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Geological framework of Dzhida-Khamar-Daban zone. 1. Cenozoic deposits of Tunka rift basin. 2. Cenozoic basalts. 3. Mesozoic volcanosedimentary rocks. 4. Late Paleozoic (298 Ma) granosyenite and syenite. 5. Ordovician (478-495 Ma) granitoids. 6. Ordovician diorite and gabbro. 7. Cambrian (505-540 Ma) tonalite and granodiorite. 8. Cambrian gabbro and diorite. 9. Vendian-Early Paleozoic sedimentary and volcanosedimentary rocks of back-arc basin. 10. Vendian-Early Paleozoic volcanic and volcanosedimentary rocks of island arc. 11. Ultramafic rocks (fragments of dismembered ophiolites). 12. Vendian-Early Paleozoic carbonate cover of Tuva-Mongolia microcontinent. 13. Gargan block (Early Precambrian). 14. Siberian craton. 15. Thrusts. 16. Normal faults. 17. Faults of uncertain geometry. 18. Grade contour lines of Ordovician metamorphism: garnet (I), staurolite and andalusite (II), sillimanite (III), sillimanite-K-feldspar (IV), hypersthene (V). 19. Grade contour lines of Cambrian metamorphism: garnet (I), staurolite and disthene (II), sill imanite (III). 20. Previously hypothesized boundary between Dzhida (in the south) and Khamar-Daban (in the north) zones.
Contexts in source publication
Context 1
... arc rocks in the Dzhida zone ( Fig. 2) are boninite- basalt, rhyolite-andesite, and tuff, as well as mafic-ultramafic and plagiogranite-diorite assemblages, of which the mafic-ul- tramafic one (dismembered ophiolite) presumably composes the base of an island arc ( Gordienko et al., 2007). The typically island arc plagiogranite-diorite assemblage was dated at 504-506 Ma ( ...
Context 2
... the Khamar-Daban zone (Khamar-Daban Group), the difference being only in a higher metamorphic grade of the Khamar-Daban rocks and a younger age of the uppermost Dzhida section where shallow marine sediments appear. Thus, the Khamar-Daban zone and the northern Dzhida zone may belong to a single back-arc basin associated with the Dzhida island arc (Fig. ...
Context 3
... al., 2007), which corre- sponds to the age of metamorphism in the Khamar-Daban zone. The pattern of metamorphic zones is worth of special note. Granulite metamorphism is restricted to a narrow part of the Khamar-Daban zone immediately along the craton border, while other rocks are in amphibolite facies. Isogrades crosscut stratigraphic boundaries (Fig. 2). The grade of rocks over a greater part of the Dzhida zone is no higher than greenschist facies and reaches amphibolite facies only around island arc plagiogranite and granodiorite intrusions. Amphibo- lite metamorphism in the Dzhida zone associated with em- placement of island arc granitoids is obviously older than amphibolite and ...
Context 4
... no higher than greenschist facies and reaches amphibolite facies only around island arc plagiogranite and granodiorite intrusions. Amphibo- lite metamorphism in the Dzhida zone associated with em- placement of island arc granitoids is obviously older than amphibolite and granulite facies in the Khamar-Daban zone related to collisional plutonism (Fig. ...
Citations
... However, the recent studies made it possible to extract the faunally characterized Devonian-Carboniferous sediments from the Oldynda Formation, as well as to revise the age of the Istashi, Khimgilda formations and Surkhrebt Sequence and ascribe them to the Upper Devonian, and Middle-Upper Carboniferous, respectively (Gordienko et al., 2010;Ruzhenstev et al., 2012;Minina et al., 2016;Gosudarstvennaya ..., 2016). In different tectonic schemes, the Uda-Vitim zone is considered as the Eravna island-arc terrane (Bulgatov and Gordienko, 2004;Zorin et al., 2009), Uda-Vitim Caledonide zone (Belichenko, 1962(Belichenko, , 1977, Uda-Vitim island-arc system (Gordienko et al., 2010), Eravna trough of the Dzhida-Vitim system of synclinoriums and volcanotectonic structures (Geologicheskaya …, 2016). We believe that the Uda-Vitim zone belongs to the Baikal-Vitim orogenic system of the Western Transbaikalia (Ruzhentsev et al., 2012). ...
... The Baikal-Vitim Fold System is located to the south of the Baikal-Muya Belt. These structural units are separated by the Baikal Metamor phic Belt, which plays the role of a collisional front [41], or the Barguzin Metamorphic Block [16]. The Baikal-Vitim (Uda-Vitim) Fold System is the late Neoproterozoic-Cambrian suprasubduction belt that arose on the early-middle Neoproterozoic heteroge neous basement [11-13, 33, 40, 41]. ...
