—The paper presents new data on the Rauer Islands, one of the unique objects of the East Antarctic Shield. The interest in this area is triggered by its complex geologic structure, including both Archean and Proterozoic fragments of the Earth’s crust, and by its multiphase formation. A detailed scheme of the geologic structure of the area is proposed, new petrologic complexes are revealed, and the stages of tectonomagmatic activity at ~1400–1320 Ma and 1150 Ma are reliably dated. This serves as a factual basis for comparison the study area with other regions of East Antarctica. Based on the geological and isotope data obtained, the Meso–Neoproterozoic Filla Terrane in the area of the Rauer Islands is recognized. It is composed of metamorphic and primarily intrusive rocks, whose protoliths formed in the time interval 1400–950 Ma. Three periods of tectonothermal activity have been established in the Filla Terrane: Mid-Mesoproterozoic (1400–1320 Ma), Meso–Neoproterozoic (1150–886 Ma), and early Cambrian (536–504 Ma). The first period is the formation time of Mesoproterozoic crust, and it is time-correlated with the tectonogenesis phase in the adjacent Rayner province. The second period corresponds to the later phase of tectonothermal activity in the Rayner province. In the Filla Terrane, this period can be divided into two intervals, 1150–1100 Ma and 1010–886 Ma. The former interval is treated as intense crustal growth in the course of granitoid and mantle magmatism. The latter interval is a period of tectonothermal processes accompanied by intense deformations, high-temperature metamorphism, and intrusion of porphyritic granitoids. Apparently, the gap between the first and the second intervals is the time of deposition of the sedimentary protolith of paragneisses, which, together with the surrounding rocks, underwent high-temperature metamorphism and deformations at 950–914 Ma. The synchronous evolution of the Archean block and the Filla Terrane began at least within 1100–1000 Ma. The youngest, early Cambrian period of tectonic activity coincides with the development of local low-temperature mylonite zones and the intrusion of synkinematic pegmatite veins. Thus, the tectonothermal evolution of the Filla Terrane includes almost the same main phases of crustal growth and transformation as the Rayner province. This indicates that the Filla Terrane is a fragment of the Rayner province, which accreted to the Archean terrane at least in the late Mesoproterozoic.

The Sandow Group in the Denman Glacier area consists of low-grade supracrustal (post-cratonic) strata. Such rocks are scarce and poorly studied in East Antarctica, but are significant for a better understanding of the geological history and tectonic evolution of the Precambrian supercontinents. We report U-Pb (LA-ICP-MS) detrital zircon ages which mostly fall into two groups of ca 1350 900 Ma and ca 1800 1500 Ma, which correspond to those of crystalline rocks exposed in the western Australo-Antarctica. The youngest zircons with magmatic zoning yield ages of ca 950-900 Ma which define the maximum age of sedimentation. Chemical and neodymium isotopic compositions of the Sandow Group rocks indicate derivation from a Proterozoic largely granitic source region. High-Ti mafic volcanic activity accompanied sedimentation, and therefore the Sandow Group should be considered a volcanic-sedimentary succession. The Sandow Group was presumably accumulated in a continental (pull-apart?) basin formed in the Neoproterozoic in relation to proto-Darling Fault system activity with its continuation into Antarctica. The Sandow Group may have its correlatives in Western Australia where sedimentary successions (e.g., Moora and Badgeradda Groups) occur along the proto-Darling Fault system.

