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Isotopic dates newly obtained for the northwestern portion of the Angara–Vitim batholith are consistent with preexisting data on the duration of the Late Paleozoic magmatic cycle: 55–60 Ma (from 325 to 280 Ma). These data also indicate that alkaline mafic magmatism in western Transbaikalia began simultaneously with the transition from crustal granite-forming processes to the derivation of granites of a mixed mantle–crustal nature, with gradual enrichment of the juvenile component in the source of the magmas. Analysis of the currently discussed geodynamic models of Late Paleozoic magmatism shows that a key role in all models of extensive granite-forming processes in the region is assigned to mafic mantle magmas, which can be generated in various geotectonic environments: subduction, delamination, decompression, and a mantle plume. The plume model is most consistent with the intraplate character of the Angara–Vitim batholith. The derivation of the vast volume of granitic material (approximately 1 million km3) should have required a comparable volume of mafic magma that should have been pooled in the middle crust of the Baikal fold area. However, the density structure of the region does not provide evidence of significant volumes of mafic rocks. This suggests that the mechanism of plume–lithospheric interaction that should have induced extensive crustal melting and the origin of vast granite areas was more complicated than simply conductive melting of crustal protoliths in contact with mafic intrusions. 相似文献
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Damdinov B. B. Damdinova L. B. Khubanov V. B. Yudin D. S. Travin A.V. Buyantuev M. D. 《Geology of Ore Deposits》2020,62(3):225-247
Geology of Ore Deposits - The article discusses the features of the composition, age, and genesis of gold–antimony mineralization of the East Sayan based on the example of the largest... 相似文献
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S. I. Shkolnik E. F. Letnikova A. V. Maslov M. D. Buyantuev L. Z. Reznitskii I. G. Barash 《Doklady Earth Sciences》2017,475(1):739-742
The results of geochemical, mineralogical, and isotope (U–Pb and Sm–Nd) studies of metasedimentary manganese-bearing rocks from the Itantsa Formation of the Ikat terrane are presented. It is found that the carbonate-effusive-shale complex of the Itantsa Fm. formed under the continental margin environment, with volcanic activity accompanying sedimentation, in the interval of 650–540 Ma ago. 相似文献
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S.G. Arzhannikov A.V. Ivanov A.V. Arzhannikova E.I. Demonterova M. Jolivet V.I. Voronin V.A. Buyantuev V.A. Oskolkov 《Russian Geology and Geophysics》2017,58(1):20-36
Dendrochronology and radiocarbon dating, with reference to remote sensing, digital elevation modeling, geological, and geomorphological data, provide new age constraints for the Jombolok lava field in the East Sayan Mountains (Siberia). The Jombolok lava field originated in the latest Late Pleistocene and underwent at least four phases of volcanic activity recorded in lava flows. Two earliest phases followed shortly one after another more than 13 kyr ago. The third phase corresponding to eruptions of Kropotkin volcano can be timed only relatively. The fourth phase has been dated by dendrochronology and AMS 14C of well-preserved wood buried under the youngest lava which occurs among older lavas near the Jombolok River mouth. The age of this activity is bracketed between the death of trees caused by eruptions 1268-928 years ago and the beginning of new tree growth on the surface of the most recent lavas 900 years ago. 相似文献
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