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(a) Shaded relief image (illuminated from the NW), representing the digital elevation model of the NW Rudny Altai, illustrating the location of the two Devonian volcanic belts formed along the NW direction of deformation in the boards of the Alei basement rhomboidal-shaped structure. (b) The principal tectonic scheme of the Rudny Altai, illustrating the division on structure-formation units. (c) Detailed three-dimensional topographic mapping scheme on panel a, illustrating the position Alei structure and Shipunikha rift in structure of NW Rudny Altai. The vertical scale is increased five times.
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... Rudny Altai tectonic block is located on the territory of Russia, Kazakhstan and Chinese Altai, and extends in the North-Western direction for N500 km with a width of about 100 km, in the strip between the North-Eastern regional faults (NEF) and Irtysh Shear Zone (ISZ); Fig. 2a. On the basis of tectonic and volcanic zoning (Kulkov, 1980), its territory is subdivided into five zones: (i) Aley in Russia; (ii-iv) Sinukha-Holzun, Nizhnebukhtarma and Yuzhnoaltai in Eastern Kazakhstan ( Bespaev et al., 1997;Scherba et al., 1998); and (v) Ashele in Xinjiang of China (e.g. Wan et al., 2010;Wu et al., 2015;Yang et ...
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... et al., 1994;Bespaev et al., 1997;Saraev et al., 2012). NW Rudny Altai is represented by the so-called Alei block -the outcrop of the Caledonian deformed basement, with a total size of 200 × 50-60 km. In Early Devonian the Alei Block was subsided and formed a rhomboidal-shaped structure, like pull-apart basin, now looks like half-graben (Fig. 2a). This structure is bounded by the general systems of north-western and sub-latitude faults. The first of them correspond to the ISZ and the NEF zone formed at the stage of formation of the Altai convergent margin, since they control the emplacement of two volcanic belts (Fig. 2c). According to geological mapping at a scale of 1:200,000 ...
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... structure, like pull-apart basin, now looks like half-graben (Fig. 2a). This structure is bounded by the general systems of north-western and sub-latitude faults. The first of them correspond to the ISZ and the NEF zone formed at the stage of formation of the Altai convergent margin, since they control the emplacement of two volcanic belts (Fig. 2c). According to geological mapping at a scale of 1:200,000 (Murzin et al., 2001), these volcanic belts in the sides of the Alei structure were formed synchronously; although it has not yet been determined whether the compositions of volcanic rocks from these belts are identical. The formation of feathering sub-latitudinal faults ...
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... rhyolites. The first stage total rock thickness is ~400 m. The second pronounced stage or so-called "Givetian -Frasnian rhyolite-basalt flash" corresponded to the clear mode of extension, and the formation of the so-called Shipunikha rift-like structure in the rear part of the NW Rudny Altai, accompanied by fractured effusions of basalts (Fig. 2a). This stage includes three volcanic rhythms, generally called the third, fourth and fifth. Accordingly, the third rhythm covers the period of formation of the varied stratified strata, consisting of lava, lava-breccia, tuffs and felsic ignimbrites composition (Fig. 3). The fourth rhythm is reflected by the eruptions of basalt flows ...
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... MS-rhyolites were collected mainly from the NE volcanic belt (Fig. 2) including several volcanic centers located in a chain on a direction NW-SE: Voronezh, Karaulny, Butochny and Sadovushka ( Fig. 4a-h). Butochny and Sadovushka were originally parts of a single volcanic center, but now they are separated by the local pull-apart structure inside the Sipunikha rift (Fig. 2). The volcanic center Kryuchki, ...
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... collected mainly from the NE volcanic belt (Fig. 2) including several volcanic centers located in a chain on a direction NW-SE: Voronezh, Karaulny, Butochny and Sadovushka ( Fig. 4a-h). Butochny and Sadovushka were originally parts of a single volcanic center, but now they are separated by the local pull-apart structure inside the Sipunikha rift (Fig. 2). The volcanic center Kryuchki, the only exposure of MS-rhyolite in the SW volcanic belt, was also collected for this study (Fig. 2). Subvolcanic intrusions occur as stock-, sill-and dike-like bodies localized inside the Late Emsian -Early Givetian stratified volcanogenic-sedimentary deposits of the first stage (Fig. 3). A large number ...
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... Karaulny, Butochny and Sadovushka ( Fig. 4a-h). Butochny and Sadovushka were originally parts of a single volcanic center, but now they are separated by the local pull-apart structure inside the Sipunikha rift (Fig. 2). The volcanic center Kryuchki, the only exposure of MS-rhyolite in the SW volcanic belt, was also collected for this study (Fig. 2). Subvolcanic intrusions occur as stock-, sill-and dike-like bodies localized inside the Late Emsian -Early Givetian stratified volcanogenic-sedimentary deposits of the first stage (Fig. 3). A large number of rhyolites have experienced significant brittle deformations, and are quite often subject to secondary alterations, including ...
