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The article is devoted to the fundamental problem of modern genetic hydrogeochemistry and petroleum hydrogeology — to clarify the nature and age of the brines dominating in hydrostratisphere of epi-Karelian platforms. On the basis of more than 500 analyzes of macro- and micronutrients we made a geochemical typification of Volga-Ural brines and presented our ideas about their formation and origin. The genesis of calcium chloride brines was associated with the processes of density convection of uterine magnesium chloride brine from the Lower Permian evaporite paleoreservoir into the underlying Paleozoic complexes and its subsequent metamorphism mainly due to the metasomatic dolomitization of limestones. The epigenetic character of calcium chloride brines was confirmed by hydrogeochronological estimates made by a kinetic-geochemical method. The interpretation of geochemical genetic information indicated a possible contribution of the Urals in the oil and gas potential of the Volga-Ural region.

Keywords: Volga-Ural oil and gas basin, brines, formation, origin, age.

DOI: 10.19110/2221-1381-2016-4-3-6

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We present the results of our study of the Upper Proterozoic and Upper Cambrian-Lower Ordovician sandstones in the Northwestern Pay-Khoy Ridge to find diagnostic lithochemical criteria for the paleontological silent strata genesis. We established that oceanic island arc had been the area of formation of tuffaceous Late Riphean-Vendian sandstones of morozovskaya and sokolninskaya formations and island arc volcaniclastics — the main source of detritus. We revealed the affiliation of the Upper Cambrian-Lower Ordovician sandstones of hengurskaya formation to sedimentary coastal-marine formations formed under the conditions of active and passive continental margins. We found that a significant role in the formation of their structure, alongside with basic and intermediate volcanics compositions, was played by metasedimentary rocks, and especially the material composition of the hengurskaya sandstones supports their value as a target for ancient metamorphosed placer.

Keywords: sandstone, chemical composition, clastic material, formation area, conditions of sedimentation, volcanics.

DOI: 10.19110/2221-1381-2016-4-7-16

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The paper embraces results of the Holocene alluvium in the Izhma, Vym’ and Vychegda rivers valleys study. The study is concerned with succession of paleogeographical events during Holocene in the south-western Timan-Pechora-Vychegda region. Conditions of the sedimentation and the alluvium facies depending on the rivers location in different geological areas have been identified by lithological methods. Pollen data provide a basis for reconstruction of vegetation and climate dynamics. Four stages of vegetation and climate changes have been reconstructed in the Izhma and Vym’ rivers valleys. Seventeen stages have been reconstructed in the Vychegda river valley in consequence of occurrence of older valley peat bogs there.

Keywords: Holocene, paleogeography, palinology, alluvium, facies.

DOI: 10.19110/2221-1381-2016-4-17-23

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The Lower Silurian Lower Devonian of the NW of Yugra Peninsula (NW of the Pay-Khoy carbonate parautochthone) is represented by organogenous carbonates 330—350 m thick. The new Loseva Formation, comprising these deposits, is proposed. The formation overlays the Late Ordovician Sarmik Fm. (O₃sr), and is overlaid by the Early Devonian Rif Fm. (D₁rf). The Loseva Fm. (S₁-D₁ls) is composed of gray organogenous limestones with numerous algal and bryozoan and stromatoporoid buildups, and their debris fans. The areal stratotype of the Loseva Fm. is located in the Loseva Cape. The characteristic features of the formation are the following: presence of numerous algal and bryozoan and stromatoporoid buildups; mainly gray colored sediments. The formation age ranges from the Early Silurian through the Lokhovian (Early Devonian).

Keywords: Loseva Formation, Silurian, Lower Devonian, stratigraphy, Pay-Khoy.

DOI: 10.19110/2221-1381-2016-4-24-28

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The article presents the results of study of mineral colors with icons of the 18th century “The Holy Virgin of three hands”, “Archangel Michael the terrible Governor”, “St. Nicholas the Wonderworker”. Natural paint was studied by X-ray, X-ray fluorescent and microprobe analyses. It was established that pigments with similar chemical and mineral composition were used in all three icons. The red pigment was vermilion. The brown pigment was ochre illite-montmorillonite composition with phase iron of smectite composition. Blue-green pigment had mainly a montmorillonite composition. The similar chemical and mineral composition resulted in our conclusion about the source material for all three icons, hypothetically attributable to different icon-painting workshops - Velikopozhensky monastery and Vygoleksinsky community.

Keywords: mineral paints, pigments, icons, Velikopozhensky monastery, Vygoleksinsky community.

DOI: 10.19110/2221-1381-2016-4-29-33

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