The paper presents a modern metallogenic overview of Rudny Altai and the results of the study of the volcanic rocks associated with contrasting basalt-rhyolite formation, manifested as a consequence of riftogenic processes. There are two linear metallogenic subzones within the Rudny Altai Polymetallic Belt that extend in a northwesterly direction. The Zmeinogorsko-Zyryanovskaya subzone is the main one: it contains two-thirds of the belt’s deposits, three-quaters of Zn, Pb, Cu reserves, and four-fifths of Au and Ag, which are associated with Emsian-Givetian basalt-rhyolite formation. The Irtysh metallogenic subzons extends along the Irtysh Shear Zone, and is mainly composed of the Eifelian—Early Famennian basalt-rhyolite formation. Devonian bimodal volcanism occurred against a background of extension deformation with the formation of pull-apart basins. Taking into account the structure-kinematic characteristics of faults, the Devonian architecture of the Rudny Altai Block can be considered as a ‘negative flower’ (tulip) structures. Based on the trace element characteristics of initial basic rocks, the original magmas were the product of partial melting of metasomatised lithospheric mantle. This is confirmed by Pb-Pb studies of galena monofractions from the Rudny-Altai volcanogenic massive sulfide (VMS-type) deposites. The magma source of the subsequent major phases probably corresponded to the asthenosphere, which may have risen to the depth of the preceding melting region. The generation of significant volumes of felsic magmas, to which the main VMS-type deposits are genetically related, was most likely associated with large-scale melting of terrigenous strata of the pre-Devonian palaeoshelf under the influence of mantle magmas. The sequence of Devonian mineralisation types is considered to be a consequence of the change in the type of volcanism initiated by transtension tectonics. This is consistent with the concept that the formation of ore-forming systems VMS type is associated with periods of hydrothermal activity during the mantle upwelling under extensive tectonic settings.The antidromic nature of magmatism development resulted in a specific metallogeny of the region, expressed in the change of barite-polymetallic and polymetallic deposits of the Emsian-Eifelian stage (Zyryanovskoe, Tishinskoe, Ridder-Sokolnoe), pyrite-polymetallic at the Givetian stage (Belousovskoe, Talovskoe) and then copper-pyritic at the Frasnian-Early Famennian stage (Kamyshinskoe, Nikolaevskoe). The results obtained are consistent with the model of evolution of the marginal arc—back arc system, in which mantle uplift is associated with basin extension and plate rollback.

The paper presents new original data on the Devonian rift-related volcanism from the Rudny Altai, a marginal terrane of the Siberian continent (Altai-Sayan Fold Belt, western Central Asian Orogenic Belt). The extensional regime in relation to tectono-magmatic reactivation of the continental margin was accompanied by an intense flare up of bimodal-type shallow-marine volcanism and injection of subvolcanic intrusions. On the first stage basic magmatism evolved from (i) injection of "More LREE- and HFSE-enriched" dolerite (epsilon(Nd)(t) = +5.1) to (ii) eruption of their effusive analogues (epsilon(Nd)(t) = +1.4), and following "Less LREE- and HFSE-enriched" basalt (epsilon(Nd)(t) = +6.1). This stage reflects initial opening of the rift. On the second stage, volcanism evolved from (iii) "LREE- and HFSE-depleted" (epsilon(Nd)(t) = +5.4) to (iv) "LREE-enriched and HFSE-depleted" (epsilon(Nd)(t) = +4.1 to +4.7) types. This stage correspond to the prolonged opening of the pull-apart basin, as there is no geological evidence for island-arc uplift during this period. Variations in indicator HFSE ratios (Th/Yb, Nb/Yb and Zr/Y), enrichment of Nb relative to La and Th in combination with moderate Nd isotopic values resemble those for basalts from the behind-arc region with close spatial-temporal relation to rifting. The trace element variation indicates a change in the partial melting degree of the mantle source, from lower to higher, consistent with progressive rifting. The petrogenesis of magmas has been interpreted as shallow melting of a lithospheric mantle, metosomatised by a previous subduction event, and inherited geochemical signatures of relict mantle. The voluminous felsic magmatism was formed by crustal melting during lithospheric extension when basic magmas reached high crustal levels. The dacites yield zircon U-Pb ages of ca. 375 Ma, reflecting the peak of volcanic activity. The tectonic record bear evidence of strike-slip deformation, which could been induced by translation of arc and back-arc lithospheric plates. Summary: The Devonian evolution of the Altai Convergent Margin (NW Rudny Altai) of the Siberian continent was accompanied by the generation of basalt-dacite volcanism (similar to 380-375 Ma). Based on the sequence of volcanic phases and their geochemical variations in the time range, two stages corresponding to the initial and longterm opening of the pull-apart basin are distinguished. The petrogenesis of the magmas is interpreted as shallow melting of lithospheric mantle metasomatised by a previous subduction event and inheriting geochemical signatures of the relict mantle. The initial and subsequent magmatic phases can be reproduced by varying the degree of partial melting of the magma source from lower to higher, consistent with the evolution of the pullapart basin. Rift-related magmatism is caused by arc and back-arc plate translation, with a minor role for subduction factor.