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... separated in one batch with the zircons from R2-rhyolite, we assume that clogging of this sample could occur. If we calculate the total weighted average age obtained for all zircon grains from this sample, it yields a value of ~384 Ma, which contradicts the stratigraphic data, since at this point there was a volcanic pause in the NW Rudny Altai (Fig. 3; Murzin et al., 2001). On the other hand, the Phase 1 1 1 1 1 1 2 2 2 3 3 3 3 № ms-1/2 ms-1/3 ms-12 ms-14/1 ms-14/2 ms-14/3 ms-13/1 ms-30/2 ms-16 ms-17 ms-19 ms-22 ms-32 Sr 33 36 35 129 158 112 41 96 50 79 144 69 obtained variations of 206 Pb/ 238 U isotopic ages are still within the accuracy of the LA-ICP-MS method used. Zircon grains of sample №MS-8 ...
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... relationships between Nb, Y, Zr and Ce, and ratios of Ga/Al (1.26-3.52), and Zn (9-187 ppm) concentrations, show that the R1-rhyolite has continuous transitional characteristics between the OGT (unfractionated M-, I-and S-granite) and A-type felsic rocks ( Fig. 12a- f; Whalen et al., 1987). In contrast, the R2-and R3-rhyolites are marked only in the OGT-field, since the total Nb, Y, Zr and Ce (119-242 ppm), and Ga/Al (0.51-1.39) values; and Zn (52-171 ppm) contents are relatively low. In the Nb vs. Y and Rb vs. Y + Nb tectonic discrimination diagrams ( Pearce et al., 1984), all of the rhyolites are ...
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... marked only in the OGT-field, since the total Nb, Y, Zr and Ce (119-242 ppm), and Ga/Al (0.51-1.39) values; and Zn (52-171 ppm) contents are relatively low. In the Nb vs. Y and Rb vs. Y + Nb tectonic discrimination diagrams ( Pearce et al., 1984), all of the rhyolites are transition between volcanic-arc (I-type) and within-plate (A-type) fields ( Fig. 12g-h; Whalen et al., 1987). Although the variations in Rb are coherent with K 2 O, we neglected it in this case because the reason for that the rhyolites compositions plot on the border between the fields of normal arcrelated and within-plate felsic magmas is due to Y + Nb (32-92 ppm) and Ta + Nb (7-15 ppm) abundances. All rhyolites possess ...
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... K 2 O, we neglected it in this case because the reason for that the rhyolites compositions plot on the border between the fields of normal arcrelated and within-plate felsic magmas is due to Y + Nb (32-92 ppm) and Ta + Nb (7-15 ppm) abundances. All rhyolites possess low Rb (b200 ppm) contents, which is incompatible with a syn-collision setting (Fig. 12h). Consequently, some of the R1-rhyolite bear the distinctive geochemical signature of A-type felsic magmas, such as: (i) total enrichment in Zr, Nb, Y and Ce (N350 ppm), Zr (N250 ppm), and high Ga/Al values (N2.6; Whalen et al., 1987). In general, if we consider all MSrhyolites, they have transitional geochemical characteristics that ...
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... characteristics that resemble those of felsic rocks of the subduction-related extension geodynamic settings. However, this magmatism was unlikely to be associated with the rebound of the oceanic plate following slab break-off and extensional detachment of subduction orogen, like the Cordillera of North America (Whalen and Hildebrand, 2019); Fig. ...
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... the geochemical characteristics of MS rhyolites, their initial geochemical type is still difficult to identify. As suggested to us Prof. Bruno Scaillet "All the types discussed here are metaluminous". (i) Obviously, the parental magmas of the MSrhyolites were hardly peralkaline in nature, as was observed from their Zr/Ti and Nb/Y ratios (Fig. 10а and Fig. 12j). (ii) It is also unlikely that these magmas were peraluminous type, because they have Atype evolutionary trend (Fig. 12f), and are clearly different from highly fractionated S-and I-type granites, that would increase their Ga/Al ratios при crystal differentiation ( Wu et al., 2017). (iii) As discussed below, the R2-and R3-rhyolites ...
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... to us Prof. Bruno Scaillet "All the types discussed here are metaluminous". (i) Obviously, the parental magmas of the MSrhyolites were hardly peralkaline in nature, as was observed from their Zr/Ti and Nb/Y ratios (Fig. 10а and Fig. 12j). (ii) It is also unlikely that these magmas were peraluminous type, because they have Atype evolutionary trend (Fig. 12f), and are clearly different from highly fractionated S-and I-type granites, that would increase their Ga/Al ratios при crystal differentiation ( Wu et al., 2017). (iii) As discussed below, the R2-and R3-rhyolites are somewhat resemble high-silica residual and non-equilibrium melts associated with A-type magmas ( Barboni and Bussy, ...
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... 12f), and are clearly different from highly fractionated S-and I-type granites, that would increase their Ga/Al ratios при crystal differentiation ( Wu et al., 2017). (iii) As discussed below, the R2-and R3-rhyolites are somewhat resemble high-silica residual and non-equilibrium melts associated with A-type magmas ( Barboni and Bussy, 2013); Fig. 12f. In general, this indicates that the parental magmas of the MS-rhyolites should have been ...
