Palaeozoic arc magmatism in the Central Asian Orogenic Belt of Kazakhstan: SHRIMP zircon ages and whole-rock Nd isotopic systematics

A. Kröner, E. Hegner, B. Lehmann, J. Heinhorst, Michael Wingate, D.Y. Liu, P. Ermelov

    Research output: Contribution to journalArticle

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    Abstract

    Early Palaeozoic tonalite to granodiorite intrusions in northern Kazakhstan are associated with lode gold mineralization and have SHRIMP zircon ages of 457.3 +/- 6.6 Ma (Aksu), 452.9 +/- 5.6 Ma and 447.4 +/- 5A Ma (both Zholymbet). The Stepnyak intrusion contains large xenoliths with an age of 480.6 +/- 5.0 Ma. One early Palaeozoic zircon from. a porphyritic diorite at Stepnyak has a core with a near-concordant Pb-207/Pb-206 age of 3888 +/- 1.5 Ma, whereas other xenocrystic grains are between 983 and 2698 Ma old. The early Archaean age is probably inherited from unexposed basement of the Kokchetav Massif and represents the oldest crustal material so far known from the Asian continent. It appears that the Aksu, Zholimbet and Stepnyak granitoids were emplaced in the late Ordovician in an Andean- or Japan-type continental arc environment on the margin of the Kokchetav Massif.Late Palaeozoic granitoids in central Kazakhstan have Devonian zircon ages of 407.1 +/- 3.9, 381.1 +/- 3.1 and 369.2 +/- 4.9 Ma, whereas the youngest sample from the Topar Massif has a late Carboniferous emplacement age of 314.1 +/- 5.1 Ma. Initial epsilon(Nd) values range from +5 to -1 corresponding to Nd-model ages of 1.1-0.6 Ga. The isotopic data. are similar to those of other Phanerozoic granitoids of the Central Asian Orogenic Belt and corroborate melting of predominantly juvenile crustal protoliths. Our data also confirm that Devonian and Carboniferous are magmatism in central Kazakhstan assimilated older and already accreted island arc systems, yet is derived from primitive sources, probably in a subduction setting.The range of epsilon(Nd) values with corresponding Nd mean crustal residence ages in the range of 0.6-1.1 Ga for most samples indicates variable recycling of late Proterozoic largely juvenile continental crust in the formation of the Palaeozoic magmatic arcs of central Kazakhstan. The orogenic evolution terminated with Permian anorogenic, rift-related alkaline granite magmatism (epsilon(Nd) = +2 to +8) which reflects melting of juvenile, mantle-derived lower crust. (c) 2007 Elsevier Ltd. All rights reserved.
    Original languageEnglish
    Pages (from-to)118-130
    JournalJournal of Asian Earth Sciences
    Volume32
    DOIs
    Publication statusPublished - 2008

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    orogenic belt
    magmatism
    zircon
    Paleozoic
    rock
    melting
    continental arc
    tonalite
    diorite
    Phanerozoic
    protolith
    granodiorite
    lower crust
    continental crust
    island arc
    Archean
    Ordovician
    Proterozoic
    emplacement
    Permian

