Evolution history of the Neoproterozoic eclogite-bearing complex of the Muya dome (Central Asian Orogenic Belt): Constraints from zircon U-Pb age, Hf and whole-rock Nd isotopes

V. S. Shatsky, V. G. Malkovets, E. A. Belousova, S. Yu Skuzovatov

    Research output: Contribution to journalArticle

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    Abstract

    U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a 207Pb/206Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of eHf(t) values (from +13.9 to -15.3) and TCDM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of eHf(t) (+11.6 to -0.7) and TCDM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with eNd(t) values ranging from -3.5 to +3.6 and tNd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt.

    Original languageEnglish
    Pages (from-to)1-11
    Number of pages11
    JournalPrecambrian Research
    Volume261
    DOIs
    Publication statusPublished - May 1 2015

    Fingerprint

    Bearings (structural)
    Domes
    eclogite
    orogenic belt
    Isotopes
    dome
    zircon
    Rocks
    isotope
    history
    rock
    Zoning
    schist
    zoning
    Garnets
    biotite
    garnet
    isotopic composition
    Geochronology
    resetting

    Keywords

    • Central Asian Orogenic Belt
    • Continental subduction
    • Hf isotopes
    • U-Pb dating
    • Zircon

    ASJC Scopus subject areas

    • Geochemistry and Petrology
    • Geology

    Cite this

    Evolution history of the Neoproterozoic eclogite-bearing complex of the Muya dome (Central Asian Orogenic Belt) : Constraints from zircon U-Pb age, Hf and whole-rock Nd isotopes. / Shatsky, V. S.; Malkovets, V. G.; Belousova, E. A.; Skuzovatov, S. Yu.

    In: Precambrian Research, Vol. 261, 01.05.2015, p. 1-11.

    Research output: Contribution to journalArticle

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    abstract = "U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a 207Pb/206Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of eHf(t) values (from +13.9 to -15.3) and TCDM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of eHf(t) (+11.6 to -0.7) and TCDM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with eNd(t) values ranging from -3.5 to +3.6 and tNd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt.",
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    AU - Shatsky, V. S.

    AU - Malkovets, V. G.

    AU - Belousova, E. A.

    AU - Skuzovatov, S. Yu

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    N2 - U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a 207Pb/206Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of eHf(t) values (from +13.9 to -15.3) and TCDM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of eHf(t) (+11.6 to -0.7) and TCDM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with eNd(t) values ranging from -3.5 to +3.6 and tNd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt.

    AB - U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a 207Pb/206Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of eHf(t) values (from +13.9 to -15.3) and TCDM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of eHf(t) (+11.6 to -0.7) and TCDM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with eNd(t) values ranging from -3.5 to +3.6 and tNd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt.

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    KW - Continental subduction

    KW - Hf isotopes

    KW - U-Pb dating

    KW - Zircon

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