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Journal of Earth Science 2024年

作者： Tatiana Osipova Gennadiy Kallistov Maria Chervyakovskaya Vasiliy Chervyakovskiy Zavaritsky institute of geology and Geochemistry，Ural Branch of ras

Field- and petrographic investigations， together with microanalytical major- and trace-element studies， were carried out on clinopyroxene and amphibole from high-Mg diorite in the subduction-related Chelyabinsk granitic massif to understand its petrogenesis and source. The clinopyroxene composition (high Mg#， Cr-content， sum of REE and Ti/Eu ratio; depletion in HREE; negative Eu-anomaly) indicates that it formed from a reduced melt derived from a mantle source metasomatized by fluids/melts having crustal affinity. Melt compositions in equilibrium with clinopyroxene and amphibole were calculated using solid/liquid partition coefficients. The high Nb/Y and Zr/Y ratio values of a liquid simulated from clinopyroxene， which appears to have very similar characteristics to sanukitoid melts， indicate a low degree of melting of the mantle source. Melt simulated from amphibole is more evolved and more felsic (dacitic). It displays a geochemical “amphibole fractionation” signature， indicating the peritectic transformation of clinopyroxene to amphibole in the lower crust. Rock textures and major element mineral compositions suggest that further amphibole was precipitated directly from the melt in the middle crust. The results show that the Chelyabinsk high-Mg diorite was probably formed as a cumulate from sanukitoid-like melt during its ascent and cooling below dacitic liquidus inside the amphibole stability field.

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Age and geochemical evolution of granite magmatism in Olkhon region from Caledonian syncollisional ore-free granite to the rare metal granite and pegmatite of Middle Paleozoic intraplate setting

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China geology 2024年第1期7卷 63-79页

作者： Viktor Antipin Valentina Makrygina Larisa Kushch Nataliya Sheptyakova Vinogradov institute of Geochemistry SB RAS664033 IrkutskRussia

The detailed description of two granite complexes in the Olkhon subterrane is *** Early Paleozoic Sharanur complex was formed by granitization of gneisses of the Olkhon *** includes migmatites,granite-gneisses,granites and pegmatites of normal alkalinity;they belong to the type of syncollisional *** Middle Paleozoic Aya granite complex includes mother Aya massif of amazonite-bearing granites and several types of rare-metal *** have elevated alkalinity,low of Ba,Sr,and high LILE and HFSE elements *** Aya pegmatites lie in northwest cracks of stretching and associated with the rise of the territory under the influence of the North Asian *** cracks and pegmatites mark the beginning of a new intraplate geodynamic *** geochemical types are distinguished among the pegmatites of this *** are amazonite pegmatites of Li-F type with Ta mineralization and complex type pegmatite with Be-Rb-Nb-Ta and Li-F mineralization(the Ilixin vein).The Tashkiney pegmatite vein is similar to Ilixin,but lies in the gneisses of the Olkhon *** shows high concentrations of Be,Nb,Ta,as well as W,Sn,but lacks Li and F,due to a greater depth and higher temperature of the melt crystallization of this pegmatite.

关键词： Pegmatite Geochemistry Submantle plume Magmatism Caledonian collision Middle Paleozoic intraplate setting Be-Rb-Nb-Ta-Li-F mineralization Olkhon region Russia

Sr-Isotopic Characteristic of the Typical Carbonate Neoproterozoic Siberia Sections

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地学前缘 2009年第S1期16卷 194-195页

作者： Vishnevskaya Irine Kuznetsov Anton Letnikova Elena institute of geology and Mineralogy SB ras institute of precambrian geology and geochronology ras

First Sr isotopic data for the type of Neoproterozoic carbonate sediments of the South Siberia are reported. Upper Riphean complex is represented by terrigenous -carbonate rocks of Tungysic Formation,Yenisey Mountain *** age of this Formation shows a wide range,from 924±40 Ma(K-Ar method)to 753±6 Ma(U-Pb method).Sediments of Zabit Formation,Bokson Series(East Sayan)and

关键词： Neoproterozoic carbonate sediments Sr isotopic chemostratigraphy

Early Neoproterozoic Granite-Gneisses of the Junggar Alataw(Southeastern Kazakhstan):Age,Petrogenesis and Tectonic Implications

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 67-82页

作者： Nadezhda KANYGINA Andrey TRETYAKOV Dmitriy ALEXEIEV Kirill DEGTYAREV Anfisa SKOBLENKO Natalia SOLOSHENKO Boris ERMOLAEV Geological institute Russian Academy of SciencesMoscow 119017Russia A.N.Zavaritsky institute of geology and Geochemistry Ural Branch of the Russian Academy of SciencesYekaterinburg 620016Russia