The results of geological, geochemical, and isotopic–geochronological studies of Late Devonian granitoids of Rudny Altai, which formed at the Hercynian stage of tectonogenesis of the Altai–Sayan sector of the Central Asian Fold Belt, are presented. The isotopic U–Pb age of zircons ranges from 367 to 363 Ma. The geochemical characteristics indicate that leucogranites belong to high-K calc-alkaline series (SiO2 > 73 wt

The results of prior studies are generalized and the author’s data on the geology, geochemistry, and isotope geochronology of the Early–Middle Devonian volcanic series of Western Gorny Altai and Rudny Altai that are related to two large volcanic systems, the Altai–Minusinsk and Altai–Salair, respectively, are presented. The studied basalts have convergent geochemical characteristics between the rocks in back-arc basins and island arcs or their rear extension zones. It is considered that the back-arc-basin–island-arc system was developed in the Early–Middle Devonian on the Altai margin of the Siberian continent.

Представлены результаты геологических, геохимических и изотопно-геохронологических исследований субвулканических риолитов Западного Горного Алтая и Рудного Алтая, принадлежащих двум крупным герцинским вулканическим системам, Алтае-Минусинской и Алтае-Салаирской. Результаты изотопного U-Pb-датирования цирконов показали две группы возрастов: ~410-405 и 390-381 млн лет. Изотопно-геохимические характеристики риолитов демонстрируют высокие значения e Nd ( Т ) = +2,7…6,0 с относительно молодыми значениями модельных возрастов T (DM) = 851-966 млн лет в Рудном Алтае и более древними - до 1266 млн лет в Горном Алтае. Петрогеохимические характеристики указывают на принадлежность составов риолитов к пограничной области между внутриплитными и островодужными кислыми магмами. Полученные результаты соответствуют двухстадийной эволюции вулканизма и его миграции от континента к океану.

The paper presents new original data on the Devonian felsic volcanism of the NW Rudny Altai (Russia) in the west of Central Asian Orogenic Belt (CAOB) – the front part of the Altai convergent margin of the Siberian continent. Two geochemical types of subvolcanic rhyolites were emplaced synchronously with the bimodal rhyolite-basalt association, which began to form in the end-Emsian, and clearly manifested on the border of the Givetian and the Frasnian. The rhyolites yield zircon U-Pb ages of ca. 390 Ma (R1-type) and 380 Ma (R2- and R3-types), reflecting two peaks of the volcanic activity. Most of these rocks have extreme petrochemical characteristics of high SiO2 contents and have contrast Na/K ratios. Their compositions are transition between calc-alkaline and tholeiite series: (La/Yb)n ~ 2–7, Zr/Y ~ 4 (Zr < 350 ppm) and La/Sm ~ 0.55–1. Rhyolites bear the distinctive geochemical signature of A-type felsic magma, such as enrichments in Zr, Nb, Y and Ce (>350 ppm), Zr (>250 ppm), and high Ga/Al (>2.6) values. The island-arc-like R1-rhyolite formed immediately after the beginning of rifting due to widespread crustal melting under reduced conditions. The generation of rift-like R2- and R3-rhyolites took place under non-equilibrium conditions, synchronously with the rise in the upper crust of Givetian-Frasnian basic magmas, as a result of the active lithospheric extension and high thermal input from the underlying hot mantle. We propose an extension regime in the transition area between the island-arc and back-arc basin for the origin of rhyolites. The study of the Devonian volcanism of the Rudny Altai gives important information about the processes that occurred at the initial stage of the formation of the Altai convergent margin.