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... show even greater geochemical affinity to the extensional rhyolites of the bimodal association of the Coastal Range in the Central Chile, related to Late Triassic intra-continental rifting in the Pacific Gondvana margin ( Fig. 13b; Morata et al., 2000). There is also a geochemical similarity to some of the bimodal-type rhyolites of Taupo Volcanic Zone, New Zealand (Deering et al., 2011), although the latter are mostly characterized by more depleted concentrations of MREEs and HREEs (Fig. 13b). As for the R2-and R3-rhyolites, it have the so-called seagull-like form of REE-patterns, which, in the simplifying assumptions, resemble those of some fractionated granites (FG) and A 2 -type granites attributed to post-orogenic extension tectonic setting ( Chappell and White, 1992;King et al., 1997;Chappell, 1999). ...
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... and A 2 -type granites attributed to post-orogenic extension tectonic setting ( Chappell and White, 1992;King et al., 1997;Chappell, 1999). However, all of the MS-rhyolites are clearly distinguished from post-orogenic granites, by a general depletion in REEs, lower HFSEs (e.g. Nb ~ 7-13 ppm; Th ~ 5-10 ppm) contents, and less pronounced Eu anomaly (Fig. 12c, d), for example, if we compare them with A 2 -granite from Southern Altai Range, China (Shen et al., 2011). By the same geochemical characteristics, they differ from bimodal-type rhyolites associated with initial rifting, as in Miocen ridge-subduction-related California-type environments (Johnson and O'Neil, 1984;Cole and Basu, 1992). ...
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... Rudny Altai tectonic block is located on the territory of Russia, Kazakhstan and Chinese Altai, and extends in the North-Western direction for N500 km with a width of about 100 km, in the strip between the North-Eastern regional faults (NEF) and Irtysh Shear Zone (ISZ); Fig. 2a. On the basis of tectonic and volcanic zoning (Kulkov, 1980), its territory is subdivided into five zones: (i) Aley in Russia; (ii-iv) Sinukha-Holzun, Nizhnebukhtarma and Yuzhnoaltai in Eastern Kazakhstan ( Bespaev et al., 1997;Scherba et al., 1998); and (v) Ashele in Xinjiang of China (e.g. Wan et al., 2010;Wu et al., 2015;Yang et ...
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... et al., 1994;Bespaev et al., 1997;Saraev et al., 2012). NW Rudny Altai is represented by the so-called Alei block -the outcrop of the Caledonian deformed basement, with a total size of 200 × 50-60 km. In Early Devonian the Alei Block was subsided and formed a rhomboidal-shaped structure, like pull-apart basin, now looks like half-graben (Fig. 2a). This structure is bounded by the general systems of north-western and sub-latitude faults. The first of them correspond to the ISZ and the NEF zone formed at the stage of formation of the Altai convergent margin, since they control the emplacement of two volcanic belts (Fig. 2c). According to geological mapping at a scale of 1:200,000 ...
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... structure, like pull-apart basin, now looks like half-graben (Fig. 2a). This structure is bounded by the general systems of north-western and sub-latitude faults. The first of them correspond to the ISZ and the NEF zone formed at the stage of formation of the Altai convergent margin, since they control the emplacement of two volcanic belts (Fig. 2c). According to geological mapping at a scale of 1:200,000 (Murzin et al., 2001), these volcanic belts in the sides of the Alei structure were formed synchronously; although it has not yet been determined whether the compositions of volcanic rocks from these belts are identical. The formation of feathering sub-latitudinal faults ...
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... rhyolites. The first stage total rock thickness is ~400 m. The second pronounced stage or so-called "Givetian -Frasnian rhyolite-basalt flash" corresponded to the clear mode of extension, and the formation of the so-called Shipunikha rift-like structure in the rear part of the NW Rudny Altai, accompanied by fractured effusions of basalts (Fig. 2a). This stage includes three volcanic rhythms, generally called the third, fourth and fifth. Accordingly, the third rhythm covers the period of formation of the varied stratified strata, consisting of lava, lava-breccia, tuffs and felsic ignimbrites composition (Fig. 3). The fourth rhythm is reflected by the eruptions of basalt flows ...
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... MS-rhyolites were collected mainly from the NE volcanic belt (Fig. 2) including several volcanic centers located in a chain on a direction NW-SE: Voronezh, Karaulny, Butochny and Sadovushka ( Fig. 4a-h). Butochny and Sadovushka were originally parts of a single volcanic center, but now they are separated by the local pull-apart structure inside the Sipunikha rift (Fig. 2). The volcanic center Kryuchki, ...
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... collected mainly from the NE volcanic belt (Fig. 2) including several volcanic centers located in a chain on a direction NW-SE: Voronezh, Karaulny, Butochny and Sadovushka ( Fig. 4a-h). Butochny and Sadovushka were originally parts of a single volcanic center, but now they are separated by the local pull-apart structure inside the Sipunikha rift (Fig. 2). The volcanic center Kryuchki, the only exposure of MS-rhyolite in the SW volcanic belt, was also collected for this study (Fig. 2). Subvolcanic intrusions occur as stock-, sill-and dike-like bodies localized inside the Late Emsian -Early Givetian stratified volcanogenic-sedimentary deposits of the first stage (Fig. 3). A large number ...
