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Nikiforov A. V. Ivanova A. A. Yarmolyuk V. V. Salnikova E. B. Kotov A. B. Kozlovsky A. M. Khertek A. K. Plotkina Yu. V. Kudryashova E. A. Galankina O. L. Polyakov N. A. 《Doklady Earth Sciences》2023,507(3):S382-S389
Doklady Earth Sciences - The temporal relations between alkaline rocks of the Aryskan rare metal (Y, REEs, Nb, Ta) deposit are determined using metamict zircon with high U and Th contents, which... 相似文献
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Water Resources - The article presents the results of summer dry-season areal surveys of subsoil water chemistry in the drainage basin of the Ivankovo Reservoir in the Volga segment from Tver City... 相似文献
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F. M. Stupak V. A. Lebedev E. A. Kudryashova 《Journal of Volcanology and Seismology》2012,6(3):172-183
We provide a new scheme to classify Late Cenozoic volcanic rocks in the Udokan lava plateau based on isotope datings of rocks derived during the last 15 years. The scheme distinguishes five structural-material complexes (SMCs): Middle Miocene, Late Miocene, Early/Middle Pliocene, Late Pliocene, and Quaternary. Each SMC has its ejecta of central-type eruptions and subvolcanic emplacement episodes that classify themselves into individual rock complexes, while the ejecta of mass fissure effusions from three SMCs (the Late Miocene, the Early/Middle Pliocene, and the Late Pliocene) can be lumped into three stratigraphic series. Each series includes three suites, with the middle position (in the series section) being occupied by suites composed of basaltic melt differentiates. 相似文献
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V. V. Yarmolyuk V. I. Kovalenko A. M. Kozlovsky V. P. Kovach E. B. Sal’nikova D. V. Kovalenko A. B. Kotov E. A. Kudryashova V. I. Lebedev G. Eenzhin 《Petrology》2008,16(7):679-709
The paper reports data on the evolutionary history of magmatism, its conditions, and sources in the process of the development
of the Southern Mongolian Hercynides during the pre-accretion, continental-margin, and rifting stages within the time span
from the Silurian to Early Permian. The Hercynian continental crust in the southern Mongolian segment of the Central Asian
Foldbelt (CAFB) was determined to have grown in the environment of ensimatic island arcs, backarc basins, spreading centers,
and oceanic islands or plateaus, with material coming from the depleted and, perhaps, also enriched mantle sources in the
open ocean that surrounded the Siberian paleocontinent on the side of the Caledonian margin. This made it possible to recognize
the Early-Middle Paleozoic epoch of juvenile crustal growth in CAFB and the corresponding isotopic crustal province with a
total area of more than 200 thousand km2. The principal differences between the composition and structure of the blocks surrounding the Hercynian regions (Caledonides
in the Gobi Altai and Grenwillides in the South Gobi microcontinent) testify that the southern margin of the Caledonian Siberian
continent and the Grenvillides of the South Gobi microcontinent had different geological histories and were spatially separated.
The structural complex of the Paleoasian ocean, including the terranes of the South Gobi microcontinent, were transformed
into a continental block in the latest Devonian-earliest Carboniferous, in relation with accretion processes, folding, metamorphism,
and tectonic delamination along the boundaries of structurally heterogeneous domains. The subsequent recycling of the crust
by magmatic processes was related to the development of an active continental margin (ACM). The development of an ACM in the
Hercynides resulted from and was a continuation of the motions of the continental and oceanic lithospheric plates, i.e., processes
that brought about the Hercynian accretion. The evolution history of the ACM was subdivided into two stages: early (a continental-margin
stage proper) and late (rifting stage). The rocks of the early stage were produced at 350–330 Ma and compose a differentiated
basalt-andesite-rhyodacite complex and related massifs of the granodiorite-plagiogranite and banatite (diorite-monzonite-granodiorite)
associations. During the rifting stage at 320–290 Ma, a bimodal basalt-comendite-trachyrhyolite association was formed, along
with accompanying alkali granite massifs. In the southern Mongolian segment of the Hercynides, the rocks of the rifting stage
compose two subparallel rift zones: Gobi-Tien Shan, which extends along the boundaries of the South Gobi microcontinent, and
the Main Mongolian lineament, which marks the boundaries between the Hercynides and Caledonides in the CAFB. The rift structures
are made up of alkali granitoids and normal-alkalinity granitoids, which are atypical of rift zones. Their genesis is thought
to have been related to crustal anatexis, a process that was triggered by rift-related magmas at an unusual combination of
rifting and ACM tectonic setting. The basic rocks of the rift associations have geochemical signatures atypical of continental
rifting. They show Ta and Nb minima and K and Pb maxima, as is typical of rocks generated at convergent plate boundaries.
