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Vol 52, No 4 (2017)
- Year: 2017
- Articles: 7
- URL: https://journals.rcsi.science/0024-4902/issue/view/9863
Article
Composition of interstitial waters and forms of sulfur compounds in bottom sediments in the northeastern Black Sea
Abstract
Study of sediments and water column in the Black Sea has been carried out for a long time. However, issues of the formation of seawater and sediments in the geological (ancient) and Recent marine history remain debatable so far. Studies of the physical, biological, and biogeochemical settings in the northeastern part of the Black Sea carried out onboard the R/V Professor Shtokman in 2009 yielded new data on this region. The present paper reports the results of study of the chemical composition of bottom sediments and interstitial waters from the meridional profile extending from the Kerch Peninsula to the central part of the eastern deep-water depression.
249-262
Distribution of rare earth elements in waters and bottom sediments of mineralized lakes in the eastern Transbaikal region (Russia)
Abstract
Contents of rare earth elements in waters and bottom sediments are maximum in the most mineralized soda lakes. It is shown that REE occur in waters mainly as carbonate (LnСО3)+ and oxyhydroxide LnO2H, LnO+, (LnO2)– complexes, whose activity in the La → Lu series changes in opposite directions. It has been determined that increase of mineralization leads mainly to higher concentrations of the dissolved HREE. Prevalence of the absolute values of MREE and HREE is recorded in basins with the development of bacterial processes. Geochemical barrier for the accumulation of LREE in waters can be represented by fluorcarbonates, whose saturation degree in the soda lake waters can be several orders of magnitude higher than the solubility products (SP). Oxidative and reductive settings in lakes are favorable for the formation of Ce(OH)4 and Ce(OH)3, respectively.
263-277
Structure and petroleum potential of the Laptev Sea region
Abstract
Analysis of specific features of the structure and petroleum potential of the Aptian Laptev Sea region is presented. Age and lithological composition of the sedimentary cover of the shelf are predicted. Oil- and-gas source sequences, catagenetic zonation of organic matter, and potential petroliferous objects in large structural zones are characterized. It is supposed that oil likely played a significant role in the phase composition of naphtides. Its formation in the land and coastal shelf zone was stipulated by the presence of high-quality oil source rocks in the Riphean–Phanerozoic cover of the Siberian Craton. In the remaining part of the shelf, where the Aptian–Cenozoic rift system is widespread, oil can also be present in pools, because the rocks likely accommodate not only gas source rocks, but also deltaic and prodeltaic oil-and-gas source rocks that are located in the main oil formation zone. The above properties are specific features of the study region, and its hydrocarbon potential will be increasing steadily with the shelf development.
278-294
Glauconitic bryozoan shells in shelf sediments of Western Kamchatka
Abstract
Glauconite segregations in Oligocene–Miocene shelf sediments of Western Kamchatka (Kakert and Gakkha horizons) are studied. Glauconite occurs in the studied samples as morphologically different grains, finely dispersed cement, and pseudomorphoses after organogenic structures (siliceous sponge spicules, diatom algae frustules, and others). In addition, samples of the clasts of bryozoans, volcanic glass, and terrigenous grains revealed for the first time traces of the boring algae similar to recent species of genus Hyella and, possibly, Dalmatella, whose tubules are sometimes filled with the finely dispersed glauconite. Our data based on the detailed petrographic studies and SEM investigations confirm and supplement the opinion of several researchers about an important role of microbiota on the glauconite formation. The paper discusses different stages of the glauconite formation in sediments of the Kakert and Gakkha horizons and the possible setting of glauconite infilling in the algal borer trails and holes.
295-304
305-318
Trace elements in Upper Devonian rocks of the Andoma Hill zone of fold-and-fault dislocations (southeastern Onega region) as indicators of source areas
Abstract
The paper reports the results of lithogeochemical studies of the Upper Devonian rocks from the Andoma Hill zone of fold-and-fault dislocations (SE Onega region). The rocks are characterized by the negative Eu anomaly (from 0.4 to 0.65) that maks them different from modern sediments of the White Sea. The latter can be regarded as the average composition of mainly Archean (Karelian–Kola) part of the Baltic Shield. In terms of the contents of some trace elements, they also differ from the Vendian rocks of the Zimnii Bereg area. Since the considered rocks are geochemically similar to the Svecofennian metamorphic rocks and Paleoproterozoic granite rapakivi, they could be formed by the erosion of these complexes. The clastic material was transported via a channel confined to the Baltic Shield and Russian Platform junction known as the Polkanov geoflexure.
319-333
Erratum
Erratum to: “Criteria for the detection of hydrothermal ecosystem faunas in ores of massive sulfide deposits in the Urals”
Abstract
The ore-formational, ore-facies, lithological, and mineralogical-geochemical criteria are defined for the detection of hydrothermal ecosystem fauna in ores of the volcanic-hosted massive sulfide deposits in the Urals. Abundant mineralized microfauna is found mainly in massive sulfide mounds formed in the jasperous basalt (Buribai, Priorsk, Yubileinoe, Sultanov), rhyolite—basalt (Yaman-Kasy, Blyava, Komosomol’sk, Sibai, Molodezhnoe, Valentorsk), and the less common serpentinite (Dergamysh) formations of the Urals (O—D2). In the ore-formational series of the massive sulfide deposits, probability of the detection of mineralized fauna correlates inversely with the relative abundance of felsic volcanic rocks underlying the ores. This series is also marked by a gradual disappearance of colloform pyrite, marcasite, isocubanite, pyrrhotite, and pyrite pseudomorphoses after pyrrhotite; increase of the amount of bornite, fahlores, and barite; decrease of contents of Se, Te, Co, and Sn in chalcopyrite and sphalerite; and inсrease of Tl, As, Sb, and Pb in the colloform pyrite. Probability of the detection of mineralized fauna in the morphogenetic series of massive sulfide deposits decreases from the weakly degraded sulfide mounds to the clastic stratiform deposits. The degradation degree of sulfide mounds and fauna preservation correlates with the attenuation of volcanic intensity, which is reflected in the abundance of sedimentary and volcanosedimentary rocks and the depletion of effusive rocks in the geological sections.
334-334