The work presents the results of a study on Lu-Hf systematization of zircons from rocks of the Shamanic ultramafic massif, which is part of the Baikal-Muya ophiolite belt. It is composed to varying degrees of serpentinized and dynamometamorphized harzburgites and dunites subordinate to them, which have a restitogenic nature. From a composite sample of these rocks weighing about 4 kg, 31 zircon grains 100-150 mu m in size were extracted and sold by U-Pb. All these grains had a rounded shape and a rough surface. Most of them are characterized by a very low to complete absence of cathodoluminescent light intensity. According to the values of the isotopic age, the entire collection of zircons was divided into three clusters: a) "ancient" (3,049-1,189 Ma); b) "intermediate" (827-812 Ma); c) "young" (630-502 Ma). In representative mineral grains from these clusters, the parameters of their Lu-Hf isotopic systems were determined. Zircons from the "ancient" cluster are characterized by increased values of the parameter (PbPb)-Pb-207-Pb-/ 206, as well as lower values of the parameters Th-232/U-238, Yb-176/Hf-177, Lu-176/Hf-177 and Hf-176/Hf-17(7). Zircons from the "intermediate" cluster are characterized by increased values of the parameter Th-232/U-238, lower values of the parameter Yb-176/Hf-177, as well as intermediate values of the parameters Lu-176/Hf-177 and Hf-176/Hf-177. Zircons from the "young" cluster are characterized by intermediate values of the parameter 232Th/ 238U, approximately the same as in the previous cluster, by the values of the parameter Yb-176/Hf-177, and also by increased average values of the parameters Lu-176/Hf-177 and Hf-176/Hf-177. The studied zircons are considered as a relic phase. It is assumed that initially the few grains of this mineral were in the form of a juvenile phase in the composition of the upper mantle protolith, whose age exceeded 3,000 million years. It is also assumed that subsequently, during the heating and partial melting of protolith, which initiated the diffusion of Pb and U ions in the structure of juvenile zircons, disturbances occurred in their U-Pb and Lu-Hf isotopic systems, which caused the observed uneven "rejuvenation" of their age.

Приводятся результаты изотопных исследований первично магматических и осадочных пород серий Моусон и Мензис, распространённых в южной части гор Принс Чарльз, Восточная Антарктида. Полученные данные показывают, что кристаллизация магматического протолита ортогнейсов серии Моусон произошла 3164,2±9,2-3163,2±7,8 млн лет назад. Ортогнейсы серии Моусон являлись фундаментом, на котором откладывались осадочные породы серии Мензис, а максимальное время их седиментации составляет 3,0-3,1 млрд лет. Протолит осадочных пород содержит примесь вещества палеоархейского возраста.

The discussed below results on Pb isotopic compositions have been obtained by both TIMS and LA-ICP-MS-MC techniques on sulphide and plagioclase mg-weight specimens and single grains correspondingly. General Pb isotopic compositions imply derivation from both, the mantle and crustal sources with the latter being dominant. The obtained results from the Talnakh intrusion notably discrepant from that of the Norilsk and Kharaelakh being less radiogenic, while the latter two cluster together, demonstrating a minor divergence between massive and disseminated ores. Analysis of Pb-207/Pb-204 versus delta S-34 along with Th/U assumes three sources of mantle, lower curst and upper crust, while Pb isotopes alone do not provide distinguishing of the massive ores from poor one. Disparity of Pb isotopes in sulphides and plagioclases assumes their chemical and isotopic disequilibrium, precluding their coexistence in a single batch of melt.

The chapter describes a technique of analysing copper and nickel isotopes in ores and magmatic rocks of deposits. Average delta Cu-65 value strongly diverges in rich intrusions: Kharaelakh (-1.55 parts per thousand), Talnakh (-0.7 parts per thousand), and Norilsk-1 (+0.25 parts per thousand). Perhaps this is due to the mixing of the crustal and mantle sources of matter in the formation of these massifs. The Kharaelakh intrusion by delta Cu-65 has a large share of crustal matter. In the remaining massifs, the average value of delta Cu-65 is almost the same (-0.8 to -0.3 parts per thousand) and does not correlate with the isotope composition of sulphur. The average values of nickel Ni-61/Ni-60 isotope composition vary within narrow limits from -0.6 to 0 parts per thousand in all intrusions of the region and point to a single source of this metal. Data on copper and nickel isotopes in the products of mining and metallurgical companies in the world are given. Variations in the isotopic composition of copper are more associated with raw materials sources of companies, and the isotope composition of nickel, with different technological processes. A possible change in the isotopic composition of nickel during carbonylation (a mond process) is considered.

