Age of the Ust’-Gilyui sequence in the Stanovoi Complex of the Selenga-Stanovoi Superterrain, Central Asian fold belt     

S. D. Velikoslavinskii  A. B. Kotov  E. B. Salnikova  A. M. Larin  A. A. Sorokin  A. P. Sorokin  V. P. Kovach  E. V. Tolmacheva  S. Z. Yakovleva  I. V. Anisimova 《Doklady Earth Sciences》2012,444(2):661-665

According to the results of U-Pb geochronological investigations, the age of the amphibolite protoliths (metabasalts) in the Ust??-Gilyui sequence within the Stanovoi Complex of the Amazar-Gilyui structural and formational zone in the Selenga-Stanovoi Superterrain of the Central Asian fold belt can be estimated at 193 ± 1 Ma. The Nd model age of the Ust??-Gilyui metasedimentary rocks is in the interval of t _Nd(DM) = 1.1?C3.1 Ga. This information along with the previously obtained geochronological data are indicative of the fact that the Ust??-Gilyui sequence consists of metasedimentary and metavolcanic rocks of various ages: (1) volcanic rocks with the age of 193 ± 1 Ma; (2) metasedimentary and metavolcanic rocks broken through by the Paleozoic granitoids dated to 370 Ma and characterized by minimum estimations of t _Nd(DM) = 1.1 Ga, i.e., rocks with an age of 1.1?C0.4 Ga. In addition, it is quite possible that this sequence also includes more ancient rocks. The SSS Amazar-Gilyui structural and formational zone is likely to be a tectonic mélange composed of the metasedimentary and metavolcanic rocks of the Mesozoic and, probably, Paleozoic and Early Precambrian ages. The studied zone was formed in the Mesozoic, most likely, in the course of the collision processes initiated by the closing up of the Mongol-Okhotsk Ocean.  相似文献   

Age of the Vishnyakovskoe deposit of rare-metal pegmatites (East Sayan): U-Pb geochronological study of manganotantalite     

E. B. Sal’nikova  A. M. Larin  S. Z. Yakovleva  A. B. Kotov  V. A. Glebovitskii  A. V. Tkachev  I. V. Anisimova  Yu. V. Plotkina  B. M. Gorokhovskii 《Doklady Earth Sciences》2011,441(1):1479-1483

The U-Pb age of the manganotantalite from rare-metal pegmatites of the Vishnyakovskoe deposit (East Sayan Belt) has been assessed at 1838 ± 3 Ma. The acquired data indicate the pegmatites of this deposit and associated granites of the Sayan complex belong to the postcollision South Siberian igneous belt (1.88–1.84 Ga), which stretches along the southwestern frame of the Siberian Craton by more than 2500 km, from the Yenisei Ridge to the Aldan Shield. Formation of this igneous belt is related to joining (starting from about 1.9 Ga BP) of the series of continental microplates and island arcs to the Siberian Craton; this led to final stabilization of the craton at about 1.8 Ga BP.  相似文献   

Gold and silver tellurides in the Shirokinsky ore-and-placer cluster,the Sette-Daban Ridge,Yakutia     

G. S. Anisimova  L. A. Kondrat’eva  N. V. Leskova 《Geology of Ore Deposits》2011,53(7):620-625

The first findings of Au and Ag tellurides (sylvanite and petzite) in sulfide-quartz ore of the Shirokinsky ore and placer cluster located in the Sette-Daban Horst-Anticlinorium are described. These minerals were found for the first time at the gold deposits of East Yakutia. The chemical compositions (wt %) of sylvanite (23.65–24.61 Au, 12.7–13.13 Ag, 59.3–59.97 Te, 96.26–97.97 in total) and petzite (23.17–25.24 Au, 42.27–44.40 Ag, 31.26–33.37 Te, 98.19–102.55 in total) are reported. Galena as a host mineral is associated with native gold, electrum, hessite, and stützite. The finding of Au-Ag and Ag tellurides provides evidence for the development of Au-telluride mineralization in the Sette-Daban Horst-Anticlinorium.  相似文献   

Late Riphean age of conglomerates from the Kholbonur complex of Songino block, Central Asian Caledonides     

I. K. Kozakov  E. B. Salnikova  V. P. Kovach  I. V. Anisimova  A. M. Fedoseenko  S. Z. Yakovleva 《Stratigraphy and Geological Correlation》2013,21(5):482-495

The Early Caledonian folded area of Central Asia comprises a variety of continental crust fragments with Early to Late Precambrian crystalline basement. Crystalline rocks, which form part of the Songino block, outcrop at the junction between the Dzabkhan and Tuva-Mongolian terranes. The Bayannur zone in the southern part of the Songino block contains the Bayannur migmatite-gneiss and Kholbonur terrigenous-metavolcanic metamorphic complexes. Previous studies provide the 802 ± 6 Ma age for the regional metamorphism and folding within the Bayannur complex. On the basis of the minimum Nd model age of 1.5 Ga, gneisses from this complex cannot be regarded as Early Precambrian. Two main rock associations were distinguished in the Kholbonur complex. Mafic metavolcanics compose the dominant lithology of the first rock association, whereas the second association comprises terrigenous-volcanic and predominantly terrigenous suites. The rocks of the predominantly terrigenous suite, including mudstones, sandstones, and conglomerates, are interpreted to derive from the Late Riphean accretionary prism. The lithology and composition of metaterrigenous rocks suggest that they were possibly derived from erosion of a volcanic arc. The upper age limit of this suite is constrained by postkinematic granites (790 ± 3 Ma; U-Pb zircon), the lower age is given by plagiogranite (874 ± 3 Ma; U-Pb zircon) from comglomerate pebbles. Therefore, the timing of deposition of this terrigenous suite can be bracketed by the 874–790 Ma time interval. These ages and compositional features of the Kholbonur complex terrigenous rocks suggest that the convergence took place at around 870–880 Ma and thus it can be correlated with the divergent processes between the blocks of continental crust composing the supercontinent Rodinia.  相似文献   