... When the thick ness of the lithospheric block that has wedged subduc tion zone is sufficient, the process can cease with uplift and erosion of the territory. (12)(13)(14)(15)(16)(17) legend to graphs: (12) orthoamphibolite SB0712A, (13) gneiss SB0712V, (14) plagiogranite dike SB0712D, (15,16) leucogranite and tonalite SB072P16 and SB072P17, respectively; (17) leucogranite dike SB098B (location of sample is shown in Fig. 2c). Average values for enderbite gneiss for the studied area, high Al enderbite gneiss SB094B from Pisany Kamen Cape, and high silicic adakite (HSA), after [86], are shown. ...
... When the thick ness of the lithospheric block that has wedged subduc tion zone is sufficient, the process can cease with uplift and erosion of the territory. (12)(13)(14)(15)(16)(17) legend to graphs: (12) orthoamphibolite SB0712A, (13) gneiss SB0712V, (14) plagiogranite dike SB0712D, (15,16) leucogranite and tonalite SB072P16 and SB072P17, respectively; (17) leucogranite dike SB098B (location of sample is shown in Fig. 2c). Average values for enderbite gneiss for the studied area, high Al enderbite gneiss SB094B from Pisany Kamen Cape, and high silicic adakite (HSA), after [86], are shown. ...
The paper presents new geological, geochemical, and isotopic data on igneous rocks from a thor�
oughly studied area in the western Baikal–Muya Belt, which is a representative segment of the Neoprotero�
zoic framework of the Siberian Craton. Three rock associations are distinguished in the studied area: granu�
lite–enderbite–charnockite and ultramafic–mafic complexes followed by the latest tonalite–plagiogranite–
granite series corresponding to adakite in geochemical characteristics. Tonalites and granites intrude the
metamorphic and gabbroic rocks of the Tonky Mys Point, as well as Slyudyanka and Kurlinka intrusions. The
tonalites yielded a U–Pb zircon age of 595 ± 5 Ma. The geochronological and geological information indi�
cate that no later than a few tens of Ma after granulite formation they were transferred to the upper lithosphere
level. The Sm–Nd isotopic data show that juvenile material occurs in rocks of granitoid series (εNd(t) = 3.2–7.1).
Ophiolites, island�arc series, eclogites, and molasse sequences have been reviewed as indicators of Neoprot�
erozoic geodynamic settings that existed in the Baikal–Muya Belt. The implications of spatially associated
granulites and ultramafic–mafic intrusions, as well as granitoids with adakitic geochemical characteristics for
paleogeodynamic reconstructions of the western Baikal–Muya Belt, are discussed together with other struc�
tural elements of the Central Asian Belt adjoining the Siberian Platform in the south.
Research subject . Fluid inclusions in quartz of three vein systems associated with tectonic cracks occurred during the development of thrust and shear deformations of the Western Transbaikalia. Vein systems localized in volcanic, terrigenous and granite rocks. Methods . The composition of fluid inclusions was studied by microthermometry, Raman spectroscopy and gas chromatography-mass spectrometry. Results . The quartz under study was formed by high-density medium-temperature NaCl-KCl and a low- and medium-salinity water-carbon dioxide fluid (2-5 wt % NaCl eq.). A distinctive feature of quartz of different vein systems was found to be the gas phase composition of inclusions associated with the composition of host rocks. The minimum temperatures of vein quartz formation were determined to range from 180 to 450°C under the minimum fluid pressure values of 0.7-2.9 kbar. Conclusions . Complex vein systems of the junction zone of the Baikal-Muiskaya and Barguzino-Vitimskay SFZ, confined to different host rocks and having different structural positions, are characterized by a similar fluid composition and a common thermodynamic history reflecting the change of deformation aggregates. The metamorphogenic-hydrothermal nature of the fluid involved in the formation of quartz vein systems was established. The development of the hydrothermal system was accompanied by its influence on the host rocks, which was manifested in the variations of fluid composition. The evolution of a single hydrothermal system is associated with tectonic deformation processes, which can be described by three dynamic stages corresponding to three quartz generations.
High magnesium metavolcanites, which are found for the first time in the Tunka terrane (the Baikal-Khubsogul region), are described. By the content of MgO (12-16%), SiO2 (up to 52%), and alkali oxides, they are classified as metamorphosed picrites. There are two groups of them, divided by the TiO2 content and by the TiO2/Al2O3 ratio. When making a distinction between geochemical peculiarities of two groups, their rare-element composition is intermediate between picrites and boninites. The comparison between metavulcanites and their nonmetamorphosed analogues is made, some aspects of their genesis are considered, and the conclusion is made that these metavulcanites mark paleospreading of the back-arc basin.