Lu-Hf isotope is an informative geochemical tool. Comprehensive in situ study of U-Pb and Lu-Hf isotope systems in zirconium minerals (zircon, baddeleyite) by LA-ICP-MS allows obtaining characteristics of the initial substance and evolution of the earth's crust. The data bear the crucial important information about the parent rocks and ore source in the Norilsk-Taymyr district. This chapter presents data obtained in VSEGEI isotope laboratory and in Australia. In Norilsk ores, significant variations in Hf isotopic composition have been revealed. Zircons of commercially ore-bearing intrusions have an increased value of epsilon Hf (to +10, weighted average epsilon Hf(T) = 8.2 +/- 1.8). Compared with them, the Lower Talnakh low ore-bearing intrusion has practically zero eHf values. Thus, according to the results of the studied zircon sample, we can say that high eHf values are a necessary isotope criterion of ore content.

—The paper presents the geochemical and isotope characteristics of rocks and the U–Pb age and Lu–Hf isotope composition of zircons from three plutons of Paleoproterozoic granitoids in the Sharyzhalgai uplift (southwestern Siberian craton). The age of granitoids of the Toisuk (1838 ± 6 and 1827 ± 9 Ma), Nizhnii Kitoi (1846 ± 7 Ma), and Malaya Belaya (1863 ± 16 Ma) plutons corresponds to the Late Paleoproterozoic collision stage and is correlated with the time of mafic magmatism. The studied rocks have a wide range of silica contents. The Toisuk pluton is composed of a range of rocks from monzodiorites to granodiorites (granosyenites) and granites; the Nizhnii Kitoi pluton, of granodiorites and granites; and the Malaya Belaya pluton, of leucogranites. The rocks of the three plutons are highly ferroan, enriched in LREE, Th, and HFSE, and correspond in composition to A-type granitoids. A characteristic feature of melanocratic granitoids of the Toisuk and Nizhnii Kitoi plutons is extremely high contents of Ba: 4080–1500 ppm and 1560–990 ppm, respectively. Based on analysis of experimental data on the melting of various substrates and the results of numerical simulation, it is assumed that monzodiorite–granodiorites of the Toisuk pluton and granodiorites of the Nizhnii Kitoi pluton resulted from the differentiation/melting of a mafic source similar in Ba and Sr contents to intraplate continental basalts. The isotope compositions of zircon and melanocratic granitoids of the Toisuk (εHf from –6.0 to –10.7 and εNd from –5.3 to –10.2) and Nizhnii Kitoi (εHf from –5.0 to –8.1 and εNd = –4.0 and –5.1) plutons argue for the generation of their mafic sources from the enriched lithospheric mantle formed as a result of Neoarchean subduction processes. Vein granites of the Toisuk pluton and leucogranites of the Malaya Belaya pluton formed through the melting of quartz–feldspar (granodiorite) substrate. The contrasting isotope parameters of the Toisuk vein granites (εHf from –6.7 to –10.1, zircons, and εNd = –5.5, rock) and Malaya Belaya leucogranites (εHf from 2.9 to 5.9, zircons, and εNd from +0.7 to –1.9, rocks) indicate melting of the Archean and Paleoproterozoic crust, respectively. The more radiogenic Hf isotope composition of zircons from vein granites as compared with rocks of the Archean crust of the Irkut terrane is evident of the contribution of juvenile material to the granite formation.

Paper presents results of isotope studies of primary igneous and sedimentary rocks of Mawson and Menzies series from the southern Prince Charles Mountains, East Antarctica. Obtained data show that igneous protholith crystallization of Mawson orthogneiss occurred at 3164,2±9,2-3163,2±7,8 Ma ago. The Mawson orthogneiss were a basement for Menzies series sediment. The maximum time of sediment deposition is estimated to be in the range of 3,0-3,1 Ga. Sediment protholith involves an admixture of Paleoarchean material.