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    @article{0ee51e58bae64e1090b5029fc8edfcc8,
    title = "Palaeozoic arc magmatism in the Central Asian Orogenic Belt of Kazakhstan: SHRIMP zircon ages and whole-rock Nd isotopic systematics",
    abstract = "Early Palaeozoic tonalite to granodiorite intrusions in northern Kazakhstan are associated with lode gold mineralization and have SHRIMP zircon ages of 457.3 +/- 6.6 Ma (Aksu), 452.9 +/- 5.6 Ma and 447.4 +/- 5A Ma (both Zholymbet). The Stepnyak intrusion contains large xenoliths with an age of 480.6 +/- 5.0 Ma. One early Palaeozoic zircon from. a porphyritic diorite at Stepnyak has a core with a near-concordant Pb-207/Pb-206 age of 3888 +/- 1.5 Ma, whereas other xenocrystic grains are between 983 and 2698 Ma old. The early Archaean age is probably inherited from unexposed basement of the Kokchetav Massif and represents the oldest crustal material so far known from the Asian continent. It appears that the Aksu, Zholimbet and Stepnyak granitoids were emplaced in the late Ordovician in an Andean- or Japan-type continental arc environment on the margin of the Kokchetav Massif.Late Palaeozoic granitoids in central Kazakhstan have Devonian zircon ages of 407.1 +/- 3.9, 381.1 +/- 3.1 and 369.2 +/- 4.9 Ma, whereas the youngest sample from the Topar Massif has a late Carboniferous emplacement age of 314.1 +/- 5.1 Ma. Initial epsilon(Nd) values range from +5 to -1 corresponding to Nd-model ages of 1.1-0.6 Ga. The isotopic data. are similar to those of other Phanerozoic granitoids of the Central Asian Orogenic Belt and corroborate melting of predominantly juvenile crustal protoliths. Our data also confirm that Devonian and Carboniferous are magmatism in central Kazakhstan assimilated older and already accreted island arc systems, yet is derived from primitive sources, probably in a subduction setting.The range of epsilon(Nd) values with corresponding Nd mean crustal residence ages in the range of 0.6-1.1 Ga for most samples indicates variable recycling of late Proterozoic largely juvenile continental crust in the formation of the Palaeozoic magmatic arcs of central Kazakhstan. The orogenic evolution terminated with Permian anorogenic, rift-related alkaline granite magmatism (epsilon(Nd) = +2 to +8) which reflects melting of juvenile, mantle-derived lower crust. (c) 2007 Elsevier Ltd. All rights reserved.",
    author = "A. Kr{\"o}ner and E. Hegner and B. Lehmann and J. Heinhorst and Michael Wingate and D.Y. Liu and P. Ermelov",
    year = "2008",
    doi = "10.1016/j.jseaes.2007.10.013",
    language = "English",
    volume = "32",
    pages = "118--130",
    journal = "Journal of Asian Earth Sciences",
    issn = "1367-9120",
    publisher = "Elsevier",

    }

    Palaeozoic arc magmatism in the Central Asian Orogenic Belt of Kazakhstan: SHRIMP zircon ages and whole-rock Nd isotopic systematics. / Kröner, A.; Hegner, E.; Lehmann, B.; Heinhorst, J.; Wingate, Michael; Liu, D.Y.; Ermelov, P.

    In: Journal of Asian Earth Sciences, Vol. 32, 2008, p. 118-130.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Palaeozoic arc magmatism in the Central Asian Orogenic Belt of Kazakhstan: SHRIMP zircon ages and whole-rock Nd isotopic systematics

    AU - Kröner, A.

    AU - Hegner, E.

    AU - Lehmann, B.

    AU - Heinhorst, J.

    AU - Wingate, Michael

    AU - Liu, D.Y.

    AU - Ermelov, P.