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... Karaulny, Butochny and Sadovushka ( Fig. 4a-h). Butochny and Sadovushka were originally parts of a single volcanic center, but now they are separated by the local pull-apart structure inside the Sipunikha rift (Fig. 2). The volcanic center Kryuchki, the only exposure of MS-rhyolite in the SW volcanic belt, was also collected for this study (Fig. 2). Subvolcanic intrusions occur as stock-, sill-and dike-like bodies localized inside the Late Emsian -Early Givetian stratified volcanogenic-sedimentary deposits of the first stage (Fig. 3). A large number of rhyolites have experienced significant brittle deformations, and are quite often subject to secondary alterations, including ...
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... separated in one batch with the zircons from R2-rhyolite, we assume that clogging of this sample could occur. If we calculate the total weighted average age obtained for all zircon grains from this sample, it yields a value of ~384 Ma, which contradicts the stratigraphic data, since at this point there was a volcanic pause in the NW Rudny Altai (Fig. 3; Murzin et al., 2001). On the other hand, the Phase 1 1 1 1 1 1 2 2 2 3 3 3 3 № ms-1/2 ms-1/3 ms-12 ms-14/1 ms-14/2 ms-14/3 ms-13/1 ms-30/2 ms-16 ms-17 ms-19 ms-22 ms-32 Sr 33 36 35 129 158 112 41 96 50 79 144 69 obtained variations of 206 Pb/ 238 U isotopic ages are still within the accuracy of the LA-ICP-MS method used. Zircon grains of sample №MS-8 ...
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... relationships between Nb, Y, Zr and Ce, and ratios of Ga/Al (1.26-3.52), and Zn (9-187 ppm) concentrations, show that the R1-rhyolite has continuous transitional characteristics between the OGT (unfractionated M-, I-and S-granite) and A-type felsic rocks ( Fig. 12a- f; Whalen et al., 1987). In contrast, the R2-and R3-rhyolites are marked only in the OGT-field, since the total Nb, Y, Zr and Ce (119-242 ppm), and Ga/Al (0.51-1.39) values; and Zn (52-171 ppm) contents are relatively low. In the Nb vs. Y and Rb vs. Y + Nb tectonic discrimination diagrams ( Pearce et al., 1984), all of the rhyolites are ...
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... marked only in the OGT-field, since the total Nb, Y, Zr and Ce (119-242 ppm), and Ga/Al (0.51-1.39) values; and Zn (52-171 ppm) contents are relatively low. In the Nb vs. Y and Rb vs. Y + Nb tectonic discrimination diagrams ( Pearce et al., 1984), all of the rhyolites are transition between volcanic-arc (I-type) and within-plate (A-type) fields ( Fig. 12g-h; Whalen et al., 1987). Although the variations in Rb are coherent with K 2 O, we neglected it in this case because the reason for that the rhyolites compositions plot on the border between the fields of normal arcrelated and within-plate felsic magmas is due to Y + Nb (32-92 ppm) and Ta + Nb (7-15 ppm) abundances. All rhyolites possess ...
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... K 2 O, we neglected it in this case because the reason for that the rhyolites compositions plot on the border between the fields of normal arcrelated and within-plate felsic magmas is due to Y + Nb (32-92 ppm) and Ta + Nb (7-15 ppm) abundances. All rhyolites possess low Rb (b200 ppm) contents, which is incompatible with a syn-collision setting (Fig. 12h). Consequently, some of the R1-rhyolite bear the distinctive geochemical signature of A-type felsic magmas, such as: (i) total enrichment in Zr, Nb, Y and Ce (N350 ppm), Zr (N250 ppm), and high Ga/Al values (N2.6; Whalen et al., 1987). In general, if we consider all MSrhyolites, they have transitional geochemical characteristics that ...
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... characteristics that resemble those of felsic rocks of the subduction-related extension geodynamic settings. However, this magmatism was unlikely to be associated with the rebound of the oceanic plate following slab break-off and extensional detachment of subduction orogen, like the Cordillera of North America (Whalen and Hildebrand, 2019); Fig. ...
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... the geochemical characteristics of MS rhyolites, their initial geochemical type is still difficult to identify. As suggested to us Prof. Bruno Scaillet "All the types discussed here are metaluminous". (i) Obviously, the parental magmas of the MSrhyolites were hardly peralkaline in nature, as was observed from their Zr/Ti and Nb/Y ratios (Fig. 10а and Fig. 12j). (ii) It is also unlikely that these magmas were peraluminous type, because they have Atype evolutionary trend (Fig. 12f), and are clearly different from highly fractionated S-and I-type granites, that would increase their Ga/Al ratios при crystal differentiation ( Wu et al., 2017). (iii) As discussed below, the R2-and R3-rhyolites ...
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... to us Prof. Bruno Scaillet "All the types discussed here are metaluminous". (i) Obviously, the parental magmas of the MSrhyolites were hardly peralkaline in nature, as was observed from their Zr/Ti and Nb/Y ratios (Fig. 10а and Fig. 12j). (ii) It is also unlikely that these magmas were peraluminous type, because they have Atype evolutionary trend (Fig. 12f), and are clearly different from highly fractionated S-and I-type granites, that would increase their Ga/Al ratios при crystal differentiation ( Wu et al., 2017). (iii) As discussed below, the R2-and R3-rhyolites are somewhat resemble high-silica residual and non-equilibrium melts associated with A-type magmas ( Barboni and Bussy, ...