The combined petrographic,petrological,geochemical and geochronological study of the Neoproterozoic gneisses of the Sarychabyn and Baskan complexes of the Junggar Alataw of South Kazakhstan elucidate the precambrian tectonic evolution of the Aktau–Yili *** is one of the largest precambrian crustal blocks in the western Central Asian orogenic *** U-Pb single-grain zircon ages indicate that granite-gneisses formed from the same source and crystallised in the early Neoproterozoic ca.930–920 *** chemical composition of gneisses corresponds to A2-type *** whole-rock Nd isotopic characteristics(εNd(t)=−4.9 to−1.0 and TNd(DM-2st)=1.9 to 1.7 Ga)indicate the involvement of Paleoproterozoic crustal rocks in magma *** Neoproterozoic ca.930–920 Ma A-type granitoids in the Aktau–Yili terrane of South and Central Kazakhstan might reflect within-plate magmatism adjacent to the collisional belt or a local extension setting in back-arc areas of the continental arc.

关键词： granitoid magmatism geochemistry geochronology Sm-Nd isotope systematics Neoproterozoic Junggar Alataw Kazakhstan Central Asian orogenic belt

Tourmalinization at the Darasun goldfield,Eastern Transbaikalia:Compositional,fluid inclusion and isotopic constraints

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Geoscience Frontiers 2012年第1期3卷 59-71页

作者： Vsevolod Prokofiev Ivan Baksheev Lidiya Zorina Boris Belyatsky Vladimir Ustinov Nadezhda Krivitskaya institute of geology of Ore Deposits Petrography Mineralogy & GeochemistryRussian Academy of SciencesMoscowRussia Lomonosov Moscow State University MoscowRussia Lomonosov Moscow State University Moscow Russia Vinogradov institute of Geochemistry Irkutsk Russia institute of precambrian geology and geochronology ras Saint-PetersburgRussia Vernadsky institute of Geochemistry and Analytical Chemistry ras MoscowRussia

Zoned tourmaline （schorl-dravite） in the matrix of hydrothermal explosive breccia and ore veins in gold deposits, Chita region, Eastern Transbaikalia, Russia, are associated with Na- and K-rich porphyry-type subvolcanic intrusives. 61So values of tourmaline from three gold deposits （Darasun, Talatui, Teremkinskoye） are ＋8.3%, ＋7.6%, and --6.0% and calculated 6180 values of fluids respon- sible for the tourmalinization are ＋7.3%, ＋7.7%, and ＋4.2%, respectively. These data imply an igneous fluid source, except at the Teremkin deposit where mixing with meteoric water is indicated. Wide ranges of Fe3＋/Fetot and the presence of vacancies characterize the Darasun deposit tourmaline indicating wide ranges off（O2） and pH of mineralizing fluids. Initial stage tourmalines from the gold deposits of the Darasun ore district are dravite or high mg schorl. Second stage tourmaline is characterized by oscillatory zoning but with Fe generally increasing towards crystal rims indicating decreasing temperature. Third stage tourmaline formed unzoned crystals with XMg （mole fraction of Mg） close to that of the first stage tourmaline, due to a close association with pyrite and arsenopyrite. From Fe^3＋/Fetot values, chemical composition and crystallization temperatures, logf（O2） of mineralizing fluids ranged from ca. -25 to 20, much higher than for the gold-bearing beresite-listvenite association, indicating that tourmalinization was not related to gold mineralization.

关键词： Tourmaline composition Fluid inclusions Oxygen isotopes Gold deposits Transbaikalia Russia

Zircon Xenocrysts from the Shaka Ridge Record Ancient Continental Crust:New U-Pb Geochronological and Oxygen Isotopic Data

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Journal of Earth Science 2022年第1期33卷 5-16页

作者： Sergey G.Skublov Natalia A.Rumyantseva Qiuli Li Boris G.Vanshtein Dmitriy I.Rezvukhin Xianhua Li institute of precambrian geology and geochronology of Russian Academy of Sciences St.Petersburg 199034Russia Saint Petersburg Mining University St.Petersburg 199106Russia institute for geology and Mineral Resources of the World Ocean(VNIIOkeangeologia) St.Petersburg 190121Russia State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Sobolev institute of geology and Mineralogy Siberian Branch of the Russian Academy of SciencesNovosibirsk 630090Russia

