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The isotopic U–Pb ages are estimated for zircons (for the first time by the LA–ICP–MS method) from biotite (Eldzhurty) granites and for the first time from the rhyolites at the giant Tyrnyauz Mo–W deposit (North Caucasus). The weighted mean isotopic U–Pb age of zircon from the Eldzhurty granites is 2.10 ± 0.08 Ma, with variations from 1.78 to 2.53 Ma, whereas that of zircon from the rhyolites is 2.05 ± 0.04 Ma, with variations from 1.81 to 2.42 Ma. These data confirm the Neogene (Pleistocene) age of the rock crystallization, are in agreement with the emplacement sequence, and emphasize the short time span (~50 ky) between them.

The first data of a U–Pb isotopic study (LA-ICP-MS method) of zircon from leucocratic granites of the giant Tyrnyauz Mo–W deposit (North Caucasus) are presented. The emplacement of this granite separated the formation stages of Mo–W skarns and younger large stockworks with Mo-mineralization. Two types of zircons are distinguished among the grains identified. The first type is represented by rare tabular and short-prismatic crystals (xenocrysts) of an ancient zircon, with large variations of the U–Pb isotopic age (from about 300 Ma to almost 1500 Ma). The second type includes more abundant long-prismatic crystals of a young zircon; its weighted average U–Pb isotopic age (2.67 ± 0.04 Ma) corresponds to the time of leucocratic granite crystallization.

In order to determine the provenance and age of terrigenous-carbonate stratified units exposed in the region of Bagrush Mountains, Bashkirian uplift, U–Pb dating of detrital zircons from these units has been carried out. A comparison of the data results with analogous data on five stratigraphic levels within the Riphean section of the Bashkirian uplift has shown that the studied sequence should be, most likely, correlated to the uppermost Lower Riphean or the lowermost Middle Riphean.

Results of U–Th–Pb LA–ICP–MS analysis of detrital zircons from metasandstones of the Chiney Subgroup (Udokan Group, Aldan Shield) have been obtained. It has been revealed that rocks of the Paleoproterozoic (about 1.90, 1.98, and 2.50 Ga) and Neoarchean (2.55 and 2.72 Ga) were their provenance sources. Deposition of the Chiney Subgroup occurred in the interval 1.87–1.90 Ga and was separated in time from the accumulation of the Kodar Subgroup siliciclastics (2.1–2.3 Ga).

The results of LA–ICP–MS U–Pb analyses of detrital zircons from the Precambrian deposits of Luga–Ladoga monocline are discussed. The age spectra of the zircons separated from the Riphean to Upper Vendian sandstones from the Shotkusa-1 well demonstrate dominance of the Paleo- and Mesoproterozoic grains while the Archaean zircons are subordinate. The Riphean debris sources were local swells of the Northern Ladoga basement. The sequence interval presumably corresponding to the Vasilieostrov Formation (Upper Vendian) has yielded not only Paleo- and Mesoproterozoic zircon ages, but Neoproterozoic as well, implying a Timanide provenance: these zircons (527 ± 9 and 516 ± 13 Ma) allow deposition of a significant part of the Shotkusa-1 sequence at the very beginning of the Cambrian.

The results of U–Th–Pb geochronological study indicate that the youngest peaks on the relative probability curves of the age obtained for the Un’ya-Bom terrane correspond to ages of 207 and 212 Ma. These values were obtained for zircons from the meta-aleurolite samples from the Kurnal and Amkan formations, respectively. Similar age estimates for the youngest peaks were also obtained in the case of detrital zircons from the metasedimentary rocks of the Tukuringra terrane in the eastern part of the Mongol–Okhotsk fold belt, which indicates that, within the belt, Lower Mesozoic flyshoid complexes are much more widespread than was assumed. Based on the geochronological and Sm–Nd isotopic data obtained, it was shown that the material was carried to the sedimentation basin mainly from the continental massifs of the Amur superterrane.

The results of U–Pb dating of detrital zircons extracted from rocks of the Ai Formation are presented. A provenance-signal of a local source with an age of about 2.07 Ga has been documented, and the effect of the Ordovician magmatic episode on the sedimentary sequence has been revealed.