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... 12f), and are clearly different from highly fractionated S-and I-type granites, that would increase their Ga/Al ratios при crystal differentiation ( Wu et al., 2017). (iii) As discussed below, the R2-and R3-rhyolites are somewhat resemble high-silica residual and non-equilibrium melts associated with A-type magmas ( Barboni and Bussy, 2013); Fig. 12f. In general, this indicates that the parental magmas of the MS-rhyolites should have been ...
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... show even greater geochemical affinity to the extensional rhyolites of the bimodal association of the Coastal Range in the Central Chile, related to Late Triassic intra-continental rifting in the Pacific Gondvana margin ( Fig. 13b; Morata et al., 2000). There is also a geochemical similarity to some of the bimodal-type rhyolites of Taupo Volcanic Zone, New Zealand (Deering et al., 2011), although the latter are mostly characterized by more depleted concentrations of MREEs and HREEs (Fig. 13b). As for the R2-and R3-rhyolites, it have the so-called seagull-like form of REE-patterns, which, in the simplifying assumptions, resemble those of some fractionated granites (FG) and A 2 -type granites attributed to post-orogenic extension tectonic setting ( Chappell and White, 1992;King et al., 1997;Chappell, 1999). ...
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... and A 2 -type granites attributed to post-orogenic extension tectonic setting ( Chappell and White, 1992;King et al., 1997;Chappell, 1999). However, all of the MS-rhyolites are clearly distinguished from post-orogenic granites, by a general depletion in REEs, lower HFSEs (e.g. Nb ~ 7-13 ppm; Th ~ 5-10 ppm) contents, and less pronounced Eu anomaly (Fig. 12c, d), for example, if we compare them with A 2 -granite from Southern Altai Range, China (Shen et al., 2011). By the same geochemical characteristics, they differ from bimodal-type rhyolites associated with initial rifting, as in Miocen ridge-subduction-related California-type environments (Johnson and O'Neil, 1984;Cole and Basu, 1992). ...
Citations
... At the end of the Early Devonian-beginning of the Middle Devonian (since 395 Ma), the tectonomagmatic activity covered the western margin of the Altai-Sayan area, which was involved in convergence processes. This resulted in an active continental margin (Rotarsh et al., 1982;Zonenshain et al., 1990;Vladimirov et al., 2003;Windley et al., 2007;Kruk et al., 2008;Pirajno, 2010;Cai et al., 2011;Kuibida et al., 2020;Kozakov et al., 2022). Its formation was caused by the subduction of the Chara oceanic plate beneath the early Paleozoic orogen and the formation of a marginal volcanoplutonic belt along the convergent boundary. ...
The Early Devonian Altai–Sayan rift system (ASRS) has spread to the structures of East and West Sayan, Kuznetsk Alatau, and Mongolian Altay. Its largest fragments are the Tuva, Delyun–Yustyd, Kan, Agul, and Minusa basins as well as depressions in north-western Mongolia. The paper summarizes the geologic, geochemical, and Sr–Nd isotope characteristics of the ASRS mafic rocks represented by nappes of moderately alkaline and alkali basalts and their subvolcanic and intrusive rock analogues. They are present in all magmatic associations and are divided into low-Ti (TiO2 = 0.2–2.2 wt.%) and high-Ti (TiO2 = 2.2–4.3 wt.%) subgroups. These rocks are characterized by wide variations in Sr isotope characteristics (εSr(T) = –16 to +30). High-Ti mafic rocks are common at the southern segment of the ASRS; they show a weak positive Ta–Nb anomaly (La/Nb = 0.8–1.1) and are relatively enriched in LREE ((La/Yb)N = 6–14) and radiogenic Nd (εNd(T) = 3.8–8.7). Low-Ti varieties are confined to the northwestern segment of the ASRS; they are enriched in Ba but depleted in Th, U, Nb, Ta (La/Nb = 1.2–2.2), Zr, Hf, LREE ((La/Yb)N = 3–7), and radiogenic Nd (εNd(T) = 2.0–6.0). Taking into account the existence of different terranes, which were combined in the structure of the Altai–Sayan folded area during accretion (ca. 500–480 Ma), we propose a model suggesting different environments of magma formation at the southern and northwestern segments of the ASRS and the relationship of magmatism with a mantle plume within the ASRS. In composition the plume corresponds to the sources of high-Ti magmas. The effect of the melted lithospheric mantle of different compositions beneath different groups of terranes led to the observed isotope-geochemical heterogeneity of mafic rocks within the ASRS, in particular, the absence of high-Ti mafic rocks from the Minusa basin.
... This age falls in the range of 408-372 Ma (rounded to 1 Ma), which according to the present-day international chronostratigraphic chart (Cohen et al., 2019), corresponds to the ore-bearing area of the Devonian volcanosedimentary sequence. These intervals within error are consistent with recently obtained U-Pb zircon dates on three rhyolite samples of Rudny Altai (391-378 Ma) (Kuibida et al., , 2020. Presented intervals are sufficiently wide (15-20 Ma) and could be considered only as a rough estimate, indicating the Early-Middle Devonian age of the deposits. ...