Results of this study of titanite samples collected from silicate rocks and apatite-nepheline-(sphene) ores from Paleozoic polyphase alkaline nepheline syenite complexes of the Khibiny and Lovozero massifs revealed the possibility of their in-situ U-Pb dating using sensitive high-resolution ion microprobe SHRIMP-II with an accuracy of 1.0-1.5%, which is comparable with that of U-Pb zircon analysis. Employing different approaches to age determination of the formation of the U-Pb system of titanites, the combined isochrons and mixing lines were plotted from the data obtained from the differentiated complex samples (121 analyses of five Khibiny samples and 52 analyses of one Lovozero sample) and apatite-nepheline ores (120 analyses of five Khibiny samples and 88 analyses of three Lovozero samples). They indicate synchronous crystallization of titanite in silicate rocks throughout the complexes: 374.1 +/- 3.7 Ma for the Khibiny massif and 380.9 +/- 4.5 Ma for the Lovozero massif, and attest to the later formation of phosphate-rare-metal ores: 371.0 +/- 4.2 and 361.4 +/- 3.2 Ma, respectively. The relatively delayed ore mineralization specific to the Lovozero massif can be accounted for the significantly lower volumes of magmatic melt and ore fluid involved, different thermal conditions, and the pattern of the investigated mineralization. As such, the obtained U-Pb data from titanite make it possible to limit significantly the time interval (most likely, not exceeding 15-20 Ma) comprising the evolution and activity of the ore-magmatic system of major agpaitic complexes, which is probably associated with plume magmatism. (C) 2018, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others.

This report presents data on the geological structure and location of the orthopyroxenite inclusion in gneissic enderbites of the Bug granulite–gneiss domain. Three stages of orthopyroxenite formation were identified on the basis of studies of the mineral composition along with the U–Pb and Lu–Hf isotope systems of zircons.

We present geochemical characteristics of rocks and results of local dating and Lu-Hf isotopic analysis of zircons from two plutons of Paleoproterozoic collisional granitoids in the northwest of the Sharyzhalgai uplift. The rocks of the Alar pluton in the Bulun terrane correspond in major- and trace-element composition to I-type potassic granites. The Alar granites formed at similar to 780 C and <5-8 kbar through melting of predominantly graywacke (volcanosedimentary) source rocks with the contribution of melt from plagiogneisses of tonalite-trondhjemite complex. The age and Lu-Hf isotopic similarity between inherited zircon core (3.3-3.0 and 2.85-2.6 Ga) in these granites and zircons from the Paleo- and Mesoarchean rocks of the Bulun terrane suggests that the latter are the most likely crustal sources of the granites. The more radiogenic isotope composition of the Paleoproterozoic (1.85 Ga) magmatic zircons from the granites as compared with the Archean crustal rocks of the Bulun terrane testifies to the contribution of juvenile material to the granite formation. Highly ferroan granodiorites and granites of the Shumikha pluton in the Onot terrane are enriched in HFSE and correspond to A-type granites. They probably derived by the melting of crustal sources of intermediate-felsic (tonalitic) and mafic composition at >= 860 C. The Hf isotope composition of magmatic (1.86 Ga) and inherited (ca. 2.5 Ga) zircons indicates that the granites formed from ancient crustal source (model Hf age is > 3.0 Ga) with the contribution of Neoarchean juvenile, probably mafic material. (C) 2017, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

Химический и Os-изотопный состав минеральных ассоциаций платиноидов конгломератной формации Кимберли (Витватерсрандский бассейн, Южная Африка) И. Ю. Баданина, К

Multidisciplinary studies of zircons, rock-forming minerals and the whole-rock composition of granulite samples from the Bug Granulite-Gneiss Complex, Ukraine (including ion microprobe REE analysis, secondary ion mass spectrometry (SIMS) U-Pb and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) Lu-Hf analysis of zircons from a single sample) have revealed three major stages in the geological evolution of the complex. (i) At 3.66 Ga, a mafic intrusion contaminated with felsic rocks formed, as evidenced by 3.74 Ga zircon xenocrysts with inclusions of plagioclase, K-feldspar and quartz. (ii) At 3.59-3.55 Ga, high-temperature and high-to moderate-pressure granulite-facies metamorphism accompanied by migmatization and deformation resulted in the formation of mafic granulites. (iii) At 2.12.0 Ga, metamorphic overprinting occurred, and metatrachybasaltic dykes intruded at approximately 2.0 Ga. The metamorphic mineral assemblages recorded in the dykes formed at temperatures similar to those of the 3.59-3.55 Ga metamorphism but at pressures 2-3 kbar lower. This metamorphism disturbed the Sm-Nd whole-rock system, altered the Hf isotope system of the older zircons and resulted in Pb loss in small zircon grains. This complex event history recorded in zircons from a single rock corresponds to major stages of the geological evolution of both the Dniester-Bug Province and the entire Ukrainian Shield.

