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The Komsomolsk tin-ore district is located along the Miao-Chan Ridge in the Middle Amur River area (Khabarovsk krai) within the Badzhal accretionary terrane of the Sikhote-Alin orogenic belt. This work presents new results of U–Pb zircon dating of tonalite from the Miao-Chan complex of the Silinka granite pluton (99.7 ± 1.1 Ma) and rhyolites of the lower part of the Kholdami Formation (98.4 ± 1.0 and 98.7 ± 1.2 Ma) from the northeastern part of the Komsomolsk district. The geochemical characteristics of the rocks studied show that granitoids of the Miao-Chan complex are I-type rocks and that synchronous rhyolites of the Kholdami Formation are highly aluminous and correspond to S-type rocks. New data on the composition and early Cenomanian age of the rocks make it possible to consider the ore-magmatic system of the Komsomolsk ore district as part of the previously identified Albian–Cenomanian igneous province of Pacific Asia. [ABSTRACT FROM AUTHOR]

The first data of U–Pb isotopic study (LA–ICP–MS method) of zircon from tonalite–granodiorite forming a dominant part of the "trondhjemite" intrusive massif at the giant Tyrnyauz W–Mo deposit (North Caucasus) is presented. The concordant zircon isotopic U–Pb age obtained (302 ± 4 Ma) indicates a Late Paleozoic (Late Carboniferous–Early Permian) age of crystallization of these rocks. This is consistent with the Late Paleozoic epoch of W-bearing magmatism and related W mineralization in the North Caucasus (Peredovoi Ridge) and allows the possibility of the Late Paleozoic age of the large bodies of altered skarn with W mineralization at the Tyrnyauz deposit. [ABSTRACT FROM AUTHOR]

The Uyandina–Yasachnaya volcanoplutonic belt (UYVB) is located in Northeast Asia. As one of the largest volcanic belts in the region, it extends for 900 km from the headwaters of the Kolyma River in the northwesterly direction. The Late Jurassic UYVB overlaps the folds of the Cherskii collision belt. The UYVB rocks are characterized by highly variable facies indicating the heterogeneous nature of the belt. The UYVB has been studied at the cross section of the Indigirka River. This paper reports the first data on U–Pb dating of zircons and the geochemical features of rocks. The concordant U–Pb age of volcanic rocks is 150 ± 2–152 ± 2 Ma (Kimmeridgian–Volgian of the Late Jurassic). It is concluded that the formation conditions of the volcanic rocks change upward through the section, from those typical of mature island arcs to those more typical of active continental margins. [ABSTRACT FROM AUTHOR]

Based on geochronological U-Pb studies, the age of Wrangel Island granitoids was estimated as Neoproterozoic (Cryogenian). Some granitoids contain zircons with inherited cores with an estimated age of 1010, 1170, 1200, and >2600 Ma, assuming the presence of ancient (Neoarchean-Mesoproterozoic) rocks in the Wrangel Island foundation and their involvement in partial melting under granitoid magma formation. [ABSTRACT FROM AUTHOR]

The results of Sm-Nb isotopic-geochemical studies of metasedimentary and metavolcanic rocks of the Dzheltulak Group of the central part of the Dzheltulak suture, as well as geochronological U-Th-Pb (LA ICP MS) studies of detrital zircons from metasedimentary rocks, which are considered as Paleoproterozoic in current stratigraphic schemes, are presented. The age of the youngest zircons is 170-190 Ma, whereas the age of the last stage of regional metamorphism is 140-150 Ma. Thus, the Dzheltulak Group hosts metasedimentary rocks, the age of the protolith of which ranges from 140-150 to 170-190 Ma. The detrital zircons derived from intrusive and metamorphic rocks of the Selenga-Stanovoi and Dzhugdzhur-Stanovoi superterranes. [ABSTRACT FROM AUTHOR]

