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51.
A.G. Doroshkevich G.S. Ripp S.A. Sergeev D.L. Konopel’ko 《Russian Geology and Geophysics》2012,53(2):169-174
We present results of U-Pb (SHRIMP II) geochronological study of the rocks of the Mukhal alkaline massif in the Vitim alkaline province, western Transbaikalia. The available K-Ar and Rb-Sr dates for the alkaline rocks (Saizhen complex) of the Vitim province, including the Mukhal massif, vary over a broad range of values. The obtained age of crystallization of the Mukhal urtites refines the time when the regional alkaline magmatism began. The age of zircons and magmatic processes within the Barguzin area (315–275 Ma) is close to the peak of main events, which occurred between 295 and 275 Ma. These processes took place at the early stage of evolution of the Late Paleozoic rift system in Central Asia, whose activity was associated with the activity of mantle superplume. 相似文献
52.
I.A. Izbrodin G.S. Ripp A.G. Doroshkevich S.A. Sergeev D.I. Matukov V.F. Posokhov 《Russian Geology and Geophysics》2010,51(2):186-189
Results of U-Pb (SHRIMP II) and Rb-Sr dating of sillimanite schists in southwestern Transbaikalia are presented, which testify to high-temperature metamorphism in the Late Mesozoic. The metamorphism might have been related to the formation of metamorphic cores or tectonoplutonic activity accompanied by the formation of rift structures in Transbaikalia and Mongolia. 相似文献
53.
54.
G. S. Ripp A. G. Doroshkevich E. I. Lastochkin I. A. Izbrodin 《Geochemistry International》2014,52(4):271-286
We present the results of a study on gabbroic rocks, syenites, pegmatites, carbonatites, and hydrothermal products of the Oshurkovo apatite-bearing massif. The results include Nd and Sr isotope ratios; the isotope compositions of carbon and oxygen in calcite; oxygen in apatite, magnetite, and silicate minerals (phlogopite, titanite, diopside, amphibole, K-feldspar, and quartz); sulfur in barite; and hydrogen in mica. The isotopic data are close to the EM-1 enriched mantle values and confirm a comagmatic relationship between the gabbros and carbonatites. The binary plot ?Nd vs. 87Sr/86Sr demonstrates strong differentiation between silicate rocks and carbonatites, as is the case with the other Late Mesozoic carbonatite occurrences of southwestern Transbaikalia. The oxygen isotope composition of all comagmatic phases also falls within the range of mantle values. A clear trend toward heavier oxygen and lighter carbon isotope compositions is observed in all successively emplaced phases, which is consistent with a trend defined by hydrothermal products formed under the influence of the parent magma chamber. Carbonates formed during the greenstone alteration of gabbroic rocks are enriched in the light oxygen isotope (δ18O from ?2.8 to ?7.3‰), suggesting a contribution of vadose water. 相似文献
55.
Astronomy Reports - An analysis of the properties of 1157 galaxies, groups and clusters of galaxies confirms the dependence of the virial velocity on the halo mass $${{v}_{{{\text{vir}}}}} =... 相似文献