排序方式: 共有170条查询结果,搜索用时 593 毫秒
21.
22.
The Earth's crust faults and lineaments group in clusters with predominant N-S and E-W (System I) and NW-SE and NE-SW (System II) directions. The earthquake epicenters of the Benioff seismofocal zones follow the same regularities. In other words, seismofocal zones (epicenters of earthquakes) constitute a part of the regular network of the Earth's crust and lithosphere faults and lineaments. Mathematical modeling of stress distribution in the lithosphere due to a change of the Earth's ellipsoid compression showed that the principal stresses σ1 and σ2 are oriented in N-S and E-W directions, while corresponding shear stresses τ are oriented in NE-SW and NW-SE directions. It is shown that the secular deceleration of the Earth's rotation can be a reasonable mechanism for the change of Earth's ellipsoid compression and, consequently, for the origin of the regular system of faults and lineaments described above. 相似文献
23.
24.
25.
Maslov A. V. Politova N. V. Klyuvitkin A. A. Kozina N. V. Kravchishina M. D. Novigatsky A. N. Novichkova E. A. Shevchenko V. P. 《Doklady Earth Sciences》2022,507(2):1124-1131
Doklady Earth Sciences - The systematics of REE, Sc, Cr, Zr, and Th in silty-pelitic and pelitic surface bottom sediments sampled during cruises 71, 75, 77, and 80 of the R/V Akademik Mstislav... 相似文献
26.
Maslov A. V. Nemirovskaya I. A. Shevchenko V. P. 《Lithology and Mineral Resources》2022,57(3):181-198
Lithology and Mineral Resources - The main geochemical characteristics of gray silts of the Volga Reservoir cascade are discussed. Together with sandy varieties, they occupy more than 60% of the... 相似文献
27.
Maslov A. V. Krupenin M. T. Ronkin Yu. L. Gareev E. Z. Lepikhina O. P. Popova O. Yu. 《Lithology and Mineral Resources》2004,39(4):357-381
General trends of the formation of Middle Riphean fine-grained aluminosiliciclastic rocks in the Bashkir Meganticlinorium are considered. It is shown that Yurmatinian shales do not contain any significant pyroclastic admixture. Judging from the relatively constant Th/Cr ratio throughout the Yurmatinian section, the tectonic regime in the study territory during the early Middle Riphean is suggested to be rather stable. The main paleoclimatic indices and indicators of the pelitic material maturity (CIA, CIW, IVC, PIA, and Ce/Y) suggest that paleodrainage systems in the early Middle Riphean were dominated by humid climate that gave way to the arid or semiarid type in the middle Yurmatinian. The low Mo/Mn ratio and some other indicators of redox conditions in shales from all Yurmatinian lithostratigraphic units show that no explicit reducing conditions existed in the basin during the early Middle Riphean. The shales were characterized by the increase in K2O/Al2O3 ratio, gradual enrichment in REE, and growth of LREE/HREE and LaN/YbN ratios toward the middle Yurmatinian, indicating the gain of an appreciable amount of slightly weathered arkosic aluminosiliciclastic material in the sedimentary basin about 1220–1200 Ma ago. The REE distribution and the UCC- and AUC-normalized shale compositions suggest that the eroded upper crust was compositionally close to the UCC. The occurrence of mafic and ultramafic rocks is also inferred. Data points of Yurmatinian shales plotted in the Cr–Ni, Eu/Eu*–GdN/YbN, and (La/YB)N–YbN diagrams are localized between the fields of Upper Archean and post-Archean rocks or within the latter field. Hence, post-Archean igneous and metamorphic complexes prevailed in paleodrainage systems of the early Middle Riphean. This is also confirmed by the model Nd ages. 相似文献
28.
Maslov A. V. Politova N. V. Shevchenko V. P. Kozina N. V. Novigatsky A. N. Kravchishina M. D. 《Doklady Earth Sciences》2019,485(1):298-302
Doklady Earth Sciences - The Co, Hf, Ce, Cr, Th, and REE characteristics are analyzed for modern sediments collected by a bottom grab during the 67th and 68th cruises of R/V Akademik Mstislav... 相似文献
29.
Medvedeva M. A. Vozbrannaya A. E. Sirin A. A. Maslov A. A. 《Izvestiya Atmospheric and Oceanic Physics》2017,53(9):1072-1080
Izvestiya, Atmospheric and Oceanic Physics - The capabilities of several multispectral satellite data types to identify the status of peatlands affected by peat extraction and abandoned deposits... 相似文献
30.
Yu. L. Ronkin G. Yu. Shardakova A. V. Maslov E. S. Shagalov O. P. Lepikhina 《Stratigraphy and Geological Correlation》2009,17(2):137-145
Petrogeochemical and isotopic-geochronological signatures in granitoids developed in structures with complex geological history represent an important feature for reconstructing paleogeodynamic settings. Granitoids are widespread in the western slope of the Urals, where the Uralian Orogen contacts via a collage of different-age blocks of the east European Platform. The Ufalei block located in the Central Urals megazone at the junction between the South and Middle Urals’ segments represents one such boundary structure with multistage geological evolution. The isotopic ages obtained by different methods for acid igneous rocks range from 1290 to 245 Ma. We determined close Rb-Sr and Sm-Nd ages (317 Ma) for granites of the Nizhnii Ufalei Massif. By their petrochemical parameters, granitoids and host granite-gneisses differ principally from each other: the former are close to subduction-related, while the latter, to continental-riftogenic varieties. The primary ratio (87Sr/86Sr)0 = 0.70428 and ?Nd ≈ +4 values indicate significant contribution of oceanic (island-arc?) material to the substrate, which served as a source for granites of the Nizhnii Ufalei Massif. Model Nd ages of granites vary from 641 to 550 Ma. Distinct oceanic rocks and varieties with such ages are missing from the surrounding structures. New isotopic dates obtained for ultramafic and mafic rocks from different zones of the Urals related to the Cadomian cycle imply development of unexposed Upper Riphean-Vendian “oceanic” rocks in the central part of the Ufalei block, which played a substantial role in the formation of the Nizhnii Ufalei granitoids. Such rocks could be represented, for example, by fragments of the Precambrian Timanide-type ophiolite association. The analysis of original materials combined with published data point to the heterogeneous composition and structure of the Ufalei block and a significant part of the western segment of the Central Uralian Uplift and extremely complex geological history of the region coupling the Uralian Orogen with the East European Platform in the present-day structure. 相似文献