... Moreover, the contents of metallic elements (Cu and Zn) that are easy to be carried by the fluids also remain unchanged except for some outliers (Appendix Fig. A1gh). Different from the above elements, the REEs and HFSEs (high field strength elements) are generally immobile and are insensitive to alteration and metamorphism (Polat et al., 2002;Kuibida et al., 2020). Among them, zirconium is generally believed to be the most immobile in different types of alternation and varied grades of metamorphism. ...
... The sea gull REE pattern (Fig. 9c), due to deep negative Eu anomaly, is a characteristic feature of hot-dry-reduced magmas with relatively low oxygen fugacity, that were formed in the terrains of mantle upwelling (i.e. hotspots and continental rifts ;Christiansen 2005;Bachmann and Bergantz, 2008;Christiansen and McCurry, 2008;Deering et al., 2010;Frost et al., 2016;Kuibida et al., 2020;Szemerédi et al., 2020;El-Bialy et al., 2022). In all analyzed volcanics there is interrelation between the Eu anomaly and the Ba and Sr concentrations that reveals that the strong negative Eu anomalies are mostly associated with the low Ba and Sr concentrations indicating extreme alkali feldspar fractionation. ...
... The very low Ba/Sr and Sr/Y ratios (0.05-314 and 0.07-1.64, respectively; Table 2), the presence of strong negative Eu-anomalies and the HREEs are not depleted as the Yb and Lu are 80-150 times chondrite, indicating that JATV formed at relatively low oxygen fugacity (i.e., hot-dry-reduced magma; Bachmann and Bergantz, 2008;El-Bialy and Hassen, 2012;Frost et al., 2016;Kuibida et al., 2020;Szemerédi et al., 2020). The hot-dry magma with its characteristics sea-gull REEs pattern due to the steep negative Eu anomaly and enriched HREEs (Fig. 9c), suggest that the JATV magma source was garnet-free (Laurent et al., 2014;Wilson, 1989). ...
... (1) Middle Late Paleozoic Rudny-Altai zone that formed on the Siberian active margin as a result of the subduction of Ob-Zaisan oceanic plate [9][10][11]; ...
The Great Altai region, located at the boundary of Russia, Mongolia, China, and Kazakhstan, belongs to the system of the Central Asian Orogenic Belt. It has undergone a long complex geological and metallogenic history. Extremely rich resources of base, precious, and rare metals (Fe, Cu, Pb, Zn, Ag, Au, Li, Cs, Ta, Nb, REE, etc.) maintain developed mining and metallurgical industry, especially in East Kazakhstan, which is the key metallogenic province. The East Kazakhstan province comprises the Rudny Altai, Kalba-Narym, West-Kalba, and Zharma-Saur metallogenic belts, each having its typical mineralization profiles and deposits. The reconstructed geodynamic and metallogenic history of the Great Altai province, along with the revealed relationships between tectonic settings and mineralization patterns, allowed us to formulate a number of geodynamic, structural, lithostratigraphic, magmatic, mineralogical, and geochemical criteria for exploration and appraisal of mineral potential in Eastern Kazakhstan. Geodynamic criteria are based on the origin of different mineralization types in certain geodynamic settings during the Late Paleozoic–Early Mesozoic orogenic cycle. Structural criteria mean that the location of base-metal deposits in Rudny Altai, gold deposits in the West Kalba belt, rare and base metals in the Kalba-Narym and Zharma-Saur zones is controlled by faults of different sizes. Lithostratigraphic criteria consist of the relation of orebodies with certain types of sedimentary or volcanic-sedimentary rocks. Magmatic criteria are due to the relation between mineralization types and igneous lithologies. Mineralogical and geochemical criteria include typical minerals and elements that can serve as tracers of mineralization. The joint use of all these criteria will open new avenues in prospecting and exploration at a more advanced level.
... The Altai-Mongolian Terrane is bounded with the Rudny Altai farther south by a sinistral strike-slip fault of the North-East Fault (Fig. 1b). The Rudny Altai has been interpreted to be a back-/intra-arc extensional basin that was developed along the southern margin of the Altai-Mongolian Terrane (Buslov et al., 2004;Lobanov et al., 2014;Kuibida et al., 2020). The oldest rocks in the Rudny Altai are Silurian to Devonian meta-sedimentary rocks (metasandstones, schists, and phyllites), which are overlain by Devonian to Carboniferous rhyolite-basalt lava, volcanic breccia, tuff, conglomerate, sandstone and minor limestone (Buslov et al., 2001;Buslov et al., 2004;Kruk et al., 2011;Lobanov et al., 2014). ...
... The Altai-Mongolian Terrane, the Rudny Altai, and the Irtysh-Zaisan Complex in eastern Kazakhstan are voluminously intruded by late Paleozoic granitoids ( Fig. 1b; Glorie et al., 2012;Khromykh et al., 2016;Kuibida et al., 2019Kuibida et al., , 2020Zhang et al., 2020;Kotler et al., 2021). The Devonian to Carboniferous magmatism was considered to be associated with the northward subduction of the Ob-Zaisan oceanic plate (Buslov et al., 2004;Safonova, 2014;Kuibida et al., 2020;Zhang et al., 2020), while the Permian intrusions were likely related to the collision of the Windley et al., 2007;Li et al., 2018;and Hu et al., 2020). ...