The paper presents the results of geological, geochemical and isotope-geochronological studies of subvolcanic rhyolites of the Western Gorny Altai and Rudny Altai which have related to two large volcanic systems, the Altai-Minusinsk and Altai-Salair, respectively. The results of U-Pb isotopic dating of zircons revealed two groups of ages ~410-405 and 390-381 million years. Isotope-geochemical characteristics of rhyolites show relatively high values of εNd(T) = +2,7...6,0 with relatively young values of model ages T(DM) = 851-966 Ma in the Rudny Altai and more ancient - up to 1266 Ma in the West Gorny Altai. Geochemical characteristics indicate that its composition is consistent with transitional field between within-plate and island-arc felsic magmas. The results obtained correspond to the two-stage evolution of volcanism and its migration from the continent to the ocean.

The paper presents new original data and a review of previous studies on the Late Carboniferous - Early Permian granitoids of the Kunush and Kalguty intrusive complexes from the Kalba fold belt (East Kazakhstan). These rocks formed at the initial post-collisional stage of the Irtish-Zaisan orogen in the western Central Asian Orogenic Belt (CAOB). The granitoids form isometric or NW linear intrusions inside the Late Devonian - Early Carboniferous metasediments which overlap the accretionary lithology of the Kalba fold belt in front of the Altai active margin of the Siberian continent. These granitoids contain zircon grains with U-Pb ages of ca.308-291 Ma, synchronous with the peak post-orogenic magmatic event at similar to 300 Ma in the CAOB. The Kunush high-Na granitoids, with high SiO2 (67-72%) and Al2O3 (15-18%) contents and the Na2O/K2O ratio (1.94-6.43), and low HREEs (Yb = 0.22-0.93 ppm) but moderate Sr/Y ratios (47-179), Mg# (35-55) and Ni, Cr, are generally common to high-Al TTG-series with non-subduction geochemical signatures. The Kalguty granitoids mostly belong to calc-alkalic to subalkalic high-K series, have non-corundum CIPW-norm compositions and mainly weakly peraluminous (ASI = 0.97-1.09) characteristics. Their Fe* = 0.7-1 at 62-74 wt.% SiO2 and relatively high Y/Nb (2-4) and Rb/Nb (9-18) ratios are similar to transitional compositions reported for fractionated I- and A(z)-type post-orogenic granites worldwide. The Kunush high-Na and Kalguty high-K granitoids formed at different depths in the crust and the parent melts were derived from metabasaltic (MORB; P = 10-15 kbar) and metagranitic (TTG-like; P < 10 kbar) protoliths, respectively. We propose that relaxation of tangential compression after oblique collision and the following thermal impact of mafic magma that acted simultaneously at different crustal depths, along with decompressional partial melting, may be a basic petrological scenario for synchronous formation of geochemically different granitoids.

Pacific-type orogens (fold belts) hosting accretionary complexes are places keeping records of the evolution of paleo-oceans, and formation and transformation of continental crust at their active convergent margins. Pacific-type orogeny induces destruction of crustal materials, their subduction to the deep mantle, generation of hydrous-carbonated plumes in the mantle transition zone (MTZ) and its related intra-plate magmatism. We propose a new approach for linking paleo-oceans, active margins and intra-plate magmatism in central and eastern Asia. The approach "stands" on three "whales": the model of Ocean Plate Stratigraphy (OPS), the parameters of Pacific-type convergent margins and a model of hydrous-carbonated plumes. The OPS model evolved from extensive studies of accretionary complexes in the western Pacific, in particular in Japan; it allows differentiating oceanic plates of one paleo-ocean and evaluating their sizes and ages. An important issue for reconstructing the history of paleo-oceans is to estimate major parameters of the Pacific-type convergent margins: accreting vs. eroding, geometrical length, and life time. For the eroding margins we must define major periods of tectonic erosion and transportation of oceanic and continental materials to the deep mantle and evaluate a possibility of their accumulation in the MTZ. All this would allow us to develop a holistic model linking the evolution of paleooceans, the accretion and erosion of oceanic and continental crust materials at Pacific-type convergent margins, mantle metasomatism and intra-plate magmatism.

