Age and Provenance Areas of Terrigenous Rocks of the Dzhida Terrane: Results of U—Th—Pb (LA-ICP-MS) Geochronological Study of Detrital Zircons     

L. Z. Reznitskii  V. P. Kovach  I. G. Barash  Yu. V. Plotkina  K. -L. Wang  H. -Y. Chiu 《Stratigraphy and Geological Correlation》2018,26(5):489-513

The results of U—Th—Pb (LA-ICP-MS) geochronological studies of detrital zircons from terrigenous rocks of the Dzhida terrane of the Central Asian Fold Belt (CAFB) are presented. The data obtained allow us to distinguish the following age maxima (Ma): 578 and 634 (Vendian); 720, 823, and 919 (Late Riphean); 1922, 2090, 2225, and 2321 (Early Proterozoic). A number of zircons have Late Archean age in the interval of 2670–2980 Ma. Taking into account Late Cambrian age (504–506 Ma) of intrusive rocks that intruded the Dzhida terrane, a possible sedimentation period of sequences of this terrane is estimated to be in the interval of 580–510 Ma (from Vendian to Late Cambrian). The possible provenance areas of terrigenous sediments are proposed and the previously proposed models of geodynamic evolution of the Dzhida terrane are correlated with new geochronological data.  相似文献   

Crystal chemistry of some Mg,Cr, V normal spinels from Sludyanka (Lake Baikal,Russia): the influence of V<Superscript>3+</Superscript> on structural stability     

B.?LavinaEmail author  L.Z.?Reznitskii  F.?Bosi 《Physics and Chemistry of Minerals》2003,30(10):599-605

A suite of vanadian magnesiochromites from the Sludyanka metamorphic complex (South Lake Baikal, Russia) were investigated by means of X-ray single-crystal structural refinements and microprobe analyses. Various morphological types of Cr–V-bearing Mg spinels are located in calc–silicate metamorphic rocks, in an assemblage that also contains other Cr–V minerals such as escolaite–karelianite, uvarovite–goldmanite, Cr–V-bearing clinopyroxene, tourmaline, amphibole, mica, etc. Along the suite there is widespread V–Cr substitution (0.14 V³⁺ 0.95 afu, 1.02 Cr³⁺ 1.80 afu), and minor, variable Al contents. The Mg content of slightly lesser than 1 afu, is almost constant. Cell parameters and octahedral bond distances increase with V³⁺. Unexpectedly, the Mg–O tetrahedral bond distance also increases slowly with V³⁺. This weak dragging effect contributes towards maintaining distortion of the oxygen array with respect to the ideal CCP, thus providing a shielding effect, which reduces V³⁺–V³⁺ repulsion. This leads to the energetic stabilization of the structure, in spite of the increase of bond strain with increasing V³⁺ contents.  相似文献   

Age and origin of the Kitoi sillimanite schist deposit,eastern Siberia     

Levitskii  V. I.  Reznitskii  L. Z.  Sal’nikova  E. B.  Levitskii  I. V.  Kotov  A. B.  Barash  I. G.  Yakovleva  S. Z.  Anisimova  I. V.  Plotkina  Yu. V. 《Doklady Earth Sciences》2010,431(1):394-398

Doklady Earth Sciences -  相似文献   

High-magnesium picrite–basalt associations of the Tunka terrane (Baikal–Hövsgöl region) as an indicator of the back-arc basin spreading     

S.I. Shkol'nik  V.G. Belichenko  L.Z. Reznitskii 《Russian Geology and Geophysics》2013,54(2):153-165

High-Mg metabasalts and metapicrites discovered within the Urtagol Formation in the central zone of the Tunka bald mountains (East Sayan) are studied. In geochemistry the high-Mg metavolcanics are similar to subductional rocks. We have established that the Nb-rich recycled material of oceanic crust (RSC) was a source of elements for high-Ti metabasalts, and subductional fluid rich in LREE and Th relative to Nb was the source of these elements for high-Ti metapicrites. The enrichment of low-Ti metavolcanics, formed, probably, at the early stages of the basin opening, was due to the contamination of melt with continental-crust material. A comparison of the metavolcanics with nonmetamorphosed analogs is made, and some genesis aspects are considered. The results obtained led to the conclusion that the metavolcanics mark the paleospreading of the back-arc basin.  相似文献   

New data about structure and time of formation of the Khamar-Daban terrane: U-Pb LA-ICP-MS zircon ages     

S. I. Shkol’nik  A. M. Stanevich  L. Z. Reznitskii  V. B. Savelieva 《Stratigraphy and Geological Correlation》2016,24(1):19-38

This paper provides new data on the age of detrital zircons from metaterrigenous rocks of the Khamardaban Group (Kornilovskaya and Shubutuiskaya formations) which crown the succession of the Khamar-Daban terrain. It was established that the accumulation of the protoliths of both formations occurred in the interval between the Late Riphean and Early Ordovician. In this case, there is a difference between sequences of Shubutuiskaya and Kornilovskaya formations due to a sharp change in a provenance area and depositional conditions, which is a consequence of the change in the paleogeodynamic environment. In addition, this indicates the tectonic juxtaposition of these sequences and probability of accumulation of deposits of the Shubutuiskaya Formation within Dzhida island arc system.  相似文献   

Nd isotope systematics of the Vendian–Early Cambrian sedimentary ores in the northern segment of the Paleoasian Ocean     

E. F. Letnikova  F. A. Letnikov  S. I. Shkol’nik  T. Yu. Cherkashina  L. Z. Reznitskii  I. A. Vishnevskaya 《Doklady Earth Sciences》2016,466(1):42-46