This report presents the results of U–Pb geochronological LA–ICP–MS studies of detrital zircons from metasedimentary rocks of the western part of the Tukuringra terrane. The obtained data show that the Algainskaya, Garmakanskaya, and Teploklyuchevskaya series in the western part of the Tukuringra terrane are not of Middle Paleozoic but of Early Mesozoic age. It is shown that the main sources of clastic matter for these formations were Late Precambrian, Paleozoic, and Late Triassic–Early Jurassic complexes of continental massifs of the Amur superterrane.

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.

The ages of detrital zircons from sandstones and silty sandstones from conditionally Upper Proterozoic–Cambrian rocks have been obtained for the first time. These deposits are united in the Khingan Group and are one of the most ancient formations in the Lesser Khingan terrane in the eastern part of the Central Asian fold belt. These data along with relationships with granitoids imply that the ages of the Muranda and underlying Igincha Formations range within the Tonian–Ediacaran time span, while the age of the Kimkan unit is Late Cambrian–Early Ordovician. Given that the Muranda and Igincha Formations, on the one hand, and the Kimkan unit, on the other hand, are substantially different in age and structurally separated by granitoids intruded at the Ediacaran–Cambrian boundary, we should accept that they cannot be regarded as a single sedimentary sequence.

Detrital zircons (DZs) from arkose sandstones of the Upper Riphean Zilmerdak Formation (Southern Urals) yielded ages in the range of 3039–964 Ma. Grains with Late Karelian and Early and Middle Riphean ages compose 35, 34, and 26% of the total number of the analyzed zircons, respectively. This is similar to the age spectra of the Vendian sandstones (Asha Group), but it differs significantly from the age distribution typical of the Riphean stratotype sandstones.

Geochemical Sm–Nd isotope and U–Th–Pb geochronological (LA-ICP-MS) studies have demonstrated that the Zeya Group of the Stanovoy Complex of the Dzhugdzhur–Stanovoy Superterrane (Central Asian fold belt) is not Paleoarchean, as was previously thought, but Paleoproterozoic in age.

The results of the LA-ICP-MS analysis of the concentrations of REEs, U, Th, and Hf in zircon from Paleo- and Neoarchean reference rocks of the Kola region (garnet–amphibole gneiss, basic and acid granulites, and granite pegmatite) are reported. A new methodology of the study of accessory zircons has been validated and modified. The accuracy of the results is confirmed by analysis of standard zircons Temora 1 and 91 500 and by comparison with the data obtained in other laboratories.

Here we present the results of U–Pb LA–ICP–MS dating of detrital zircons from the Ediacaran–Early Cambrian deposits of the eastern part of the Baltic monoclise (Leningrad Region). The obtained age spectra of the detrital zircons suggest that, in the Ediacaran–Early Cambrian, the main clastic material source to the northwest of the Russian Platform was the Baltic Shield. Then in the Early Cambrian along with the Baltic Shield provenance, a clastic source from the Timanian margin of Baltica (northeast in modern coordinates) contributed to the deposits. The obtained data either somewhat set limits of the Timanian orogen formation as older than the previously suggested Middle Cambrian (about 510 Ma), based on the “absence of a Proto–Uralian–Timanian provenance signal” in the Sablino Formation rocks in the south Ladoga, or suggest another rearrangement of detritus transportation paths at the end of Stage 3 (Atdabanian).

The Zelenodol porphyry Cu-(Au, Mo) deposit located about 65 km SSW of the city of Chelyabinsk is confined to the western part of the West Uralian Volcanogenic Megazone. The concordant U-Pb age of zircons from ore-bearing island-arc diorite porphyryis 418.3 Â ± 2.9 Ma.

The results of U–Pb geochronological studies of detrital zircons and Sm–Nd isotopic–geochemical studies of terrigenous rocks of the Upper Amur and Zeya–Dep troughs indicate that the beginning of orogenic processes, which led to the formation of the Mongol–Okhotsk fold belt, occurred in the Early Jurassic.