... The Altai-Mongolian Terrane, the Rudny Altai, and the Irtysh-Zaisan Complex in eastern Kazakhstan are voluminously intruded by late Paleozoic granitoids ( Fig. 1b; Glorie et al., 2012;Khromykh et al., 2016;Kuibida et al., 2019Kuibida et al., , 2020Zhang et al., 2020;Kotler et al., 2021). The Devonian to Carboniferous magmatism was considered to be associated with the northward subduction of the Ob-Zaisan oceanic plate (Buslov et al., 2004;Safonova, 2014;Kuibida et al., 2020;Zhang et al., 2020), while the Permian intrusions were likely related to the collision of the Windley et al., 2007;Li et al., 2018;and Hu et al., 2020). The inset image shows the location of the CAOB (after Jahn, 2004). ...
To unravel when, where, and how multiple arc systems were amalgamated is crucial for understanding the accretion processes of the Central Asian Orogenic Belt. Here we focus on the collision of the Siberian margin and the Kazakhstan collage along the Char Shear/Suture Zone in eastern Kazakhstan. We conducted U–Pb dating and Hf isotope analysis for detrital zircons of clastic rocks across the collisional zone of the Siberian margin (the Irtysh-Zaisan Complex) and the Kazakhstan collage (the Zharma-Saur Arc and the Char Zone). Our results show that the Irtysh-Zaisan Complex carries abundant early Paleozoic detrital zircons and minor Precambrian zircons, but there is a lack of such zircon populations in the Zharma-Saur Arc and the Char Zone. Devonian to Carboniferous detrital zircons appear in all sampling tectonic units, in which εHf(t) values of Carboniferous zircons from the Zharma-Saur Arc and the Char Zone are characterized by a narrow range (∼10-17) that is different from a relatively wider range of εHf(t) values of ∼5-18 for the Carboniferous zircons in the Irtysh-Zaisan Complex. The distinct sedimentary provenances of the Irtysh-Zaisan Complex and the Zharma-Saur Arc/Char Zone confirm that their tectonic boundary lies along the Char Shear Zone in eastern Kazakhstan. As the Late Carboniferous sedimentary rocks from the Zharma-Saur Arc and the Char Zone do not receive detritus from the Siberian margin, we consider that the Ob-Zaisan Ocean between the Siberian margin and the Kazakhstan collage was closed later than the deposition of these sedimentary rocks (<321 Ma).
The Rudny Altai metallogenic province, which is concordant to the structures of the eponymous terrane and located in the Central Asian orogenic belt (CAOB), is one of the largest volcanic massive sulfide (VMS) provinces in the world. Lead isotopic composition of galena (61 samples in total) was measured for the first time with high accuracy (±0.02%, SD) for 20 sulfide base metal deposits representing the dominant Kuroko type in the Rudny Altai. They are enclosed in the Early–Middle Devonian volcano-sedimentary sequence in association with volcanic rocks of the bimodal basalt-rhyolite series. We studied the large and superlarge deposits of this type: Ridder-Sokol’noe, Tishinskoe, Novo-Leninogorskoe, Zyryanovskoe, Zmeinogorskoe, and Korbalikha. In the province, the isotope ratios 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb vary within narrow limits. At average values of 206Pb/204Pb = 17.820, 207Pb/204Pb = 15.517 and 208Pb/204Pb = 37.669, the root mean square variations (variation coefficient, %) are 0.22, 0.038 and 0.063% respectively. Even more homogeneous composition is observed within ore districts of the province (0.054, 0.012 and 0.020%) and especially within deposits (0.025, 0.010 and 0.013%), where the scale of variations of lead isotope ratios reaches their measurement error (±0.02%). The lead isotopic composition in the province shows no isotopic “signatures” of juvenile (asthenospheric) origin. The evolutionary characteristics of the lead source (its depletion in uranium, the old model Pb-Pb age, and moderate values of the µ2 parameter) together with the persistent isotopic composition allow us to regard the lithospheric mantle consisting of metasomatized and recycled rocks as its source. This source was of regional significance, chemically (U-Th-Pb) and isotopically (Pb-Pb) homogeneous, and common for all deposits. Among other CAOB terranes, including the Chinese Altai, the 206Pb, 207Pb and 208Pb isotopes in the ore lead of the Rudny Altai terrane have the least radiogenic composition. The previously noted (Chiaradia et al., 2006) systematic decrease of radiogenic isotope content in the lead of ores and rocks of the CAOB terranes from the southwest to the northeast correlates with a decrease in the lower crustal contribution in the same direction in their composition, where fragments and blocks of Precambrian crust are also involved. The peculiarity of the Pb isotopic composition of the Rudny Altai terrane is largely determined by the absence of Precambrian crustal blocks in its composition.