We studied the geologic position, mineralogy, petrography, chemical composition, and age of granitoids of the Gamov batholith located in the Heilongjiang-Grodekovo terrane, southern Primorye (Russia). The studies have revealed four intrusive rock phases, from gabbro to leucogranites, in the massif. U-Pb zircon dating of tonalites of phase II and leucogranites of phase IV (254 +/- 4 and 259 +/- 2 Ma, respectively) shows that the intrusion of granitoids took place in the Late Permian without a significant gap in time. Structural investigations gave evidence for the intrusion in the E-W compression setting. Geochemical studies have revealed granitoids of strongly different compositional types in the intrusive massif: gabbroids, quartz diorites and tonalites with characteristics of low-alumina TTG, calc-alkalic granodiorites and I-type granites, and moderately alkaline leucogranites. The obtained data, together with the results of previous research into the Permo-Triassic granitoids of southern Primorye, reject their formation as a result of the evolution of the Solonker oceanic structures and suggest a more intricate tectonic scenario, which calls for additional study. (C) 2015, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

The paper presents first U–Pb zircon ages and geochemical data from Carboniferous granitoids (tonalites and plagiogranites) of the Char suture–shear zone in East Kazakhstan, which is located in the north-western Central Asian Orogenic Belt (CAOB). The study included analysis of geological setting, major and trace elements, and rock petrogenesis. The Char tonalites and plagiogranites occur as NW-striking linear chains inside Visean serpentinite mélange. Petrographycally, the tonalites show signs of syntectonic deformation, and the plagiogranites are less deformed suggesting their later intrusion. The tonalites yielded a LA-ICP-MS zircon age of ca. 323 Ma, i.e. exactly at the boundary between the early and late Carboniferous. Compositionally, the tonalites and plagiogranites are characterized, respectively, by high SiO2 (67–70 and 73–74 wt.%) and Al2O3 (17–19 and 14–15 wt.%), Sr/Y > 40 and low Yb = 0.2–0.5 ppm. Their multi-element patterns show clear Nb-Ta negative anomalies. The low Nb/Ta ratios (7–15) and Zr (114–191 ppm) suggest a MORB-type protolith (amphibolite) with subchondritic Nb/Ta (8–17) and low Zr (1–72 ppm). The low contents of K and Rb suggest weak assimilation of the melts by island arc felsic crust. The subchondritic Nb/Ta ratios exclude their derivation by the melting of subducted/dehydrated MORB. We argue that the Char high-Al tonalites and plagiogranites formed by the melting of hydrated MORB at the base of the mafic lower crust at pressures of 10–15 kbar. The occurrences of the Char tonalites and plagiogranites inside the Visean serpentinite mélange overlapped by Serpukhovian conglomerates, their alignment parallel to deformation zones, and their geochemical features suggest their origin by the melting of mafic lower crust in relation to the collision of the Siberian and Kazakhstan continents.