According to Sm-Nd isotopic-geochemical studies, the t Nd(DM) of the terrigenous rocks of the Turan Group of the Bureya terrane is 1.4–1.5 Ga and their sources are Precambrian rocks and (or) younger effusive rocks, the formation of which is related to the reworking of the Late Precambrian continental crust. The U-Pb LA-ICP-MS geochronological studies indicate dominant Vendian-Cambrian (588–483 Ma) and Late Riphean (865–737 Ma) detrital zircons. Our data point to their accumulation at the beginning of the Paleozoic rather than in the Precambrian as is accepted in modern stratigraphic schemes.

The results of studies indicate that the age of the protoliths of garnet-bearing biotite–sericite–muscovite schists of the Inim Block is

1200 In our previous communication [1], we presented geochronological data on detrital zircons (dZr) from sandstones of the Lemeza Subformation of the Karat� avian Zil’merdak Formation (standard of the Upper Riphean in northern Eurasia) developed in the Bash� kir Anticlinorium of the Southern Urals that borders the East European Platform (Fig. 1). From a total of 79 analyses, 66 qualified measurements yielded 206 Pb/ 207 Pb ages ranging from 3070 ± 27 to 1817 ± 59 Ma (Fig. 2a). The occurrence of two distinct differ�

This work is dedicated to the first results of zircon LA–ICP–MS U–Pb dating of the rocks from the granulite complex of the Khanka Massif in the Pri� morye region. Similar to the Khingan–Bureya (Rus� sia) and Jiamusi (China) terranes, the Khanka Massif (terrane) represents one of the principal structural ele�

Analyses of trace elements and Lu/Hf isotopes have been carried out in already U–Pb dated detrital zircons from the Upper Ordovician sandstones of the southern part of the Bashkir Uplift. The concentrations of trace elements in the zircons suggest that they were derived from rocks of intermediate (62%), basic (24%), and felsic (9%) compositions as well as alkaline rocks (2%). The Lu/Hf systematics of the zircons demonstrated a wide variation of both eHf (from +9.5 to–8.7) and model ages of the parental rocks (1.60 Ga < T DM C < 3.28 Ga). Comparison of the isotopic–geochemical characteristics of the detrital zircons from different levels of the Riphean–Paleozoic sequence of the Bashkir Uplift against those from the Early Cambrian Brusov Formation of the Mezen Basin and Early Neoproterozoic Dzhezhim sandstones of Timan Ridge suggests that at the end of the Late Precambrian near the Uralian margin of Baltica a large block of Late Mesoproterozoic–Early Neoproterozoic crust existed, comprising a significant proportion of melanocratic rocks.

This paper presents the results of selective study of trace elements (29 analyses) and the Lu/Hf isotopic system (41 analyses) in preliminarily dated (U-Pb) detrital zircons (dZrs) from sandstones of the Ai Formation of the Burzyan Group of the Bashkirian Anticlinorium, which compose the basal horizons of the typical Riphean section of the Southern Urals. The statistically processed trace-element patterns of dZrs showed that “diorites” were dominant over “syenites” among the source rocks of dZrs. The rock types estimated by trace-element patterns for the cores and rims of two large grains (“diorite” and “syenite”) coincided. The analysis of the Lu/Hf isotopic system of dZrs revealed a wide dispersion of the ɛHf value from +7.1 to −20.1 at the TDMC model age of the substrate from 2.25 to 3.95 Ga. Four grains (in one case with the core and rim studied) from the population of the large transparent cherry zircons (TCZ) are characterized by the “syenitic” rock type and extremely ancient TDMC values of 3.22, 3.45, 3.64, 3.66, and 3.75 Ga at ages of zircons of 2486, 2784, 2873, 1977, and 1984 Ma, respectively. Two “dioritic” grains from the TCZ population have significantly distinct parameters: 2.37 and 2.51 Ga at 2049 and 2057 Ma, respectively. It is evident that this specific population of dZrs was formed with a significant contribution of very ancient crustal material, which became active under “syenitic” magmatism and provided the TDMC value of >3.5 Ga. Numerous juvenile dZrs form a compact cluster, which correspond to the rocks of the southern part of the Volga-Sarmatian orogen (age of 2.1–2.0 Ga, TDMC = 2.1–2.4 Ga). The complexes of the entire the Volga-Uralia, the Volga-Sarmatian orogen, and adjacent areas could be the provenance areas for the Ai sandstones in contrast to the northeastern areas of the East-European Platform with dominant “granitic” source rocks and TDMC values lower than 3.5 Ga.