This report presents the results of U-Pb-geochronological studies (LA-ICP-MS) of detrital zircons from metasedimentary rocks of the west of the Yankan terrane (one of the largest within the structure of the Mongolian-Okhotsk mobile belt). The performed studies ascertain sufficiently the current notions of the geological development of the terrane. It is shown that the rocks are different in age from the main populations of detrital zircons and in the Sm-Nd isotope-geochemical characteristics. In view of this, one may suppose that these rocks do not belong to the unified stratigraphic series but are included into the structures of different-aged accretionary complexes. The terrigenous deposits of the Baldizhak series, as well as those of the Krestovka and Dzhalinda suites, probably belong to the accretionary complexes formed in front of the southeastern margin of the North-Asian craton. On the contrary, the sedimentary formations of the Preobrazhenovka suite are most likely constituents of the accretionary complex formed near the southern margin of the Amur superterrane. The absence of detrital zircons of Mesozoic age in the treated rocks allows one to assume that the considered accretionary complexes were formed during the Paleozoic. [ABSTRACT FROM AUTHOR]

U-Pb (LA-ICPMS) geochronological studies established the minimum age of detrital zircons from metasedimentary rocks of the Uril Formation of the Amur Group of ∼240 Ma, which approximately corresponds to the lower age boundary of formation of their protoliths. The upper boundary of accumulation of sedimentary rocks of this formation is governed by the age of superimposed structural-metamorphic transformations (220-210 Ma). It follows that the age of protoliths of metasedimentary rocks of the Uril Formation is Triassic in contrast to the previously suggested Early Precambrian age. At the same time, previous estimations of the Nd model age of metasedimentary rocks of the Tulovchikha Formation of the Amur Group and intruding gabbroic rocks are 1.7 and 0.5 Ga, respectively. In other words, the age of this formation is 1.7-0.5 Ga. All of this indicates a combination of sedimentary and volcanic rocks of different ages in the section of the Amur Group. Judging from the Lu-Hf isotopic-geochemical studies of zircons, the major sources of protoliths for metasedimentary rocks of the Uril Formation are Neoproterozoic igneous rocks and also Early and Late Paleozoic and Early Mesozoic igneous rocks, the formation of which was related to the reworking of the Neo- and Mesoproterozoic continental crust. [ABSTRACT FROM AUTHOR]

This paper presents the U-Pb zircon age of pulaskite of the main phase (294 ± 1 Ma) and the rare metal syenite (283 ± 8 Ma) of the Burpala alkaline pluton. The geochronological data show that it was formed in the Early Permian. By age, it is comparable with the Synnyr pluton of the Synnyr rift zone, alkaline granitic rocks and bimodal volcanic associations of the Uda-Vitim rift zone, and carbonatites of the Saizhen rift zone of the Central Asian foldbelt. These intraplate igneous complexes were formed almost simultaneously with crustal granitic rocks of the Angara-Vitim batholite. All of this gives ground to suppose that the origination of their parental melts is a result of the influence of the mantle hot spot or mantle plume on the lithosphere that led to extensive crustal anatexis. [ABSTRACT FROM AUTHOR]

The article presents information on a study conducted for determination of geochronology of deposition of zircons minerals in Timan Ridge, Russia. The isotopic investigation of the zircon minerals developed from terrigenous rocks in North Timan Ridges in Russia revealed that the rock has been formed in the Riphean geologic timescale. It mentions that the geologic age of the zircon minerals were analyzed through uranium-lead dating method. The study also revealed that the rocks in North Timan Ridges in Russia are largely composed of pelites, silt stones and sandstones.

The article presents information on a study conducted for determination of Paleozoic age relationships between brittle-plastic deformations and metamorphism within the Tseel metamorphic belt located in the southwestern part of Mongolian Altai mountains. It mentions that the geochronology of the successive stages of metamorphism of the mountain belt was analyzed by uranium-lead dating method by synmetamorphic granitoids and gabbroids. It highlights that chronology of stages of metamorphism and deformation plays important role in determination of history of the formation of accretional structures in Central Asia.

