We investigated the deep structure of the lithosphere and the geodynamic conditions of granitoid magmatism in the Eastern Russia within the borders of the Far Eastern Federal District. The relevance of the work is determined by the need to establish the geotectonic and geodynamic conditions of the granitoids petrogenesis and ore genesis in the Russian sector of the Pacific Ore Belt. The purpose of the article is to study the deep structure of the lithosphere and determine the geodynamic conditions of granitoid magmatism in the East of Russia. The author's data on the magmatism of ore regions, regional granitoids correlations, archive and published State Geological Map data, survey mapping, deep seismic sounding of the earth's crust, gravimetric survey, geothermal exploration, and other geophysical data obtained along geotraverses. The magma-controlling concentric geostructures of the region are distinguished and their deep structure is studied. The connection of plume magmatism with deep structures is traced. The chain of concentric geostructures of Eastern Russia controls the trans-regional zone of leucocratization of the earth's crust with a width of more than 1000 km, which includes the Far Eastern zone of Li-F granites. Magmacontrolling concentric geostructures are concentrated in three granitoid provinces: Novosibirsk-Chukotka, Yano-Kolyma, and Sikhote-Alin. The driving force of geodynamic processes and granitoid magmatism was mantle heat fluxes in the reduced zones of the lithospheric slab. The distribution of slab windows along the Pacific mobile belt's strike determines the location of concentric geostructures and the magnitude of granitoid magmatism in the regional provinces. Mantle diapirs are the cores of granitoid ore-magmatic systems. The location of the most important ore regions of the Eastern Russia in concentric geostructures surrounded by annuli of negative gravity anomalies is the most important regional metallogenic pattern reflecting the correlation between ore content and deep structure of the earth's crust.

The fall of the Chelyabinsk meteorite LL5 (Febru ary 15, 2013), the largest in the past century, caused a wide resonance in the scientific world and initiated the complex investigation of meteorite material. The results of such study have been reported in many pub lications ([1, 2] and others). In discussing the results of the isotope-geochemical study of this meteorite, we should primarily mention the local U-Pb dating of apatite in situ, which was performed independently by X. H. Li in Beijing, China (4452 ± 21 Ma [2]) and by K. Terada in Hiroshima, Japan (4433 ± 110 Ma [3]). Both ages are consistent within the error and, in opin ion of the authors [2, 3], correspond to the largest impact event which was registered by apatite in other meteorites as well (e.g., Novato L6 [4]) and highly likely this impact event was connected with the forma tion of the Moon. The older age (4538 ± 2 Ma) obtained by A. Bouvier [5] who used the isochron method for leached meteorite glass is correlated by the author with the impact event, rather than with cooling of the parental body of the meteorite after its forma tion. Based on the results of the study of rock forming minerals (olivine, orthopyroxene, and troilite) of the Chelyabinsk meteorite, the Sm-Nd isochron with an age of 3733 ± 110 Ma was plotted [6]. This is the age of an impact event, which resulted in melting of meteor ite material and re equilibration of the Sm-Nd iso tope system. Independent dating of the meteorite by the Sm-Nd method at the Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sci ences, was not performed for monomineral samples and did not provide a precise isochronous depen dence. A linear trend ("geochron") corresponding to an age of ~290 Ma was obtained [1]. The age of frag mentation of the parental body of the Chelyabinsk meteorite (the age of exposure) was estimated by the concentration of cosmogenic nuclides as ~1.2 Ma [7].One zircon grain (no. 1 in Tables 1 and 2) was found at the laboratory of the Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, during extraction of monofractions of rock forming minerals for Sm-Nd dating from samples with a total weight of 20 g by a methodology which excludes a laboratory contamination [6]. With account for the importance of the find, zircon extraction was repeated from the sample with a weight of ~70 g at the laboratory of the ZAO "NATI" by the "ppm mineral ogy" technology [8] (www.natires.com). This technol ogy was primarily worked out for extraction and study of heavy ore minerals, especially gold and PGE bear ing phases, at a low (<1 ppm) concentration of these phases in rock. Later this technology was adapted for extraction of zircon, apatite, and monazite. Distinct groups of heavy minerals` concentrates with a big range of densities were obtained and studied and this approach allows to achieve required mineralogical sensitivity. The process of gravitational fractionation was carried out on a hydroseparator designed in the ZAO "NATI." To prevent pollutio...

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The aim of this paper was to establish the causes of the heterogeneity of the chemical composition of the metal obtained by the LC technology. The powdered raw material was made from a monolithic alloy, which was fused by the SLM, the initial raw material was a laboratory melting metal of a low-carbon chromium-manganese-nickel composition based on iron. To determine the distribution pattern of alloying chemical elements in the resulting powder, electron-microscopic images of thin sections were combined with X-ray analysis data on the cross-sections of the powder particles. As a result, it was found that transition (Mn, Ni) and heavy (Mo) metals are uniformly distributed over the powder particle cross-sections, and the mass fraction of silicon (Si) is uneven: in the center of the particles, it is several times larger in some cases. The revealed feature in the distribution of silicon is supposedly due to the formation of various forms of SiO4 upon the cooling of the formed particles. The internal structure of the manufactured powder is represented by the martensitic structure of stack morphology. After laser fusion, etched thin sections revealed traces of segregation heterogeneity in the form of a grid with cells of ~ 200 μm.

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