Neoproterozoic complexes of the shelf cover of the Dzabkhan terrane basement in the Central Asian Orogenic Belt

The formation stages of high-grade metamorphic complexes and the related granitoids of the Dzabkhan terrane basement are considered. The age data (U–Pb method, TIMS) of zircons from the trondhjemite block of the eastern part of the Dzabkhan terrane, which is directly overlain by the dolomite sequenc...

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Bibliographic Details
Published in:Stratigraphy and geological correlation 2017-09, Vol.25 (5), p.479-491
Main Authors: Kozakov, I. K., Kuznetsov, A. B., Erdenegargal, Ch, Salnikova, E. B., Anisimova, I. V., Plotkina, Ju. V., Fedoseenko, A. M.
Format: Article
Language:English
Subjects:
Archaeology
Cambrian
Carbonates
Continental crust
Dolomite
Dolostone
Earth and Environmental Science
Earth Sciences
Fragments
Geochemistry
Geochronology
Geochronometry
Geological time
Geophysics/Geodesy
Historical Geology
Island arcs
Isotopes
Lead
Magma
Metamorphic rocks
Precambrian
Radiometric dating
Seawater
Sedimentology
Sequencing
Strontium isotopes
Structural Geology
Yields
Zircon
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Summary:The formation stages of high-grade metamorphic complexes and the related granitoids of the Dzabkhan terrane basement are considered. The age data (U–Pb method, TIMS) of zircons from the trondhjemite block of the eastern part of the Dzabkhan terrane, which is directly overlain by the dolomite sequence of the Tsagaan Oloom Formation, are given. Trondhjemites yield the U–Pb zircon age of 862 ± 3 Ma. In their structural position, they are assigned to typical postmetamorphic formations that determine the formation and cratonization of rocks of the host block. The geochronological study of trondhjemites gives grounds to distinguish fragments of the continental crust in the Dzabkhan terrane basement, the formation of which occurred at different periods of time: ∼860 and ∼790 Ma. Geological–geochronological and Sm‒Nd isotope–geochemical studies indicate that the Dzabkhan terrane basement is not a single block of the Early Precambrian continental crust, but a composite terrane, comprising Neoproterozoic ensialic and island-arc structural and compositional complexes. Correlation of Sr isotopic characteristics with the 87 Sr/ 86 Sr variation curve in the Neoproterozoic and Cambrian seawater shows that carbonate deposits accumulated at the eastern margin of the Dzabkhan terrane near the end of the Neoproterozoic, 700–550 Ma, and in the central part of the terrane in the Early Cambrian, 540–530 Ma.
ISSN:0869-5938
1555-6263
DOI:10.1134/S0869593817050045