Over the past two decades, a significant number of discoveries of ancient zircon xenocrysts in ocean-floor magmatic rocks have been reported. These findings provide compelling evidence for the presence of ancient continental crust within young oceanic lithosphere. Almost all finds of ancient zircon xenocrysts within oceanic crust are from the Mid-Atlantic Ridge. For other localities, however, similar data are very limited. This report presents the first age determinations(U-Pb, SHRIMPII) and isotope-geochemical data(oxygen, trace and rare earth elements) for zircon xenocrysts from gabbro-diorites of the Shaka Ridge, in the vicinity of the Shaka fracture zone, near the western end of the Southwest Indian Ridge. The work is based on a study of bottom rock material dredged during expeditionary research on the R/V"Akademik Fedorov"(Russia) in 2016. The U-Pb isotope system of the zircon xenocrysts recorded a crystallization age of ~2.8 Ga at an upper discordia intercept and an age of ~600 Ma interpreted as the timing of a superimposed thermal event at a lower discordia *** zircon xenocrysts show geochemical signatures of magmatic origin, i.e., fractionated REE distribution spectra with an increase in chondrite-normalized values from light to heavy REE, positive Ce anomalies and negative Eu anomalies, and high Th/U ratios(0.59-7.77). In discrimination diagrams based on a series of inter-element relationships, zircon compositions fall into the fields of zircons from rocks of continental crust, mostly granitoids. The Li content of the zircons is high(1.8 ppm-50 ppm),adding further evidence to their derivation from rocks of continental crust. During their residence within young oceanic crust, the zircon xenocrysts experienced alterations under the influence of submarine high-temperature hydrothermal fluids, which selectively affected the distribution of trace elements in the zircons and reduced the δ;O values to 1.75‰-3.15‰. The presence of obviously older zircons

关键词： zircon U-Pb geochronology oxygen isotopes trace elements rare earth elements Shaka Ridge South Atlantic Southwest Indian Ridge

Magmatic systems of large continental igneous provinces

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Geoscience Frontiers 2017年第4期8卷 621-640页

作者： E.Sharkov M.Bogina A.Chistyakov institute of geology of Ore Deposits PetrographyMineralogy and Geochemistry RAS

Large igneous provinces（LIPs） formed by mantle superplume events have irreversibly changed their composition in the geological evolution of the Earth from high-Mg melts（during Archean and early Paleoproterozoic） to Phanerozoic-type geochemically enriched Fe-Ti basalts and picrites at 2.3 *** propose that this upheaval could be related to the change in the source and nature of the mantle superplumes of different *** first generation plumes were derived from the depleted mantle,whereas the second generation（thermochemical） originated from the core-mantle boundary（CMB）.This study mainly focuses on the second（Phanerozoic） type of LIPs,as exemplified by the midPaleoproterozoic Jatulian-Ludicovian LIP in the Fennoscandian Shield,the Permian-Triassic Siberian LIP,and the late Cenozoic flood basalts of *** latter LIP contains mantle xenoliths represented by green and black *** xenoliths are fragments of cooled upper margins of the mantle plume heads,above zones of adiabatic melting,and provide information about composition of the plume material and processes in the plume *** on the previous studies on the composition of the mantle xenoliths in within-plate basalts around the world,it is inferred that the heads of the mantle（thermochemical） plumes are made up of moderately depleted spinel peridotites（mainly lherzolites）and geochemically-enriched intergranular fluid/***,it is presumed that the plume heads intrude the mafic lower crust and reach up to the bottom of the upper crust at depths-20 *** generation of two major types of mantle-derived magmas（alkali and tholeiitic basalts） was previously attributed to the processes related to different PT-parameters in the adiabatic melting zone whereas this study relates to the fluid regime in the plume *** is also suggested that a newly-formed melt can occur on different sides of a critical plane of silica undersaturation and can acquire either alkalic or tholeiitic composition de

关键词： Magmatic systems LIP Mantle plume Paleoproterozoic Mantle xenoliths Basalts

Rock-magnetic investigation of Siberia loess and its implication

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Chinese Science Bulletin 2000年第23期45卷 2192-2198页

作者： Kazansky Alexey Matasova Galina Zykina Valentina Petrovsky Eduard Jordanova Neli institute of geology UIGGM SD RASNovosibirskRussiaInstitute of GeologyUIGGM SD RASNovosibirskRussiaInstitute of GeologyUIGGM SD RASNovosibirskRussiaGeophysical InstitutePragueCzech RepublicGeophysical InstitutePragueCzech Republic

Multiple-rock magnetic investigations conducted on the loess-paleosol sequences at Kurtak in Southwestern Siberia reveal that the mass-normalized low-field magnetic susceptibility profiles reflect changes in lithology between relatively unweathered primary loess of glacial periods and the interglacial paleosols. Maxima in susceptibility values correspond with the least-weathered loess horizons, and minima with the humic horizons of soils. Frequency-dependent susceptibility of the loess-paleosol sequences at Kurtak is very low and practically uniform, indicating the dominance of non-SP ferrimagnetic minerals and negligible pedogenesis. The history of temperature-dependence of susceptibility (IDS) and stepwise acquisition of the isothermal remanent magnetization (SIRM) have confirmed that magnetite is predominant magnetic mineral, and only few maghemite and probably hematite are present within the studied section. Anisotropy of the magnetic susceptibility (AMS) can be used to monitor tilt and

关键词： Siberia loess rock-magnetism paleoclimate.