This work presents the first results of dating of detrital zircons (dZr s) from the Lower Paleozoic terrigenous-carbonate rocks of the Cambrian Blastertoppen (samples 08-137 and 08-142, south of the Wedel Jarlsberg Land) and Ordovician Wiederfjellet (sample K06-17, north of the Land) sequences, which are widespread to the north and south of the Hornsund Fjord, on the southwestern coast of Spitsbergen Island. Against the background of sporadic values of 1–3 Ga, samples K06-17 and 08-142 showed similar spectra of the age distribution of dZr s with dominant compact numerous age groups of ∼1.8–1.9 Ga and peaks of the maximum of the probability density of 1850 and 1862 Ma, respectively. The only noticeable difference in these spectra is the presence of a young grain of 541 Ma in sample 08-142 (with a very good value of concordance), which is close to the suggested Cambrian age of formation of the Blastertoppen sequence. The distribution of the dZr ages in sample 08-137 is significantly distinct. First, the general age range is narrower: 1.15–1.95 Ga (no Archean ages). Second, the age of 1.8–2.0 Ga dominant in the other two samples corresponds to only one grain. Thus, although samples 08-137 and 08-142 were taken from closely located levels of the section of the Cambrian Blastertoppen sequence (in the same interception), the age spectra of dZr s from these samples differ cardinally. The statistical Kolmogorov-Smirnov test quantitatively supports the visual similarity of age spectra of dZr s from samples K06-17 and 08-142 (p = 0.913) and the distinction of those from samples 08-142 and 08-137 (p = 0). Thus, the provenance areas, which supplied the clastic material to the sedimentary basin, whose remnants are presently located in the southwestern part of Spitsbergen, abruptly changed in the Cambrian. The basal levels of the Cambrian section of this basin (sample 08-137) were mostly formed due to accumulation of the erosion products of the local (Spitsbergen) sources: metarocks of the Eimfjellet Group located in the south of the Wedel Jarlsberg Land and of the Smerenburgfjord Group abundant on the Albert I Land. The dZr s age spectrum is a print of the ages of the Late Paleoproterozoic-Mesoproterozoic (pre-Grenville) basement unaffected by assemblage of Rodinia. Then the conditions changed and the basin became to accumulate the material from the remote regions, significant parts of which were the areas of ancient cratons, including Archean blocks. The general sedimentation conditions did not change considerably, because the rock type remained the same.

Attempts at dating detrital zircons from Late Pre� cambrian terrigenous rocks of the Western Urals have already been made. In (1-3), the age data of detrital zircons from Upper Middle-Upper Riphean and Lower and Upper Vendian (Upper Vendian-Middle Cambrian) deposits were summarized. This work pre� sents the first results of U-Pb LAICPMS isotope dating of detrital zircons, extracted from sandstones of the basal horizons of the Riphean stratotype sequence of the Southern Urals (Ai Formation, Burzyan Group of the Bashkir Meganticlinorium). The Bashkir meganticlinorium, a major structural unit of the structure of the Uralian foldthrust belt is located in the western segment of the Southern Urals (Fig. 1a). The Bashkir Meganticlinorium is composed of unevenly dislocated Paleozoic rocks. Within the Meganticlinorium, PreOrdovician complexes, divided distinctly into two units, are exposed on the surface. The lower horizons of these complexes are represented by Early Precambrian granitoides, amphibolites, and gneisses with relics of granulite� facies rocks (4, 5). This rock assemblage is referred to the Taratash metamorphic complex. In the northeast� ern part of the Bashkir Meganticlinorium, the Taratash complex composes the core of the Taratash Anticline. The rocks of the Taratash complex are over� lapped with stratigraphic and structural unconformity by a complex of terrigenous, terrigenouscarbonate, carbonate, and rarely volcanogenic and volcano� genic-sedimentary rocks with a total thickness of up to 12-15 km (4, 6, 7). The basal part of the complex is represented by conglomerates. The large lower part of this complex is the typical Riphean Erathem sequence (4, 6-8). The upper part is represented by the stratum of alternating aleurolites, sandstones, and rare arkose, and polymictic conglomerates (up to 1500 m thick) are referred as Upper Vendian (4, 7) or Upper Ven� dian-Middle Cambrian Asha (9).

