Geochronology and Geodynamic Settings of Metamorphic Complexes in the Southwestern Part of the Tuva-Mongolian Terrane, Central Asian Foldbelt

The Sangilen and Khan-Khuhei blocks in the southwestern part of the Tuva-Mongolian terrane (TMT) combine into a composite structure, formed in the course of the Early Paleozoic (ca. 505–495 Ma) regional low- to moderate-pressure metamorphism. Manifestations of an earlier higher pressure metamorphism...

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Bibliographic Details
Published in:Stratigraphy and geological correlation 2021-07, Vol.29 (4), p.389-410
Main Authors: Kozakov, I. K., Kovach, V. P., Salnikova, E. B., Kröner, A., Adamskaya, E. V., Azimov, P. Ya, Gorokhovsky, B. M., Ivanova, A. A., Oydup, Ch. K., Plotkina, Yu. V.
Format: Article
Language:English
Subjects:
Archaeology
Carbonates
Composite structures
Earth and Environmental Science
Earth Sciences
Geochronology
Geochronometry
Geophysics/Geodesy
High temperature
Historical Geology
Isotopes
Metamorphic rocks
Metamorphism
Paleozoic
Passive margins
Platforms (geology)
Pressure
Sedimentology
Structural Geology
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Summary:The Sangilen and Khan-Khuhei blocks in the southwestern part of the Tuva-Mongolian terrane (TMT) combine into a composite structure, formed in the course of the Early Paleozoic (ca. 505–495 Ma) regional low- to moderate-pressure metamorphism. Manifestations of an earlier higher pressure metamorphism are known in both blocks. The upper age limit for the Sangilen block is defined by granites with an age of 536 ± 6 Ma. The early metamorphic rocks in both blocks are intruded by the granitoids of the Orto-Adyr complex with ages of 516 ± 5 and 513 ± 4 Ma, respectively. The emplacement of this complex preceded the Early Paleozoic (505–495 Ma) low- to moderate-pressure metamorphism. The high-temperature metamorphic rocks of the Sangilen and Khan-Khuhei blocks of TMT can be considered as the fragments of the Late Ediacaran higher pressure metamorphic belt, accreted to the TMT margin at ca. 510–505 Ma and reworked in the interval of 505–495 Ma under conditions of a regional low- to moderate-pressure metamorphism. The emplacement of the granitoids of the Orto-Adyr complex marks the conversion of the passive margin of the Neoproterozoic TMT block, covered by the Ediacaran carbonate platform, into an active margin. The geochronological studies of detrital zircons from the metaterrigenous rocks of the Sangilen block demonstrated that the source rocks of these zircons were mostly the Early Neoproterozoic magmatic rocks.
ISSN:0869-5938
1555-6263
DOI:10.1134/S0869593821030035