Tectonometamorphic Cycles in Different Geodynamic Conditions

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Journal of Earth Science 2000年第4期19卷 11-19页

作者： Miller Yu V Dufour MS institute of precambrian geology and geochronology Russian Academy of ScienceSt-Petersburg 199034Russia Geological Faculty St-Petersburg State University St-Petersburg 199034Russia

Formation and attenuation of crust thermal anomalies, accompanied by development of geological structures, are governed by special laws, together with metamorphism and other endogenic process, form tectonometamorphic cycle (TMC). Because of rock rheology under metamorphic conditions, the structures, concurring with metamorphism, reflect geodynamic conditions much more perfect than those of the structures of nonmetamorphosed rocks. For this reason, structural investigations open wide, sometimes unique, possibilities for geodynamic research into regional metamorphosed terrains. The TMC features under different geodynamic conditions are shown with examples of California (subduction), Himalaya and Junggar Alatau (collision), and Northwest environs of the White Sea (polycyclic development). The analysis of these units serves as basis of some general conclusions. TMC, the steady pattern of crust thermal anomalies manifestation, does not practically depend on peculiarities of metamorphism. At lower and middle crust levels, occur the high-temperature complete cycles that include following two stages. The first is represented by nappes and paragenes of parallel bedding flow, the second, by linear folds, domes and faults. At top levels of fold complexes display the low-temperature reduced cycles, expressed only by structures of the second stage. There are gradual transitions between the complete and reduced cycles. Thermal anomalies in the first stage of complete cycles devolop against the background of large horizontal displacements at contacts between interacting plates or are genetically connected with their gently sloping fault planes. Of all structural elements of the cycles, in compressional environments (nappes, linear folds, domes etc.), only the structures of the first stage of complete cycles can be considered as indications of plate tectonics. Presence of such structures at the most ancient supracrustal complexes point to existence of plate tectonics already at

关键词： complete and reduced tectonometamorphic cycles nappe parallel bedding flow schistosity linear fold dome.

Gold mineralisation and orogenic metamorphism in the Lena province of Siberia as assessed from Chertovo Koryto and Sukhoi Log deposits

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Geoscience Frontiers 2016年第3期7卷 453-481页

作者： Marina A.Yudovskaya Vadim V.Distler Vsevolod Yu.Prokofiev Nickolay N.Akinfiev institute of geology of Ore Deposits PetrographyMineralogy and Geochemistry RAS EGRI University of the Witwatersrand

The Chertovo Koryto gold deposit（80 t Au at 1.84 g/t） in the Lena world-class province,Siberia,is hosted in a metamorphosed sequence of the Paleoproterozoic Mikhailovsk Formation that comprises the oldest black shale strata of the Baikal-Patom *** mineralisation is confined to the thrust zone complicated with a conjugate anticline fold,zones of shearing and *** struaural position of the mineralisation is similar to that at the giant Sukhoi Log deposit in the neighbouring Mama-Bodaibo *** the latter,the isotope age data suggest that Khomolkho black shales,hosts to Sukhoi Log mineralisation,are of Ediacaran age and underwent prograde metamorphism during early *** geochemical composition of the terrigenous rocks that host Sukhoi Log,Chertovo Koryto,and a number of other deposits at the various stratigraphic levels throughout the Proterozoic sequence have much in *** do not show elevated metal contents above the common black shale abundances,except for Au and As,which is at variance with the accepted view on diagenetic enrichment of black shales in the Lena *** occurrence of sagenitic rutile in quartz and chlorite pseudomorphs after biotite and other petrographic observations provide evidence on a retrograde nature of the metamorphic mineral assemblages in the Mikhailovsk *** sulphides are pyrrhotite and arsenopyrite with very minor pyrite at Chertovo Koryto,whereas pyrite is the predominant sulphide in the Sukhoi Log *** inclusion data on both deposits emphasise a high-temperature nature of the mineralisation albeit revealing great contrast in the fluid *** Log mineralisation was formed at mixing between low-salinity aqueous solutions and dense gaseous carbonic fluids,which facilitated effective gold scavenging and precipitation,as demonstrated by thermodynamic *** precursory devolatilisation of the Mikhailovsk sediments at the prograde stage results in the paucity of gaseous carbon

关键词： Gold Black shales Orogenic metamorphism Orogenic fluid Sukhoi Log Chertovo Koryto