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I. V. Buchko A. E. Izokh E. B. Sal’nikova A. A. Sorokin A. B. Kotov S. Z. Yakovleva 《Petrology》2007,15(3):264-274
The Veselki peridotite-websterite-gabbronorite massif was dated by U-Pb zircon method at 154 ± 1 Ma. This is the first Late Jurassic date obtained for ultramafic-mafic massifs in the eastern part of the Selenga-Stanovoy superterrane bounding the southeastern margin of the Siberian craton. The mineralogical specifics of the massif is expressed in the presence of three-pyroxene assemblage [bronzite-pigeonite-augite (diopside)] and exsolution lamellae of Cr-spinel and Cr-magnetite in Fe-Cr picotite and suggests unstable crystallization at shallow depths. Geochemical similarity between the Upper and Lower series attests to their genetic relation through intrachamber differentiation. The massif was generated from a highly evolved melt, as is seen from the LREE enrichment (La/Yb)N = 3.89–30. Plagioclase varieties display a weak positive Eu anomaly (Eu/Eu* = 1.1–1.25), whereas other rocks have an insignificant negative Eu anomaly (Eu/Eu* = 0.85–0.97). Model calculations show that parental melt was close to subalkaline picrite, which evolved along two fractionation trends into dunites and subalkaline gabbroids and monzodiorites. 相似文献
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I. V. Buchko A. A. Sorokin E. B. Sal’nikova A. B. Kotov A. M. Larin A. P. Sorokin S. D. Velikoslavinskii S. Z. Yakovleva 《Stratigraphy and Geological Correlation》2008,16(4):349-359
The results of geochemical and geochronological study of the Kengurak-Sergachi gabbroanorthosite massif in the Selenga-Stanovoi superterrane, southern frame of the Siberian craton, are presented. According to geochemical peculiarities, the massif rocks are close to the autonomous “massif-type anorthosite.” The massif age corresponds to 1866 ± 6 Ma based on the results of U-Pb zircon dating. The Kengurak-Sergachi massif was intruded most likely in post-collision epoch concurrently to formation of the South Siberian giant post-collision magmatic belt (1.87–1.84 Ga) extending along the southwestern flank of the Siberian craton. 相似文献
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Complex mineralogical, geochemical, and geochronological studies of the gabbroids from the Dzhigdinskii Massif located in the western part of the Dzhugdzhur–Stanovoy Superterrane are performed. It is established that the age of the rocks from the Dzhigdinskii Massif is Middle Triassic (244 ± 5 Ma), rather than Early Archean, as was previously assumed. The age of the Dzhigdinskii Massif is close to the age of the formation of the other Triassic gabbroid massifs, such as the Amnunaktinskii (~240 Ma), Lukindinskii (~250 Ma), and Luchinskii (~248 Ma) in the southeastern environ of the North Asian Craton. One of the stages in the formation of the Selenga–Vitim volcanoplutonic belt falls in this period as well. This indicates that the Selenga–Vitim volcanoplutonic belt, along with the granitoids and volcanic rocks, is composed of ultrabasic–basic and basic massifs and that this belt is superposed on the structures of the Selenga–Stanovoy Superterrane, as well as on the western part of the Dzhugdzhur–Stanovoy Superterrane. The gabbro, gabbro–diorite, and series of gabbro and gabbro–diorite with high sodic alkalinity from the Dzhigdinskii Massif show obvious geochemical features of duality, including combination of intraplate and super-subduction origin. In this relation, we can assume that the origin of the gabbroids of the Dzhigdinskii Massif is related to the detachment of the oceanic lithosphere and its subduction into the mantle with the formation of an “asthenospheric window.” 相似文献
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The Chek-Chikan Massif is a typical representative of basic magmatism, which is widely spread within the Dzhugdzhur-Stanovoi
superterrane. The massif consists of gabbronorites, amphibole gabbros, gabbroanorthosites, and anorthosites.