Age and tectonic position of the Ulkan Group, the stratotype of the Upper Karelian in Eastern Siberia and the Far East     

A. M. Larin  A. B. Kotov  E. B. Sal’nikova  V. A. Glebovitskii  S. D. Velikoslavinskii  S. Z. Yakovleva  I. V. Anisimova 《Doklady Earth Sciences》2013,449(2):375-379

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Vendian stage in formation of the Early Caledonian superterrane in Central Asia     

I. K. Kozakov  E. B. Sal’nikova  V. P. Kovach  V. V. Yarmolyuk  I. V. Anisimova  A. M. Kozlovskii  Yu. V. Plotkina  T. A. Myskova  A. M. Fedoseenko  S. Z. Yakovleva  A. M. Sugorakova 《Stratigraphy and Geological Correlation》2008,16(4):360-382

Granitoids and metamorphic rocks of the Baidarik basement block of the Dzabkhan microcontinent are studied in terms of geology, geochronology (U-Pb dating of zircon microfractions and individual grains) and Nd isotopic-geochemical systematics. As is established, the formation history of metamorphic belt (disthene-sillimanite facies) in junction zone of the Baidarik block and Bayankhongor zone of the Late Riphean (～665 Ma) ophiolite association characterizes development of the Vendian (～560–570 Ma) active continental margin. The high-P metamorphic rocks of that time span evidence formation of structures with the Earth’s crust of considerable thickness. In Central Asia, events of the Vendian low-gradient metamorphism are established also in the Tuva-Mongolian massif, Kan block of the East Sayan Mountains, and South Chuya inlier of the Caledonides in the Altai Mountains. Based on these data, it is possible to distinguish the Late Baikalian stage in development of the Early Caledonian superterrane of Central Asia, which antedated the subsequent evolution of this structure during the Late Cambrian-Ordovician. The high-gradient metamorphism that affected most intensively the southeastern part of the Baidarik block can be correlated with the Early Paleozoic (525–540 Ma) evolution of active continental margin and associated development of the Vendian oceanic basins and island arcs of the Ozernaya zone.  相似文献   

Early cambrian ophiolites of the boshchekul zone (Central Kazakhstan): Structure of sections and age substantiation     

K. E. Degtyarev  A. V. Ryazantsev  A. B. Kotov  E. B. Sal’nikova  I. V. Anisimova  S. Z. Yakovleva 《Doklady Earth Sciences》2010,431(2):413-417

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Rare-metal granitoids of the Ulug-Tanzek deposit (Eastern Tyva): Age and tectonic setting     

Yarmolyuk  V. V.  Nikiforov  A. V.  Sal’nikova  E. B.  Travin  A. V.  Kozlovskiy  A. M.  Kotov  A. B.  Shuriga  T. N.  Lykhin  D. A.  Lebedev  V. I.  Anisimova  I. V.  Plotkina  Yu. V.  Yakovleva  S. Z. 《Doklady Earth Sciences》2010,430(1):95-100

Doklady Earth Sciences -  相似文献   

Early Cretaceous age of regional metamorphism of the Stanovoi group in the Dzhugdzhur-Stanovoi foldbelt: Geodynamic implications     

A. M. Larin  E. B. Sal&#;nikova  A. B. Kotov  V. A. Glebovitsky  S. D. Velikoslavinsky  A. A. Sorokin  S. Z. Yakovleva  A. M. Fedoseenko  I. V. Anisimova 《Doklady Earth Sciences》2006,409(5):727-731

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Protoliths of the metamorphic rocks of the Fedorov Complex, Aldan shield: Character, age, and geodynamic environments of origin     

S. D. Velikoslavinsky  A. B. Kotov  E. B. Sal’nikova  V. P. Kovach  V. A. Glebovitsky  N. Yu. Zagornaya  S. Z. Yakovleva  E. V. Tolmacheva  I. V. Anisimova  A. M. Fedoseenko 《Petrology》2006,14(1):21-38

Geochemical data indicate that the protoliths of the overwhelming majority of the metamorphic rocks composing the Fedorov Complex in the Aldan granulite megacomplex were volcanic rocks of three groups, which occur in different proportions in the complex: (i) volumetrically predominant (no less than 90%) continuous differentiated island-arc basalt-andesite-dacite-rhyolite series, (ii) within-plate basalts, whose composition was similar to that of low-Ti traps, and (iii) basalts of composition similar to that of continentalrift basalts. The U-Pb zircon crystallization age of the metamorphosed basaltic andesites of the Fedorov Complex was estimated at 2006 ± 3 Ma, which testifies, when considered together with preexisting geochronological data, that the complex was produced during a time span of no longer than 25 m.y. A model is proposed according to which the complex was produced within the geodynamic system of the active continental margin of the Olekma-Aldan continental microplate and the Fedorov island arc.  相似文献