    PY - 2008

    Y1 - 2008

    N2 - Early Palaeozoic tonalite to granodiorite intrusions in northern Kazakhstan are associated with lode gold mineralization and have SHRIMP zircon ages of 457.3 +/- 6.6 Ma (Aksu), 452.9 +/- 5.6 Ma and 447.4 +/- 5A Ma (both Zholymbet). The Stepnyak intrusion contains large xenoliths with an age of 480.6 +/- 5.0 Ma. One early Palaeozoic zircon from. a porphyritic diorite at Stepnyak has a core with a near-concordant Pb-207/Pb-206 age of 3888 +/- 1.5 Ma, whereas other xenocrystic grains are between 983 and 2698 Ma old. The early Archaean age is probably inherited from unexposed basement of the Kokchetav Massif and represents the oldest crustal material so far known from the Asian continent. It appears that the Aksu, Zholimbet and Stepnyak granitoids were emplaced in the late Ordovician in an Andean- or Japan-type continental arc environment on the margin of the Kokchetav Massif.Late Palaeozoic granitoids in central Kazakhstan have Devonian zircon ages of 407.1 +/- 3.9, 381.1 +/- 3.1 and 369.2 +/- 4.9 Ma, whereas the youngest sample from the Topar Massif has a late Carboniferous emplacement age of 314.1 +/- 5.1 Ma. Initial epsilon(Nd) values range from +5 to -1 corresponding to Nd-model ages of 1.1-0.6 Ga. The isotopic data. are similar to those of other Phanerozoic granitoids of the Central Asian Orogenic Belt and corroborate melting of predominantly juvenile crustal protoliths. Our data also confirm that Devonian and Carboniferous are magmatism in central Kazakhstan assimilated older and already accreted island arc systems, yet is derived from primitive sources, probably in a subduction setting.The range of epsilon(Nd) values with corresponding Nd mean crustal residence ages in the range of 0.6-1.1 Ga for most samples indicates variable recycling of late Proterozoic largely juvenile continental crust in the formation of the Palaeozoic magmatic arcs of central Kazakhstan. The orogenic evolution terminated with Permian anorogenic, rift-related alkaline granite magmatism (epsilon(Nd) = +2 to +8) which reflects melting of juvenile, mantle-derived lower crust. (c) 2007 Elsevier Ltd. All rights reserved.

    AB - Early Palaeozoic tonalite to granodiorite intrusions in northern Kazakhstan are associated with lode gold mineralization and have SHRIMP zircon ages of 457.3 +/- 6.6 Ma (Aksu), 452.9 +/- 5.6 Ma and 447.4 +/- 5A Ma (both Zholymbet). The Stepnyak intrusion contains large xenoliths with an age of 480.6 +/- 5.0 Ma. One early Palaeozoic zircon from. a porphyritic diorite at Stepnyak has a core with a near-concordant Pb-207/Pb-206 age of 3888 +/- 1.5 Ma, whereas other xenocrystic grains are between 983 and 2698 Ma old. The early Archaean age is probably inherited from unexposed basement of the Kokchetav Massif and represents the oldest crustal material so far known from the Asian continent. It appears that the Aksu, Zholimbet and Stepnyak granitoids were emplaced in the late Ordovician in an Andean- or Japan-type continental arc environment on the margin of the Kokchetav Massif.Late Palaeozoic granitoids in central Kazakhstan have Devonian zircon ages of 407.1 +/- 3.9, 381.1 +/- 3.1 and 369.2 +/- 4.9 Ma, whereas the youngest sample from the Topar Massif has a late Carboniferous emplacement age of 314.1 +/- 5.1 Ma. Initial epsilon(Nd) values range from +5 to -1 corresponding to Nd-model ages of 1.1-0.6 Ga. The isotopic data. are similar to those of other Phanerozoic granitoids of the Central Asian Orogenic Belt and corroborate melting of predominantly juvenile crustal protoliths. Our data also confirm that Devonian and Carboniferous are magmatism in central Kazakhstan assimilated older and already accreted island arc systems, yet is derived from primitive sources, probably in a subduction setting.The range of epsilon(Nd) values with corresponding Nd mean crustal residence ages in the range of 0.6-1.1 Ga for most samples indicates variable recycling of late Proterozoic largely juvenile continental crust in the formation of the Palaeozoic magmatic arcs of central Kazakhstan. The orogenic evolution terminated with Permian anorogenic, rift-related alkaline granite magmatism (epsilon(Nd) = +2 to +8) which reflects melting of juvenile, mantle-derived lower crust. (c) 2007 Elsevier Ltd. All rights reserved.

    U2 - 10.1016/j.jseaes.2007.10.013

    DO - 10.1016/j.jseaes.2007.10.013

    M3 - Article

    VL - 32

    SP - 118

    EP - 130

    JO - Journal of Asian Earth Sciences

    JF - Journal of Asian Earth Sciences

    SN - 1367-9120

    ER -