Geochemical evidence for the ophiolitic nature of the gabbros,gabbroanorthosites, and ultramafic rocks of the Gerbikan fragment of the Baladek Massif of the southeastern framing of the North Asian craton     

A. A. Sorokin  I. V. Buchko  A. B. Kotov  S. D. Velikoslavinsky 《Russian Journal of Pacific Geology》2010,4(5):418-428

The Baladek Massif represents a tectonic block located at the boundary between the SE framing of the North Asian craton and the fold structures of the Galam terrane of the Mongol-Okhotsk fold belt. According to the existing concepts, the rocks of this massif are regarded as Precambrian complexes of the aforementioned craton. This paper reports the results of studying the fragment of the Baladek Massif in the Gerbikan River basin. New geochemical data obtained on the gabbros, gabbroanorthosites, and ultramafic rocks testify to their similarity with typical ophiolite complexes. An underlying complex of metamorphic ultrabasic rocks, a layered complex of pyroxenites and “cumulate” gabbros, gabbroanorthosites, and a complex of isotropic gabbros were distinguished within this fragment. It is highly possible that the basic volcanic rocks and jaspers of the Silurian-Lower Devonian sequences of the Galam segment of the Mongol-Okhotsk fold belt also belong to the inferred ophiolite complex.  相似文献   

First data on the noble metal geochemistry of the rocks from the gabbro-anorthosite massifs of the Kalar group     

I. V. Buchko  A. A. Sorokin 《Russian Journal of Pacific Geology》2010,4(6):461-469

This paper addresses the geochemical features of the noble metal disseminated sulfide and Timagnetite mineralization in the rocks of the Kalar group of autonomous gabbro-anorthosite massifs. The investigations suggest that this mineralization was formed in two stages. The first stage is related to the gabbroanorthosites proper and may be promising for low-sulfide PGE mineralization as well as PGE-bearing Ti-magnetite mineralization, while the second stage is linked to the ultrabasic intrusions associated with copper-nickel or chromite mineralization accompanying by PGE. The horizons of low-sulfide mineralization in the gabbro-anorthosites and copper-nickel mineralization in the dunite-pyroxenites are characterized by the Pd predominance over Pt, while the Cr-bearing and Ti-magnetite ores show the Pt predominance over Pd.  相似文献   

Late paleozoic gabbroids of the Lesser Khingan terrane of the eastern Central-Asian fold belt: Age, geochemistry, and tectonic setting     

I. V. Buchko  A. A. Sorokin  N. M. Kudryashov 《Russian Journal of Pacific Geology》2013,7(3):189-198

This paper considers the results of mineralogical, geochemical, and geochronological studies of leucogabbroids of the Karagai Massif located within the Lesser Khingan superterrane of the Central Asian fold belt. The main features of the rock-forming minerals of the gabbroids are the high calcium content of the clinopyroxene corresponding in composition to diopside-salite (Wo_48–51En_33–39Fs_11–16) or augite (Wo_22–35En_46–47Fs_18–33), the high basicity of the plagioclase (An_90–92), and the presence of primary magmatic magnesian hornblende. The age of the massif was determined by U-Pb zircon dating as 257 ± 1 Ma. The compositional peculiarities of the gabbroids indicate that they were most probably formed in island-arc or active continental margin settings. With allowance for the existing geodynamic reconstructions and the data obtained in the present study, the formation of the Late Paleozoic gabbroids of the Karagai Massif was presumably related to the final stages of the subduction processes that preceded the collapse of the terranes of the eastern Central Asian fold belt.  相似文献   

<Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar age of gold mineralization of the Malomyr deposit (eastern part of the Mongolian–Okhotsk foldbelt)     

A.?A.?SorokinEmail author  A.?V.?Ponomarchuk  I.?V.?Buchko  A.?V.?Travin  V.?A.?Ponomarchuk 《Doklady Earth Sciences》2016,466(1):64-69

Reliable age estimation was obtained originally in this study for gold mineralization of the Malomyr deposit (the eastern part of the Mongolian–Okhotsk foldbelt), which is one of the most well-known deposits in the Russian Far East. The data obtained show that the age of hydrothermal process that resulted in the formation of the Malomyr deposit may be estimated as ～133–132 Ma. Data on magmatism of the same age within the considered region are absent. In the opinion of the authors, mobilization, redistribution of the ore material, and the formation of the Malomyr deposit were mostly controlled by dislocation processes accompanied by hydrothermal activity, which is supported by the results of structural studies.  相似文献   

Age and geodynamic setting of the formation of the dess gold-silver deposit (North Stanovoi metallogenic zone,southeastern fringes of the North Asian Craton)     