We firstly report compositional and isotope-geochemical characteristics of Ru-Os-Ir(-Pt) alloys, Ru-Os sulfides and polycomponent solid solutions of the system Ru-Os-Ir-Pt (±Fe) derived from the Kimberley Reef within Evander Goldfield of the Witwatersrand Basin (South Africa). The study employed electron microprobe analysis and laser ablation attached to multiple collector inductively coupled plasma mass spectrometry. The obtained results are consistent with: 1) high-temperature formation of the studied platinum-group minerals, 2) sub- hondritic Archean source of platinum-group elements, 3) similarity of the initial Os-isotope composition in coexisting Os-rich alloys and Ru-Os sulfides and 4) significant Os-isotope variations in individual Ru-Os-Ir alloys, Ru-Os sulfides and polycomponent solid solutions of the Ru-Os-Ir-Pt (±Fe) system. 187Os/188Os ages are used to discriminate between different models of noble metal mineralization origin within the Witwatersrand basin.

We firstly report compositional and isotope-geochemical characteristics of Ru-Os-Ir(-Pt) alloys, Ru-Os sulfides and polycomponent solid solutions of the system Ru-Os-Ir-Pt (±Fe) derived from the Kimberley Reef within Evander Goldfield of the Witwatersrand Basin (South Africa). The study employed electron microprobe analysis and laser ablation attached to multiple collector inductively coupled plasma mass spectrometry. The obtained results are consistent with: 1) high-temperature formation of the studied platinum-group minerals, 2) sub- hondritic Archean source of platinum-group elements, 3) similarity of the initial Os-isotope composition in coexisting Os-rich alloys and Ru-Os sulfides and 4) significant Os-isotope variations in individual Ru-Os-Ir alloys, Ru-Os sulfides and polycomponent solid solutions of the Ru-Os-Ir-Pt (±Fe) system. 187Os/188Os ages are used to discriminate between different models of noble metal mineralization origin within the Witwatersrand basin.

This study was carried out to determine the initial age and time-span of interaction of two major crustal provinces of Asia: the Siberian craton and the Central Asian Orogenic Belt (CAOB). Single grain U-Pb ages of detrital zircon suites from the Neoproterozoic passive margin strata of the Siberian craton were used to determine the first appearance of extraregional source regions. Twelve Neoproterozoic clastic rocks from the Baikal-Patom margin of Siberia and one sample from the volcaniclastic Padrinsky Group that was deposited unconformably above accreted CAOB crust were analyzed. In total, 1152 grains were analyzed, 703 were used for provenance interpretation. Stratigraphically lower strata from the Siberian margin yield Archean - Paleoproterozoic detrital zircon ages, which are similar to, and probably derived from the Siberian Precambrian craton. A few extra-regional Mesoproterozoic grains are also present.The provenance shift happens in the upper portion of the section and is marked by the influx of extraregional zircons. The youngest included zircons (610 Ma) constrain the age of deposition and provide evidence for the timing of initial interaction between CAOB and Siberia in this region. Neoproterozoic zircons also dominate the overlying sedimentary units of the CAOB, suggesting continuing convergence. Coeval volcaniclastic unit deposited across the accreted CAOB terrane has a similar U-Pb detrital zircon age distribution, strengthening the provenance links between the two sides of the orogen.Analysis of the local tectonics suggests that the beginning of accretion might have started even before the first appearance of Neoproterozoic zircon: during the development of a regional unconformity, capped by 635 Ma (?) "Snowball Earth" tillites of Dzhemkukan Formation. The absence of Neoproterozoic zircons in Dzhemkukan Formation is probably explained by the absence of development of an extremely thickened crust.Our data are in good agreement with data collected from other Neoproterozoic sedimentary basins of southern Siberian craton, including Cisbaikalia and Bodaibo Synclinorium. (C) 2015 Elsevier B.V. All rights reserved.