The first data on the age of detrital zircons are given for Late Precambrian terrigenous rocks of the Baikal Group and Ushakovka Formation of the southern flank of the Siberian Craton. The ages obtained for 348 zircons cover the Paleoarchean to Late Ediacaran period, demonstrate the dynamics of change of sources of the clastic material in the sedimentation basin, and mark the changes of the Late Precambrian tectonic regimes. The age of the youngest group of detrital zircons extracted from the rocks of the Kachergat Formation allows us to restrict the upper age limit of accumulation of the rocks of the Baikal Group to the Late Ediacaran (Late Vendian).

The formation of granitoids of increased basicity and rocks of basitic composition on the Eastern slope of the Urals in the early Permian requires a reliable justification by geochronological data. U-Pb and Lu–Hf isotope systems in zircons separated from fine-grained granite of the Nepluyevsky pluton as well as Hf–Nd systematics of the rock were studied using LA-ICP-MS. Zircon LA-ICP-MS dating and the analysis of its Lu–Hf isotope system were performed using two mass spectrometers - quadrupole NexION 300S and multi-collector Neptune Plus and NWR 213 laser ablation system. The results of U-Pb dating for similar areas of NP-47 zircon grains by LA-ICP-MS and SHRIMP techniques are in satisfactory agreement. A difference in the age of zircons of different morphotypes was established: for the first type with a pronounced rhythmic zonation, a concordant U-Pb age was 360 ± 2 Ma (1σ, n = 19, SHRIMP- II) and 368 ± 6 Ma (1σ, n = 7, LA-ICP-MS); for the second type (“amoeboid-shaped” cores with “spotted” zoning), the concordant age was 430 ± 9 Ma (1σ, n = 1, SHRIMP-II). The comparison of the resulting isotopic Sm–Nd and Lu–Hf data suggests the xenogeneic, non-magmatic nature of the zircons contained in the rock, for which an older Silurian zircon of the second type could serve as a seed for growth. The age of the latter significantly exceeds the age of the Early Carboniferous rocks of the main phases of the pluton, broken by fine-grained granite.

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.

The first study on the distribution pattern and features of the “invisible” gold concentration in pyrite and arsenopyrite was carried out for a typical gold–quartz deposit of the Kolyma region. It was established that the main concentrator of “invisible” gold on the Pavlik deposit is the Late Arsenian pyrite-2. The method of Laser Ablation-Inductivity Coupled Plasma-Mass Spectrometer (LA-ICP-MS) gives an Au content up to 478 g/t; the Electron Microprobe Analysis (EMPA) gives up to 570 g/t by. The As content, determined by LA-ICP-MS is up to 4.1 wt % and up to 3.4 wt % by EMPA. Pyrite-2 overgrows and replaces the early pyrite-1 with a reduced content of As and Au. Microinclusions of the Pb–Zn–Cu–Sb–Ag–Bi–containing phases are concentrated at the boundaries of the pyrite-1 and pyrite-2 blocks. Pyrite-2 is depleted by an order in Cu, Zn, Ag, Sb, Pb, and Bi in comparison with pyrite-1. The max Au/As molar ratio in pyrite-2 is 0.006, which suggests the presence of Au in the form of a solid solution. In another case, pyrite, depleted by trace elements, is cemented with As, Ag, Sb, Au, and Pb-rich marcasite with native gold. In arsenopyrite, there is a homogeneous distribution of gold at low concentrations (up to 3 g/t) in euhedral crystals and a heterogeneous distribution (up to 7 g/t) in deformed fissured grains.