Nevertheless, the broad variations in the concentrations and ratios of some major and incompatible trace elements and in the
Sr, Nd, and O isotopic composition of the rift basaltoids allowed us to distinguish their high-and low-Ti varieties, which
were produced with the participation of three mantle sources: depleted mantle similar to the source of basalts in midoceanic
ridges, enriched mantle like the source of basalts in oceanic islands, and the mantle material of the metasomatized mantle
wedge. The origin of andesites in the rift zones is explained by the contamination of mantle basaltoid melts with sialic (predominantly
sedimentary) material of the continental crust or the assimilation of anatectic partial granite melts. 相似文献
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E. A. Kudryashova V. V. Yarmolyuk A. M. Kozlovsky V. M. Savatenkov 《Doklady Earth Sciences》2010,432(1):565-569
The concentric zonal structure of the Late Cenozoic volcanism areal in Central Mongolia which is situated on the territory
of the Khangai vault has been educed. The central part of the structure conforms to the axial part of the vault and is presented
with volcanic fields of the Watershed graben and newest valley flows. The peripheral zone is presented with volcanic fields
located along the vault frame (Taryat graben, Lake Valley graben, and grabens of the Orkhon-Selenga interfluve). The structural
zoning of the areal comports with the substantial zoning of volcanism products. The rocks of the central part have isotopic
(Sr, Nd, Pb) and geochemical characteristics conforming to the most primitive (like PREMA) compositions of mantle sources
of magmatism. Magmatism sources in the peripheral zone of the volcanic areal, besides the PREMA mantle, contained a substance
of enriched mantle like EMI. The character of substantial and structural zoning of volcanism is caused by the influence of
the mantle plume on the Central Asia lithosphere. According to geophysical and isotopic-geochemical data, this plume had a
lower mantle nature. 相似文献
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Late Cenozoic volcanic province in Central and East Asia 总被引:2,自引:0,他引:2
The paper presents materials on the inner structure of the Late Cenozoic within-plate volcanic province in Central and East
Asia, in which two subprovinces are distinguished: Central Asian and Far Eastern, which comprise a number of autonomously
evolving volcanic areas. Some of the volcanic areas are proved to have evolved for a long time, starting in the Late Mesozoic.
In spite of differences in their age and structural setting, the volcanic areas evolved according to similar scenarios in
the Late Cenozoic. Magmatism in the province was related to a mantle source of the within-plate type. The magmatic associations
are dominated by mafic alkaline high-K rocks. The rocks are geochemically close to basalts of the OIB type, and their isotopic
composition corresponds to a combination of mantle sources of the PREMA, EMI, and EMII types at the predominance of PREMA.
Geological, geochemical, and isotopic lines of evidence suggest that magmatism in the province was related to mantle plumes.
This is consistent with geophysical data, which testify that the volcanic areas are underlain by upwellings of the asthenospheric
mantle or plumes. Seismic tomography data indicate that the “stems” of the plumes can be traced down to the upper and lower
mantle. The province is thought to have been produced when the eastern margin of the Asian plate overlapped one of the branches
of the Pacific superplume at approximately 160 Ma. This branch of the superplume is pronounced in the modern mantle structure
as a cluster of mantle plumes that control (according to seismic tomography data) the interaction zone of the Pacific and
Asian lithospheric plates. 相似文献
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Yarmolyuk V. V. Kozlovsky A. M. Nikiforov A. V. Kudryashova E. A. Hertek A. K. 《Doklady Earth Sciences》2021,499(1):556-563
Doklady Earth Sciences - The age and geochemical characteristics of alkaline rocks of the Dugda massif (Eastern Tuva), attributed to the East Sayan Late Paleozoic rare-metal magmatic zone, have... 相似文献