Isotope–geochemical studies of Mn, P, and Ba ores were performed in order to establish the influence of submarine hydrotherms on the formation of Early Cambrian sedimentary rocks of the southern environs of the Siberian Platform. Based on study of the geochemical and isotope (ε_Nd) characteristics of the shallow-water Mn and Ba ores and phosphorites of southern environs of the Siberian Platform with similar ages, two types of sedimentary basins of the different geodynamic origins were distinguished: intraplate oceanic and those of the active continental margin, for which the sources of ore materials differ by the proportions of the mantle and contaminated crustal matter.  相似文献   

Collisional granitoids of the Dzhida zone of the Central Asian Fold belt,Southwestern Transbaikalia: Age and conditions of the formation     

I. V. Gordienko  V. P. Kovach  A. L. Elbaev  A. B. Kotov  E. B. Sal’nikova  L. Z. Reznitskii  S. Z. Yakovleva  I. V. Anisimova 《Petrology》2012,20(1):40-58

This paper considers the geological structure, composition, and age of the Darkhintui, Barun-Gol, and Khuldat granitoid plutons of the Dzhida zone of Caledonides of the Central Asian Fold belts. These plutons were formed in the Late Cambrian-Early Ordovician in the range between 490 ± 2 and 477 ± 6 Ma, after tectonic juxtaposition of the oceanic and island-arc complexes of the Dzhida Zone and volcanogenic-carbonate-terrigenous rocks of the Khamardaban zone, i.e., at the collisional stage of the region evolution. Geological, geochronological, geochemical, and Nd isotope data indicate that the collisional granitoids of the Dzhida zone were derived by melting of continental crust thickened through accretion. The sources for parental melts of the granitoids were presumably Vendian-Early Cambrian juvenile igneous rocks of ophiolite and island-arc complexes, as well as the crustal material of the Lower Paleozoic flyschoid sediments of the back-arc basin of the Dzhida zone and metaterrigenous rocks of the Khamardaban zone.  相似文献   

Late Permian and Early Triassic magmatic pulses in the Angara–Taseeva syncline,Southern Siberian Traps and their possible influence on the environment     

M.T. Paton  A.V. Ivanov  M.L. Fiorentini  N.J. McNaughton  I. Mudrovska  L.Z. Reznitskii  E.I. Demonterova 《Russian Geology and Geophysics》2010,51(9):1012-1020

Recently it has been suggested that the major influence on the environment from Siberian Traps magmatism was due to the interaction of magma and organic-rich shale and petroleum-bearing evaporites, with the subsequent creation and outburst of toxic gases (Siberian gas venting: SGV model). In part this idea was supported by a U-Pb age of 252.0 ± 0.4 Ma for one of the dolerite sills in the southeastern Siberian Traps: the age corresponds to the Permo-Triassic boundary and its known mass extinctions of biota. In this study two other dolerite sills were dated using zircons by the U-Pb SHRIMP method at 254.2 ± 2.3 Ma and 249.6 ± 1.5 Ma. The former age is in agreement within error with the age previously published for the dolerite sills, whereas the latter age is in agreement with U-Pb ages published for lava and intrusions from the northern Siberian Traps. The new ages corresponds to the Cahngshingian/Wuchiapingian or Permian/Triassic and Spathian/Smithian boundaries, respectively. Review of ⁴⁰Ar/³⁹Ar and U-Pb SHRIMP ages previously published for the southeastern Siberian Traps shows that three other pulses of magmatism probably took place at respectively Anisian/Spathian, Late/Middle Anisian and Landian/Anisian boundaries. Thus it is possible that the SVG model can be applied also to lesser biotic extinctions and recoveries in proximity and aftermath to the main Permo-Triassic extinction.  相似文献   

Genesis of manganese ores and their position in sedimentary basins of the eastern segment of the Paleoasian Ocean: Sm-Nd isotopic and geochemical evidence     

E. F. Letnikova  F. A. Letnikov  A. B. Kuznetsov  S. I. Shkol’nik  L. Z. Reznitskii  T. L. Turchenko 《Doklady Earth Sciences》2011,439(2):1157-1162

The first geochemical and Sm-Nd isotopic characteristics of Neoproterozoic-Cambrian manganese ores from the south folded framing of the Siberian Craton have been obtained. For manganese ores from the Podikat deposit, Tsagan-Zaba and, in part, for Slyudyanka ore manifestations, an explicit positive Eu anomaly and variable Ce behavior are typical no depending on degree of metamorphism. In the rocks of Itantsa ore manifestation and, in part, in those of Slyudyanka, REEs have distribution patterns similar to the normal sedimentary pattern and are characterized by a gentle slope with a negative Eu anomaly and by the absence of a Ce anomaly. With the geochemical peculiarities, including REE distribution in them, on aggregate, reconstruction of vast hydrothermal fields within the south framing of the Siberian Craton and spatial position of the studied manganese basins relative to the craton has become possible.  相似文献   

Stages of Tectono-Magmatic Activity in the Border Zone of the Siberian Platform and the Tannuola–Khamsara Segment of the CAFB (According to the Results of U–Pb Isotope Studies)     

Shkolnik  S. I.  Letnikova  E. F.  Reznitskii  L. Z.  Ivanov  A. V.  Proshenkin  A. I. 《Doklady Earth Sciences》2021,498(2):451-455

Doklady Earth Sciences - Based on the dating of metamorphic and igneous rocks of the northeastern part of the Khamsara terrane, the main stages of tectono-magmatic activity at the border of two...  相似文献