Mineralogical and geochemical studies of sulfide–platinum metal assemblages of the Khudolaz complex made it possible for the first time to substantiate their polygenetic nature. Three types of sulfide assemblages were distinguished. Their formation is associated with the segregation and fractionation of a sulfide melt, subsequent replacement of primary sulfides at the early hydrothermal stage, and partial redeposition of sulfides at the late hydrothermal stage. It was established (LA-ICP-MS data) that the removal of pla-tinum group elements (PGE) occurred due to primary sulfide alteration with their partial accumulation in newly formed sulfides. The structural position of PGM grains was studied using a scanning electron microscope. Platinum-group minerals (PGM) were crystallized during three stages: (1) from residual highly fractionated sulfide melts or immiscible metalloid melts captured by sulfides; (2) during the segregation of isomorphic impurities of PGE and chalcophile elements due to the exsolution of solid sulfide solutions; (3) during the interaction of antimony-enriched fluids with alternating sulfides.

The first results of U–Pb (LA–ICP–MS) isotope dating of detrital zircons (dZr) from the Upper Oligocene sands of the Poltava Formation exposed on the southeastern slope of the Voronezh anteclise are presented, providing information on the provenance sources. It is established that the dataset of dZr ages (provenance signal) is characterized by a predominance of ages within the range of 1–2 Ga with a low number of Phanerozoic, Late Proterozoic (younger than 1 Ga), and Archean dates. It is revealed that the cumulative ages of the complexes of the Svecofennian and Sveconorwegian orogens and, to a lesser degree, the Cadomides of Central Europe provide entirely the provenance signal recorded in the sands of the Poltava Formation. The data obtained allow us to refine the paleogeography of the Paratethys northern margin during the Late Oligocene. It has been found that the Poltava Formation was accumulated due to water transport of sediments from intensively eroded structures of western Fennoscandia from the North Sea to the Scythian Sea.

This work presents the results of U–Th–Pb (LA–ICP–MS) geochronological study of detrital zircons from terrigenous deposits of the Olokit zone of the Baikal–Patom fold–thrust belt of the Siberian Craton. It was established that the age of deposits of the Olokit Formation is in the range of 0.86–0.72 Ga. Archean and Early Proterozoic rocks of the southern part of the Siberian Craton and the Neoproterozoic complexes of the Baikal–Muya belt were the sources of detrital zircons of the terrigenous rocks of the Olokit zone. There is no evidence of rocks that could have been the sources of Mesoproterozoic (1.08–1.46 Ga) and Late Paleoproterozoic (1.65 Ga) detrital zircons for the deposits of the Ondok paleo-uplift in the Olokit zone, in the Baikal mountain region, and in the Siberian Craton. The data obtained and the results of paleomagnetic reconstructions indicate that Siberia and Laurentia in the Meso- and Early Neoproterozoic were in a fixed position relative to each other; an unknown continental block composed of Mesoproterozoic rocks could have occupied the space between them.

The first U–Pb (LA–ICP–MS) isotope dating of detrital zircons from quartzites of two strata of the Maksyutov metamorphic complex (Southern Urals) was performed. Zircon grains from the Galeevo quartzites are well rounded. The concordant zircon ages fall into the ranges of 529–594, 956–2144, and 2709–2781 Ma; the main age peaks are 544, 551, and 1491 Ma. Zircon grains from the Yumaguzino quartzites are idiomorphic and weakly rounded. The concordant zircon ages fall into the ranges of 497–640 and 957–1027 Ma, forming distinct age peaks of 514, 548, and 605 Ma. The U–Pb ages obtained and their comparison with similar data on the other sequences of the Southern Urals and the Caspian Sea Region indicate the Ordovician age of the protolith of the studied quartzites of the Maksyutov complex.

The results of U–Pb isotope dating of perovskites from silicate–calcite vein rocks spatially associated with the Kusa–Kopan gabbro intrusion are presented. At present, the genesis of these silicate–carbonate rocks remains controversial. The obtained U–Pb ages are 497.0 ± 4 Ma for perovskite from the Perovskite mines and 468 ± 6.4 Ma for that from the Zelentsovskaya mine. The obtained ages are significantly different from the age of the Kusa–Kopan gabbro intrusion (1379 ± 8 Ma). Furthermore, the REE distribution trend (LA–ICP–MS) in the perovskites studied is similar to that in perovskites from carbonatites and kimberlites. Together with the geochronological data, this suggests that the carbonate–silicate rocks studied originated from a carbonatite origin. Additional confirmation of the manifestation of Early Paleozoic diastrophism in the region studied is the U–Pb age of zircons from volcanics of the Bashkir anticlinorium obtained earlier by various methods.