We present new data on the geologic position, composition, and isotope characteristics of the Early Cretaceous granitoids of the Samarka terrane, Sikhote-Alin’, formed on a transform continental margin. Geological and geochronological data show that these granitoids were generated at two stages of magmatism: in the first half (Hauterivian–Barremian, 130–123 Ma) and second half (Albian–Cenomanian, 110–98 Ma) of the Early Cretaceous. Granitoids of the first stage form an autonomous (free of basic precursors) unimodal melanogranite–granite association and are characterized by normal alkalinity with domination of K over Na, low contents of Ca, and elevated contents of Al2O3. By composition, these are S-granites with a model Nd age of ∼1.3 Ga. Granitoids of the second stage are of more diverse petrogeochemical types. They show wider variations in K/Na and A/CNK, are richer in Ca and, sometimes, Sr, and are poorer in P than the granitoids of the first stage. Their compositions form a continuous trend from S- to I-granites, and their model Nd age is ≤1.2 Ga. Comparison of the petrochemical, trace-element, and isotope characteristics of the Early Cretaceous granitoids and upper-crustal rocks (sandstones and siltstones of the turbidite matrix of a Jurassic accretionary prism and basalts from the inclusions in it) of the Samarka terrane and the coeval garrboids has shown that the potassic S-granitoids formed at the early (Hauterivian–Barremian) stage of magmatism as a result of the anatexis of upper-crustal sedimentary rocks. At the late (Albian–Early Cenomanian) stage, the intrusion of mantle magmas led to a temperature increase in the lower crust, which favored more active anatexis, involvement of high-melting substrates (oceanic basalts) in the granite formation, and interaction of mantle and crustal magmas. This resulted in a great diversity of granitoids (from S- to I-type).

The geologic position, age, petrologic composition, and petrogenesis of mesoabyssal plagiogranites in northern Rudny Altai, dated earlier at the Early–Middle Devonian, are considered. The Middle Carboniferous (322–318 Ma) age of granitoids has been substantiated by isotope-geochronological data (U–Pb zircon dating and Ar–Ar amphibole and biotite dating). Geologic-structural studies showed that the intrusion of granitoids took place at the time when compression was changed by sinistral faulting. This led to the conclusion that the granitoids formed at the peak of the collision between the Siberian and the Kazakhstan paleocontinents. Geochemical and isotope studies showed that most of the analyzed plagiogranites belong to high-alumina (continental) type and resulted from the deep melting (~ 15 kbar) of metabasic substrates compositionally similar to N-MORB (judging from results of geochemical modeling and the Nd isotope composition). The presence of plagiogranites of low-alumina (oceanic) type in the postgranite dike series testifies to the melting of the Rudny Altai heterogeneous crust at different depths during its collisional thickening.

Оловоносные гранит-лейкограниты Пиа Оак, расположенные в провинции Као Банг Северного Вьетнама, слагают штокообразное интрузивное тело гипабиссальной фации глубинности. Вмещающие породы представлены карбонатными толщами раннедевонского и “черными” сланцами раннетриасового возраста. Геохронологический возраст гранит-лейкогранитов Пиа Оак отвечает позднему мелу: Т = 83.5 ± 6.2 млн. лет, 87Rb/86Sr метод; Т = 89.7 ± 1.0 млн. лет, 39Ar/40Ar метод. Массив имеет простое гомодромное строение: двуслюдяные и мусковитовые гранит-лейкограниты редкометалльные аплиты, пегматиты оловоносные грейзены и гидротермальные жилы. Петрографические и микроструктурные исследования показывают, что на позднемагматической стадии произошло резкое изменение условий кристаллизации гранит-лейкогранитной магмы, вызвавшее инконгруэнтное замещение протолитионита мусковитом. По данным изучения расплавных и сосуществующих флюидных включений солидусная кристаллизация проходила во флюидонасыщенных условиях при 635–600°С. По вещественному составу гранит-лейкограниты массива Пиа Оак отвечают редкометалльно-плюмазитовому геохимическому типу (по Л.В. Таусону), а по содержаниям редких элементов достигают уровня литий-фтористой фации. Состав аплитов и пегматитов показывает, что дифференциация не сопровождалась существенным накоплением литофильных и летучих компонентов в остаточном расплаве, а высокая редкометалльность была присуща гранит-лейкогранитной магме изначально. Наиболее вероятным источником расплава являлись структурно-вещественные комплексы протерозойского возраста и перекрывающие их “черные” сланцы нижнего триаса.