The geochemical similarity of the gabbronorites, amphibole gabbros, and anorthosites suggests their genetic link and allows
us to consider them as products of intrachamber differentiation. The main geochemical peculiarity of this rock association
is the high degree of the melt fractionation. The rocks of the considered massif are enriched in large ion lithophile elements
such as Sr (424–1018 ppm) and Ba (50–754 ppm) and have moderate to low contents of such high-field strength elements as Nb
(1–17 ppm), Hf (0.4–1.0 ppm), and Th (0.05–1.14 ppm). According to the model calculations, the initial melt had a basaltic
composition and crystallized at a temperature of ∼1180 °C and pressure up to 4 kbar. The U-Pb zircon age of the massif is
203 ± 1 Ma. The geochemical peculiarities of the massif and its confinement to the northern framing of the eastern segment
of the Mongol-Okhotsk fold belt make it possible to presume that its formation was related to either the activity of the Siberian
plume, to one of the stages of closure of the Mongol-Okhotsk paleoocean in the rear part of subduction zone, or to the slab
break off. 相似文献
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I.V. Buchko A.A. Sorokin E.B. Sal''nikova A.B. Kotov A.M. Larin A.E. Izokh S.D. Velikoslavinsky S.Z. Yakovleva 《Russian Geology and Geophysics》2007,48(12):1026-1036
We present new data on the age and geochemistry of the Veselyi and Petropavlovsk ultramafic-mafic massifs of the Selenga-Stanovoy (West Stanovoy) superterrane on the southeastern framing of the North Asian craton. The massifs are composed of rocks of peridotitewebsterite-gabbro and peridotite-gabbro-monzodiorite associations, respectively. The latter combine normal, subalkalic, and alkaline rocks and thus are of diverse composition: from ultrabasites and pyroxenites through gabbroids to monzodiorites. The U-Pb zircon age of these massifs is 154 ± 1 and 159 ± 1 Ma, respectively, which permits them to be referred to as the youngest rocks of ultramafic-mafic complexes on the southern framing of the North Asian craton. The rocks of the studied massifs are enriched in LILE (K, Rb, Sr, Ba, LREE) and are depleted in HFSE (Zr, Nb, Hf, Ta). These rocks formed, most likely, in the rear of subduction zone or in the setting of the subducting-slab detachment. 相似文献
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I. V. Buchko A. A. Sorokin A. V. Ponomarchuk A. V. Travin V. A. Ponomarchuk 《Doklady Earth Sciences》2017,472(1):62-66
The Elna Cu(Au)–porphyry deposit is one of the typical ore objects in the northeastern margin of the Argun superterrane facing the Mongolia–Okhotsk foldbelt. Mineralization includes zones of argillization with fine quartz veins in granodiorite of the Elna massif. The geochronological 40Ar/39Ar studies of hydrothermal near-ore metasomatites and magmatic rocks of the deposit show that the age of host granitoids is 126 ± 2 Ma, which corresponds to the upper age boundary of granitoids from the Burinda Complex, whereas the age of overprinted hydrothermal processes is 122–117 Ma. The age of mineralization correlates well with the age of the thermal event in East Asia. An intense stage of magmatism including both volcanic and intrusive forms occurred in this period. 相似文献
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I. V. Buchko A. A. Sorokin A. A. Rodionov N. M. Kudryashov 《Doklady Earth Sciences》2018,479(2):448-451
U–Pb ID–TIMS zircon analyses of the Dzhigda gabbro–gabbrodiorite Massif (Ilikan block in the southwestern part of the Dzhugdzhur–Stanovoi superterrane) have been carried out. The results demonstrate that the formation of the massif at 244 ± 5 Ma corresponds to one of the stages of formation of the Selenga–Vitim volcano–plutonic belt. The latter stretches along the southeastern margin of the North Asian Craton along its border with the Mongol–Okhotsk fold belt. This indicates that the Selenga–Vitim volcano–plutonic belt along with granitoids and volcanics comprises Permian–Triassic massifs and that this belt is superimposed onto structures of not only the Selenga–Stanovoi terrane but also the Dzhugdzhur–Stanovoi terrane. 相似文献