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Том 51, № 3 (2016)
- Год: 2016
- Статей: 5
- URL: https://journals.rcsi.science/0024-4902/issue/view/9849
Article
Geological setting and lithological features of Cenozoic sediments in Ebelyakh Bay (Laptev Sea)
Аннотация
Materials of bottom sampling and drilling on Ebelyakh Bay, the Cape Svyatoi Nos area, and southern part of the Dmitry Laptev Strait by researchers from VNIIOkeangeologiya during the past 60 years and data on the geological setting of the Chokhchur–Chokurdakh zone (Ebelyakh Bay included) were also examined. The geology and lithology of Cenozoic sediments in the water area of the bay and adjacent land were scrutinized to elucidate mineral resources in the Earth’s interior in the study area. Analysis of the Upper Jurassic–Holocene summary section shows that terrigenous material was derived from (i) coastal zones composed of granitoid or contact metamorphic rocks, (ii) Quaternary friable sediments of marine terraces and beaches, (iii) submarine rises, and (iv) river discharge. It is shown that cassiterite is associated with the Pliocene–lower Pleistocene Serkino horizon and Holocene sediments. New promising cassiterite areas have been revealed. The results suggest that prospecting for tin placers should be continued at Ebelyakh Bay.
161-178
Lithogeochemistry of rocks of the Upper Neopleistocene Ust-Oda reference section in the Irkutsk Amphitheater of the Siberian Platform
Аннотация
The results of study of rocks of the Ust-Oda section, one of the key outcrops of Upper Neopleistocene sediments in the Irkutsk Amphitheater of the Siberian Platform, are presented. It is shown that primary sediments were deposited in the Neopleistocene under subarid conditions and relatively high sedimentation rates. Similar contents of trace elements in all rock lithologies suggest that the provenance was unaltered during sedimentation. It is shown that variation in the sediment transport mechanism is one of the signs of changes in the paleoclimatic setting. Climatic cyclicity of the Ust-Oda section formation and succession of sedimentation setting, which were reconstructed on the basis of grain size data, correspond to variations in the petrochemical correlations and geochemical coefficients.
179-194
Isotopic composition (δ13C and δ18O) and genesis of carbonates from the famennian manganiferous formation of Pai-Khoi
Аннотация
The results of isotope-geochemical studies of carbonates of different mineral types from manganese and host rocks of the Famennian manganiferous formation of Pai-Khoi are reported. Kutnahorite ores are characterized by δ13C values from–6.6 to 1.3‰ and δ18O from 20.0 to 27.4‰. Rhodonite–rhodochrosite rocks of the Silovayakha ore occurrence have δ13C from–5.2 to–2.9 and δ18O from 25.4 to 24.3‰. Mineralogically similar rocks of the Nadeiyakha ore occurrence show the lighter carbon and oxygen isotopic compositions: δ13C from–16.4 to–13.1 and δ18O from 24.8 to 22.5‰. Similar isotopic compositions were also obtained for rhodochrosite–kutnahorite rocks of this ore occurrence: δ13C from–13.0 to–10.4‰ and δ18O from 24.6 to 21.7‰. Siderorodochrosite ores differ in the lighter oxygen and carbon isotopic compositions: δ18O from 18.7 to 17.6‰ and δ13C from–10.2 to–9.3‰, respectively. In terms of the carbon and oxygen isotopic compositions, host rocks in general correspond to marine sedimentary carbonates. Geological-mineralogical and isotope data indicate that the formation of the manganese carbonates was related to the hydrothermal ore-bearing fluids with the light isotopic composition of oxygen and carbon dissolved in CO2. The isotopic features indicate an authigenic formation of manganese carbonates under different isotopegeochemical conditions.
195-213
Genetic types of metaconglomerates at the Paleoproterozoic basement of the Krivoi Rog iron ore basin
Аннотация
The Paleoproterozoic basement of the Krivoi Rog iron ore basin comprises five genetically different lithopetrographic types of metaconglomerates that make up stratigraphic and lithofacies successions ranging from the proluvial to shallow-basin formations. The dominant type is represented by the basal flow (proluvial and alluvial) metaconglomerates. Variations in the lithopetrography of metaconglomerates reflect the evolution of paleofacies and paleotectonic constraints.
214-227
Lower–Middle Devonian rocks at junction of the Volga–Ural anteclise, Ural foredeep, and North Caspian basin: Lithology and perspectives of petroleum potential
Аннотация
New data on the stratigraphy and lithology of the Lower–Middle Devonian rocks at junction of the Volga–Ural anteclise, Ural foredeep, and North Caspian basin are reported. Facies maps are also presented for the Takatinian, Koiva–Vyazov, Eifelian, and Givetian stages of the region evolution. The paleogeographic evolution and structural zonation of the basin in the Early–Middle Devonian are discussed. The evolution of carbonate buildups (Akbulak and Saraktash) in connection with their possible petroleum potential is examined.
228-241