The results of U–Th–Pb LA-ICP-MS dating of detrital zircons collected from the Permian–Triassic red beds of the Moscow Basin are presented. U–Th–Pb ages of detrital zircons from two samples (Upper Permian and Lower Triassic), which were collected in the vicinity of the P–T boundary in the Zhukov Ravine reference section, show their contrasting provenance. It means that U–Pb detrital zircon geochronology can be used as an additional independent tool for stratigraphic correlation of the Permian–Triassic red beds, at least within the Moscow Basin. The applicability of the method is illustrated by additional constraints on the age of the Nedubrovo member deposits (Vologda Region) with a previously uncertain stratigraphic position: the U–Pb age pattern of the respective detrital zircons suggests their Early Triassic age.

LA-ICP-MS U–Pb dating of detrital zircons reveals two levels of accumulation of Proterozoic quartzites in the Kyrgyz North Tianshan. The quartzites of the Makbal Formation in the core of the Makbal anticlinorium have a maximum depositional age of 1.7 Ga and characterize the oldest stage of accumulation of quartzites in the western Central Asian Orogenic Belt. Quartzites of the Ovva Formation in the northeastern limb of the Makbal anticlinorium and Djeldysu Formation in the Burkhan anticlinorium have maximum depositional ages of ca. 1.0 Ga. Distributions of detrital zircon ages in these two formations are identical and indistinguishable from detrital zircon age distributions in the Neoproterozoic quartzites of the North Kazakhstan. The latter three quartzitic units have common provenance and, apparently, represent the same stratigraphic level. Distinctly different distributions of detrital zircon ages indicate that Precambrian microcontinents of the Kokchetav-North Tianshan zone represented independent continental massif with respect to Precambrian crustal blocks of the Middle Tianshan and Tarim Craton.

New data are presented on the quartz porphyry dikes of the Salmi batholith belonging to anorthosite–rapakivi granite rock complexes. The relationships of various igneous rocks of the Salmi batholith and metasomatites were determined along with the isotopic U–Pb age by the LA–ICP–MS technique and the temperature of zircon formation by the Ti content.

The U–Pb age and oxygen and hafnium isotope ratios of zircon from rocks of oceanic core complexes along the Mid-Atlantic Ridge have been studied using SHRIMP and MC-LA-ICP-MS techniques. The U–Pb dating revealed four groups of zircon: (1) 0.6–1.7 Ma, (2) 6.7–11.2 Ma, (3) 12.9–17.6 Ma, and (4) ≥ 200 to 2044 Ma. The δ18O values range from 4.74 to 7.2‰ and are distinct for zircon grains of different ages. The hafnium isotope ratio for zircon with an age from 0.6 to 17.6 Ma corresponds or is close to that of the MORB from the Central Atlantic. The oxygen and hafnium isotope compositions of zircon older than 280 Ma correspond to those of the sialic continental crust. The hypothesis of involvement of the ancient “pre-Atlantic” sialic (≥280 Ma) and “old Atlantic” (7–17 Ma) crusts in the generation of the contemporary (“juvenile”) oceanic crust during the formation of the slow-spreading Mid-Atlantic Ridge has been proposed.

The Egdygkych hypabyssal rocks of the Nichan and Vuknei massifs, as well as the host volcanites and tuffs of the Oloi volcanic belt of the Alazeya–Oloi folded system have been dated by U–Pb (SIMS and LA–ICP–MS). The obtained ages of the Egdygkych complex correspond to the Early Cretaceous (Berriasian–Valanginian), while those of their host rocks range from the Late Jurassic (Tithonian) to the beginning of the Early Cretaceous (Berriasian). These new U–Pb geochronological data confidently suggest a unity of the volcanic–plutonic association of the Late Jurassic (Tithonian)–Early Cretaceous (Berriasian–Valanginian) age of the Oloi volcanic belt. The data obtained refine the age range of Au–Mo–Cu ores confined to the contacts between the Egdygkych complex rocks and host volcano-sedimentary deposits or contacts of individual intrusive phases within the complex.