The article presents the findings of a study conducted on determining the age of rocks by geochronological methods. It focuses on Late Paleozoic Granitoid Magmatism within the geology which is represented by the Tyrma-Bureya multiphase gabbro-diorite-granodiorite-granite complex in most geological maps. A table which shows the result of Uranium-Lead geochronological studies for zircons from gneissic granites of the Sularin massif is presented. A graph is also presented which shows the relationship between zircon and gabbro from the Sularin massif granites.

The article presents a study which discusses uranium (U)-lead (Pb) geochronological dating of Paleozoic era granitoide rock formation of the Kiviliyskii complex in the Bureya Terrane in Russia. It says that porphyroblastic granites and rare quartz diorites from the Kiviliyskii massif were used as samples, in which accessory zircon crystals were selected and were subjected to multiple removal of surface contamination with ethanol, acetone, and nitric acid (HNO3). It says that Krogh's modified procedure was used for the chemical decomposition of zircon and U and Pb separation and isotope analyses were performed with the use of the MAT 261 multicollector mass spectrometer from Finnigan Corp. Results show that the granitoides in the site have an early Paleozoic era age.

The article presents a study on uranium-lead dating of protolith and paleoproterozoic tectonic and metamorphic transformations of the Archean Keivy terrain located in Kola Peninsula in Russia. It states that the Keivy terrain is composed of tonalite-trondhjemite association (TTG), Lebyazhinskaya Series and metavolcanic rocks, schists, and alkaline granites. It states that the age was estimated with the use of Sensitive High Resolution Ion Micropobe (SHRIMP) II, a secondary ion mass-spectrometer of high resolution, on zircons. It says that based of the uranium-lead dating, the age of the Keivy terrain is in the range of 1762-1721 million years (Ma).

This paper presents the results of Sm-Nd isotopic-geochemical and U-Pb geochronological studies of metamorphic (Ilikan Sequence) and associated igneous rocks from the Ilikan lithotectonic zone (terrane) located in the Dzhugdzhur-Stanovoi Superterrane from the Central Asian Foldbelt. The Nd model age, T(DM), of metamorphic rocks from the Ilikan Sequence is 2.6-3.2 Ga pointing to the likelihood that the lower boundary of their protolith formation probably does not exceed 2.6 Ga. The age of detrital zircons from metasedimentary rocks of the Ilikan Sequence is 2700-2900 Ma, which absolutely agrees with Sm-Nd isotopic-geochemical results. The U-Pb zircon age of metagabbro that intruded the rocks of the Ilikan Sequence and underwent high-temperature amphibolite metamophism with subsequent structural transformations is 2635 ± 4 Ma. The obtained results allow us to conclude that the age of the Ilikan Sequence is 2630-2700 Ma. All this gives grounds to state that the Dzhugdzhur-Stanovoi Superterrane in the Central Asian Foldbelt was formed due to amalgamation of non-Siberian terranes as is assumed for the Argun, Bureya, and Mamynskii terranes of the Amur Superterrane from the Central Asian Foldbelt. [ABSTRACT FROM AUTHOR]

The article discusses the acquisition of the megaannum (Ma) age values of zircons from the felsic volcanics of the Sumian section using the Uranium-Lead (U-Pb) sensitive high resolution ion microprobe (SHRIMP)-II ion method. It says that the obtained U-Pb ages were acquired for the intermediate and felsic composition dikes and that the zircon age analysis was conducted through the standard technique. It explores the classifications of the extracted zircons such as the one represented by bipyramidal crystals and one signified by long-prismatic crystals. It adds that the first group has an age value of 2423 ± 31 Ma while the second one has 2325 ± 10 Ma. It concludes that Karelian craton's Archean-Paleoproterozoic boundary should be placed at the Sumian Superhorizon base.