I. V. Buchko  A. A. Sorokin  V. A. Ponomarchuk  A. V. Travin  A. P. Sorokin  Ir. V. Buchko 《Doklady Earth Sciences》2010,435(2):1560-1563

This article discusses the results of ⁴⁰Ar/³⁹Ar geochronological studies on the age of the gold-silver mineralization of the Dess occurrence hosted by the granitoids of the Tynda-Bakaran rock complex, which is 129–128 Ma. This estimate coincides with the time of the formation of the Mo mineralization (125–122 Ma) hosted by the rocks of the same rock complex. This allows dating the Au-Ag and Mo mineralizations from the same ore formation period that manifests itself in the granitoids of the North Stanovoi metallogenic belt that were formed in the environment of a transform continental margin. There exists the following sequence of changes in the mineral occurrences from the south to the north: Au-Ag-Au-Mo(Au).  相似文献   

The Triassic stage of mafic magmatism in the Dzhugdzhur–Stanovoi superterrane (southern framing of the North Asian craton)     

I.V. Buchko  A.A. Sorokin  E.B. Sal'nikova  A.B. Kotov  S.D. Velikoslavinskii  A.M. Larin  A.E. Izokh  S.Z. Yakovleva 《Russian Geology and Geophysics》2010,51(11):1157-1166

With U-Pb zircon dating, the ages of the Ul'degit (228 ± 1 Ma) and Chek-Chikan (203 ± 1 Ma) mafic massifs were determined. These massifs were earlier considered to form at the Early Precambrian stage of the geologic evolution of the Dzhugdzhur–Stanovoi superterrane. In geochemical features the igneous rocks of the massifs show relation with a within-plate source, on the one hand, and are similar to igneous rocks of subduction zones, on the other. They might have formed after subduction, which caused the intrusion of gabbroids of the Lucha massif (248 ± 1 Ma) and diorites of the Tok-Algoma complex (238 ± 2 Ma), followed by the fracturing of the subducted plate.  相似文献   

The age and tectonic setting of the Lukinda dunite-gabbro-anorthosite massif in the east of the Selenga-Stanovoi superterrane,Central Asian Fold Belt     

I.V. Buchko  A.A. Sorokin  A.B. Kotov  A.V. Samsonov  Yu.O. Larionova  V.A. Ponomarchuk  A.M. Larin 《Russian Geology and Geophysics》2018,59(7):709-717

Results of integrated ⁴⁰Ar/³⁹Ar, Rb-Sr, and Sm-Nd geochronological studies of the Lukinda dunite-troctolite-gabbro-anorthosite massif in the northeast of the Selenga-Stanovoi superterrane, Central Asian Fold Belt, are presented. It is shown that this massif is much younger than formerly thought: 249 ± 14 to 251 ± 15 Ma vs. Paleoproterozoic. This date of magmatism corresponds to one of the stages of the formation of the Selenga-Vitim belt, which ranks among the largest Phanerozoic volcanoplutonic belts in Central Asia.  相似文献   

First data on noble metal minerals in the metamafic rocks of the Ilikan lithotectonic zone, southeastern framing of the North-Asian craton     

I. V. Buchko  A. A. Sorokin  V. I. Rozhdestvina  Ir. V. Buchko 《Geochemistry International》2013,51(12):1025-1030

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Fragments of the oceanic crust in the junction zone between the Zverevskii and Stanovoi complexes in the southeastern margin of the North Asian Craton     

I. V. Buchko  A. A. Sorokin 《Doklady Earth Sciences》2014,455(1):270-273

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Geochemical features and geodynamic setting of formation of the Lukinda dunite–troctolite–gabbro massif (southeastern framing of the Siberian Platform)     

I.V. Buchko  A.A. Sorokin  V.A. Ponomarchuk  A.E. Izokh 《Russian Geology and Geophysics》2012,53(7):636-648

The Lukinda dunite–troctolite–gabbro massif in the Selenga–Stanovoy superterrane on the southeastern framing of the Siberian Platform was earlier considered Precambrian. The performed ⁴⁰Ar/³⁹Ar dating of the massif plagioclase yielded an Early Permian age (285 ± 7.5 Ma). The main specific petrochemical features of the intrusion rocks during their crystallization differentiation are an increase in SiO₂ and CaO contents and a decrease in FeO_tot content, with TiO₂ content remaining low and showing minor variations. A specific geochemical feature of the Lukinda massif ultrabasite–basites is a slight domination of LREE over HREE, with (La/Yb)_N= 1.0–8.2. The depletion of the massif rocks in LILE (except for Sr and Ba), REE, and HFSE suggests that the massif formed on an active continental margin.  相似文献