near the village of Chashnikovo were carried out to determine the age of buried peat and soils. On the basis of nine radiocarbon dates, the age mark of the beginning of waterlogging on the watershed hill (1650 or 1790 years AD), the termination of the activity of the hydrocarbonate source and the beginning of soil formation in the rear of the high floodplain (about 300 years BC), as well as the age of water drain/drainage of the glacial lake and the beginning of peat accumulation (about 9.3 thousand years BC) in the upper Klyazma valley were determined. The isotopic composition (δ18О, δ13C) and Genesis of travertine-like carbonates, the deposition of which is presumably associated with the activity of the hydrocarbonate source, were determined.

Литология и полезные ископаемые. 2019;(5):486-494

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