Intrusions of the Irtysh Complex are spatially restricted to the regional Irtysh Shear Zone (ISZ) and are hosted in blocks of high-grade metamorphic rocks (Kurchum, Predgornenskii, Sogra, and others) in the greenschist matrix of the ISZ. The massifs consist of contrasting rock series from gabbro to plagiogranite and granite at strongly subordinate amounts of diorite and the practical absence of rocks of intermediate composition (tonalite and granodiorite). The complex was produced in the Early Carboniferous, simultaneously with the onset of the origin of the ISZ itself. The granitoids composing the complex affiliate with diverse petrochemical series (from subaluminous plagiogranite of the andesite series to granite of the calc-alkaline series) and contain similar REE and HFSE concentrations [total REE = 103–163 ppm (La/Yb) n = 3.59–5.44, Zr (200–273 ppm), Nb (7.6–10.6 ppm), Hf (6.1–7.6 ppm), and Ta (0.68–1.19 ppm)] but are different in concentrations in LILE [Rb (3–9 and 121–221 ppm), Sr (213–375 and 77–148 ppm), and Ba (67–140 and 240–369 ppm)] and isotopic composition of Nd (ɛNd(T) from +5.3 in the plagiogranite to −1.2 in the granite) and O (δ18O from +9.4 in the plagiogranite to +14.5 in the granite). Data on the geochemistry and isotopic composition of metamorphic rocks of the Kurchum block and numerical geochemical simulations indicate that the granitoids were generated via the melting of a heterogeneous crustal source, which consisted of upper crustal metapelites and metabasites of the oceanic basement of the blocks of high-grade metamorphic rocks. The differences in the chemical and isotopic compositions of the granitoids were predetermined by the mixing of variable proportions of granitoid magmas derived from metapelite and metabasite sources.

The Piaoak tin-bearing granite-leucogranites located in the Caobang Province of Northern Vietnam compose a stock-like hypabyssal body. Host rocks are represented by Early Devonian carbonate sequences and Early Triassic “black” shales. The geochronological age of the Piaoak granite-leucogranites corresponds to the Late Cretaceous: T = 83.5 ± 6.2 Ma, 87 Rb/ 86 Sr method; T = 89.7 ± 1.0 Ma, 39 Ar/ 40 Ar method. The massif has a simple basic to acid order: two-mica and muscovite granite-leucogranite → raremetal aplites, pegmatites → tin-bearing greisens and hydrothermal veins. The petrographic and microstructural studies revealed a sharp change in crystallization conditions of the granite-leucogranite magma at the late magmatic stage and formation of muscovite via incongruent melting of protolithionite. The study of melt and coexisting fluid inclusions showed that solidus crystallization occurred under fluid-saturated conditions at 635–600°C. In composition, the granite-leucogranites of the Piaoak Massif correspond to the raremetal-plumasite geochemical type (according to L.V. Tauson), and reach Li-F facies in terms of their rare-element composition. The composition of aplites and pegmatites demonstrates that granite-leucogranite magma did not accumulate lithophile and volatile components in the residual melt during differentiation, but was initially enriched in rare-metals. It is most probable that the melt was generated from Proterozoic lithotectonic complexes and overlaying Lower Triassic “black” shales.

We consider the geologic occurrence and PT-conditions of the generation and crystallization of siliceous melts that formed volcanic structures within the Altai collisional system of Hercynides. The data on the geologic occurrence, internal structure, and petrogeochemical age of rocks are presented, as well as results of the thermobarogeochemical studies of inclusions in minerals. The performed investigations showed the presence of siliceous dacitic melts in the studied volcanic structures. These melts were generated in the lower crust (~10 kbar, 1000–1200 ºC) as a result of the partial melting of crustal substrates under the influence of high-temperature mantle melts.

Stanniferrous granite-leucogranite massifs in Vietnam to which the bedrock and placer commercial deposits of cassiterite are associated (Timtuc etc.) are of late Cretaceous age (∼85 Ma by Rb-Sr and Ar-Ar isotope dating). These massifs are presented by stocks and fracture intrusions (to 100 km 2 in area) of simple homodromic structure: biotite granites ⇒ two-mica and muscovite leucogranites ⇒ topaz-containing aplites ⇒ rare-metal pegmatites.