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The results of geochronological (U-Pb), isotope-geochemical (Lu-Hf), and geochemical (REEs) studies of young (MZ, KZ) and xenogenic (AR, PR) zircons from magmatic rocks of the Central Arctic rises of the Arctic Ocean (AO) and the crest zone of the Mid-Atlantic Ridge (MAR) are presented. The data obtained show that the depleted mantle could be a source of young (KZ) zircons of the MAR, whereas young (MZ) zircons of the MAR and all xenogenic (AR, PR) zircons of the AO and MAR are from crustal rocks of the continental lithosphere. [ABSTRACT FROM AUTHOR]

Granites, especially those that were decompressed as a result of processes of secondary transformations and tectonic movements, hold the greatest potential in the search for oil-bearing rocks in basements of sedimentary basins. Owing to the chemical dating of monazites from collision granites of the East Shebur area, the isochrone age of 274.5 ± 21 Ma was obtained. Zircons (SHRIMP-II) yield a concordant age of 277.5 ± 2 Ma (MSWD = 0.77). The Rb-Sr isochrone age of granites (247.4 ± 9.1 Ma) coincides with the emplacement time of the West Siberian rift system. This age records the process of intruding East Shebur granites into the upper crust level during riftogenesis and the extension of the study area. The younger age datings (231 Ma, 60 Ma (U-Pb); 220 Ma (K-Ar)) record the stages of tectonomagmatic activation, recorded in the basement of the Western Siberia oil-bearing areas. [ABSTRACT FROM AUTHOR]

Economic copper, nickel, and platinum-group element (PGE) deposits are associated with the Talnakh ultramafic-mafic intrusion of the Noril'sk Province in the northwestern part of the Siberian Platform. The results of the chemical Th-U-Pb dating of monazite from the ore-bearing melanotroctolites of the Talnakh intrusion are presented. The isotope-geochemical features of monazite are compared with zircon, sulfides, and baddeleyite. [ABSTRACT FROM AUTHOR]

This work presents the results of U-Pb isotope dating of zircons from granodiorites and plagiogranites of the Tallainskii gabbro-granodiorite-plagiogranite complex of the Karalon-Mamakan zone of the Baikal-Muya belt, ascribed to the Tallainskii pluton. The age datings obtained for granodiorite of the Eleninskii massif (605 ± 6 Ma) and plagiogranite of the Ust-Berezovo massif (609 ± 6 Ma) are in close agreement within the limits of error. Taking into account previously published data, the emplacement of the Tallainskii complex occurred within the age interval of 615-603 Ma in connection with postcollision extension. The 'island arc' geochemical characteristics of granodiorites and plagiogranites can be explained by magmatic differentiation and (or) participation in the formation of a melt source enriched in the suprasubduction component involved in petrogenesis during the preceding Neoproterozoic period. [ABSTRACT FROM AUTHOR]

The article discusses the geochronological study of the trachyrhyolites of the Ulkan Group. It states that the volcanic deposits overlie metamorphic rocks of the Early Proterozoic era. It mentions that Riphean deposit sequence is considered as Siberian hypostratotype. It adds that isochronous Rb-Sr method was used to identify the age of the crust located at the base of Lower Riphean Uyan Group. Furthermore, the chemical composition of volcanites correspond to igneous rocks while associated granites and acid volcanites correspond to granites which are A-type.

The article presents a study on the age determination of the rare earth element (REE) distribution in Zircon from a granitoid sample from the Southern Prince Charles Mountains in Eastern Antarctica. It states that the presence of Ruker granite in the area indicates a series of felsic orthogneiss, metasedimentary and volcanic events. The researchers used a titanium geothermometer to estimate the crystallization temperature of zircon in the area. It concludes that the Sodruzhestva Series in the area was formed in the post-Archean time because signs of Archean - Paleoproterozoic tectonothermal processes are absent in the samples.

The article discusses the method of isotope-geochronological timing of rock metamorphism at the boundary zone of Aldan Shield and the Dzhugdzhuro-Stanovoi Folded Area in the area of Nagornyi Village and Kholodnikan Pass in Russia. The method indicated an overthrust-sheet structure that developed in the zone and a tectonic plate that moderately points to the south. Further observations showed that the metamorphic rocks are deformed linearly or folded isoclinally in the latitudal direction parallel to the whole junction zone.

The article discusses the study on the mineralogy, geochemistry and age peculiarities of zircon distribution on gneissose leucocratic miaskites of the Ilmenogorsk massif deposit at the southern region of Ural Mountains in Russia. Researchers conducted recrystallization of the zircon samples from amphibole miaskites that yielded formation of emulsion structures, crushing and corrosion, and new growth. From the authors' findings, ages of miaskite crystallization, 434 plus 15 minus 10 million years (Ma), and metamorphism, 239 plus 40 minus 45 Ma, were determined by standard uranium-lead (U-Pb) dating method.