In the Russian Rudny Altai, four stages of magmatism are distinguished in the age range from the end of the Early Devonian to the Middle Carboniferous. (1) The earliest Melnichnaya-Sosnovskaya dacite-rhyolite volcanic complex (D1-2) includes effusive-pyroclastic strata of the Melnichnaya and Sosnovskaya formations and associated subvolcanic formations. Mass U-Pb dating of zircon from volcanics showed an Eifelian age of 392-388 Ma. (2) Kamenevsky basalt-dacite-rhyolite volcanic complex (D2-3) combines effusive-pyroclastic strata of the Davydov and Kamenev formations with comagmatic subvolcanic and vent formations. The U-Pb age of the Kamenevsky complex of 384-364 Ma. The volcanic rocks of the Kamenevsky complex are comagmatic with the intrusive formations of the Late Devonian Zniznogorsk gabbro-granite-leucogranite complex. (3) The Pikhtovsky basalt-dacite-rhyolite volcanic complex (D3-C1) includes effusive and pyroclastic formations of the Pikhtovsky Formation and comagmatic subvolcanic intrusions. The U-Pb age of the Pikhtovsky complex of 362-345 Ma. (4) The Volchikhinsky gabbro-tonalite-granite hypabyssal complex (C1-2) forms two branches of linearly located intrusions in the northwestern direction with an age of 339-319 Ma. The buried Panfilov andesite-dacite-rhyolite volcanic complex and the comagmatic Rubtsovsky gabbro-tonalite-granite hypabyssal complex, developed in the Rubtsovskaya depression on the Rubtsovskaya uplift, have not been characterized by isotope dating.
The Tuvinian trough is one of the large grabens of the rift system formed in the Devonian-Carboniferous in the eastern part of the Altai-Sayan fold area. Based on the results of comprehensive studies, the age was refined, and the geochemical features of igneous rocks formed during two stages of tectonic and magmatic activity within the Tuvinian trough were studied. In the Early Devonian (397 Ma, Emsian), at the stage of the initiation of the Tuvinian trough in the stretching setting, the volcanic and subvolcanic rocks of the Kendei Formation formed, which make a bimodal series. The Early Devonian igneous rocks of mafic composition have geochemical features of both intraplate (low values of Mg#, high contents of K 2 O (up to 2.9 wt.%) and TiO 2 (up to 2.2 wt.%), and enrichment in LREE relative to HREE) and suprasubductional (enrichment in Pb and Sr and depletion in Ta and Nb) formations and are characterized by high values of ε Nd (T) (+5.9 to +8.0). They are assumed to have formed from a mixed source including the depleted mantle and components modified by subduction. The Early Devonian felsic volcanic rocks, which are the extreme member of the bimodal sequence, also combine the geochemi cal features of rocks of intraplate (high Fe, low Sr, P, and Ti contents, Zr and Hf enrichment) and island arc (Ta and Nb depletion) origin. These rocks with ε Nd (T) values from +4.0 to +7.0 resulted from the melting of a heterogeneous source corresponding in composition to the lower continental crust. In the Middle Devonian-early Carboniferous (390-350 Ma), the Tuvinian rift trough evolved into a mature stage, at which the mafic rocks of the Torgalyk complex were intruded. The Middle Devonian-early Carboniferous mafic rocks are similar in isotope and geochemical characteristics, including the Nd isotopic composition (ε Nd (T) = +6.7), to the Early Devonian formations. In contrast to the Early Devonian rockes, the magmas for the Middle Devonian-early Carboniferous mafic rocks were generated a relatively homogeneous mantle source without significant metasomatic transformations, the features of which are better manifested in the Kendei rocks.
Anorogenic magmatism in the northern Arabian-Nubian Shield occurred during a long-lasting crustal extension event (<580 Ma), which succeeded the formation of the Pan-African orogenic belt in NE Africa and Arabia. Late Neoproterozoic anorogenic felsic volcanic-subvolcanic rocks, along with post-collisional granitoid suites, are exposed in the Gabal Abu Durba mountain range along the eastern flank of the Gulf of Suez in Sinai. These rocks include granite and rhyolite porphyries, metaluminous to weakly peralkaline with distinct potassic alkaline and ferroan affinities. Major and trace element characteristics such as K2O/MgO >16, total alkalis >8.5 wt.%, (K2O + Na2O)/CaO >10, agpaitic index (NK/A) >0.85 and Zr (>250 ppm), Nb (>20 ppm), Y (>80 ppm), Zn (>100 ppm) and Ce (>100 ppm), and 10,000 × Ga/Al >2.6 and [Zr + Nb + Y + Ce] >350 ppm are suggestive of an A-type granite genesis. Zircon U-Pb dating of two representative samples returned crystallization ages of 569 ± 2.6 Ma and 561.7 ± 3.2 Ma for granite and rhyolite porphyries, respectively. The melting temperatures estimated at 997–1020°C are consistent with high-temperature liquidus conditions. Fractional crystallization, coupled with less significant crustal assimilation, was likely the main mechanism of formation of these rocks from a common primitive asthenospheric mantle-derived trachytic magma in an anorogenic intra-plate setting. The A-type alkali granite and rhyolite porphyries of Gabal Abu Durba are manifestations of mantle upwelling and lower crust underplating in the late Ediacaran anorogenic stage. These felsic subvolcanic intrusions (≈ 569–562 Ma) along with their volcanic counterparts constitute a new unmatched rock unit that most probably represents the last chapter of the anorogenic magmatism in the Neoproterozoic Arabian-Nubian Shield crust before the beginning of Phanerozoic era.
