Zircon ages and Nd-Hf isotopes in UHT granulites of the Ider Complex : A cratonic terrane within the Central Asian Orogenic Belt in NW Mongolia

A. KRÖNER*, V. P. KOVACH, I. K. KOZAKOV, T. KIRNOZOVA, P. AZIMOV, J. WONG, H. Y. GENG

*Corresponding author for this work

Research output: Journal PublicationsJournal Article (refereed)Researchpeer-review

27 Citations (Scopus)

Abstract

The Ider Complex of the Tarbagatai Block in northwestern Mongolia is part of a Precambrian microcontinental terrane in the Central Asian Orogen Belt and has experienced a polymetamorphic tectono-metamorphic evolution. We have investigated an enderbitic gneiss, derived from a quartz diorite and a charnockite, derived from a leucogranite, and zircon SHRIMP data reveal late Archaean protolith ages of 2520-2546. Ma for these rocks. Metamorphic overgrowth on these zircons as well as newly-formed metamorphic zircons document a high-temperature metamorphic event (T = 930-950. °C) at about 1855-1860. Ma. Nd whole-rock isotopic systematics show these and other gneisses of the Ider Complex straddling the CHUR-line in a Nd isotope evolution diagram, suggesting both crustal reworking and input of some juvenile material, with Nd model ages ranging between ca. 2.5 and 3.1. Ga. Hf-in-zircon isotopic data provide a similar pattern and also yielded Archaean Hf crustal model ages. The metamorphic zircons seem to have inherited their Hf isotopic composition from the igneous grains, suggesting a complex process of dissolution, transportation, and re-precipitation involving a fluid phase during high-grade metamorphism. The zircon age patterns do not make it possible to unambiguously assign the Tarbagatai Block to any of the cratons bordering the Central Asian Orogenic Belt, since age peaks at ca. 2520-2550 and ca. 1860. Ma are common in the Siberian, North China and Tarim cratons.

Original languageEnglish
Pages (from-to)1392-1406
Number of pages15
JournalGondwana Research
Volume27
Issue number4
Early online date21 Mar 2014
DOIs
Publication statusPublished - Jun 2015
Externally publishedYes

Fingerprint

orogenic belt
terrane
zircon
isotope
craton
Archean
charnockite
leucogranite
diorite
protolith
reworking
rock
gneiss
Precambrian
isotopic composition
metamorphism
diagram
dissolution
quartz
fluid

Keywords

  • Central Asian Orogenic Belt
  • Granulite
  • Nd-Hf isotopes
  • Tarbagatai microcontinent
  • Zircon dating

Cite this

KRÖNER, A. ; KOVACH, V. P. ; KOZAKOV, I. K. ; KIRNOZOVA, T. ; AZIMOV, P. ; WONG, J. ; GENG, H. Y. / Zircon ages and Nd-Hf isotopes in UHT granulites of the Ider Complex : A cratonic terrane within the Central Asian Orogenic Belt in NW Mongolia. In: Gondwana Research. 2015 ; Vol. 27, No. 4. pp. 1392-1406.
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title = "Zircon ages and Nd-Hf isotopes in UHT granulites of the Ider Complex : A cratonic terrane within the Central Asian Orogenic Belt in NW Mongolia",
abstract = "The Ider Complex of the Tarbagatai Block in northwestern Mongolia is part of a Precambrian microcontinental terrane in the Central Asian Orogen Belt and has experienced a polymetamorphic tectono-metamorphic evolution. We have investigated an enderbitic gneiss, derived from a quartz diorite and a charnockite, derived from a leucogranite, and zircon SHRIMP data reveal late Archaean protolith ages of 2520-2546. Ma for these rocks. Metamorphic overgrowth on these zircons as well as newly-formed metamorphic zircons document a high-temperature metamorphic event (T = 930-950. °C) at about 1855-1860. Ma. Nd whole-rock isotopic systematics show these and other gneisses of the Ider Complex straddling the CHUR-line in a Nd isotope evolution diagram, suggesting both crustal reworking and input of some juvenile material, with Nd model ages ranging between ca. 2.5 and 3.1. Ga. Hf-in-zircon isotopic data provide a similar pattern and also yielded Archaean Hf crustal model ages. The metamorphic zircons seem to have inherited their Hf isotopic composition from the igneous grains, suggesting a complex process of dissolution, transportation, and re-precipitation involving a fluid phase during high-grade metamorphism. The zircon age patterns do not make it possible to unambiguously assign the Tarbagatai Block to any of the cratons bordering the Central Asian Orogenic Belt, since age peaks at ca. 2520-2550 and ca. 1860. Ma are common in the Siberian, North China and Tarim cratons.",
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Zircon ages and Nd-Hf isotopes in UHT granulites of the Ider Complex : A cratonic terrane within the Central Asian Orogenic Belt in NW Mongolia. / KRÖNER, A.; KOVACH, V. P.; KOZAKOV, I. K.; KIRNOZOVA, T.; AZIMOV, P.; WONG, J.; GENG, H. Y.

In: Gondwana Research, Vol. 27, No. 4, 06.2015, p. 1392-1406.

Research output: Journal PublicationsJournal Article (refereed)Researchpeer-review

TY - JOUR

T1 - Zircon ages and Nd-Hf isotopes in UHT granulites of the Ider Complex : A cratonic terrane within the Central Asian Orogenic Belt in NW Mongolia

AU - KRÖNER, A.

AU - KOVACH, V. P.

AU - KOZAKOV, I. K.

AU - KIRNOZOVA, T.

AU - AZIMOV, P.

AU - WONG, J.

AU - GENG, H. Y.

PY - 2015/6

Y1 - 2015/6

N2 - The Ider Complex of the Tarbagatai Block in northwestern Mongolia is part of a Precambrian microcontinental terrane in the Central Asian Orogen Belt and has experienced a polymetamorphic tectono-metamorphic evolution. We have investigated an enderbitic gneiss, derived from a quartz diorite and a charnockite, derived from a leucogranite, and zircon SHRIMP data reveal late Archaean protolith ages of 2520-2546. Ma for these rocks. Metamorphic overgrowth on these zircons as well as newly-formed metamorphic zircons document a high-temperature metamorphic event (T = 930-950. °C) at about 1855-1860. Ma. Nd whole-rock isotopic systematics show these and other gneisses of the Ider Complex straddling the CHUR-line in a Nd isotope evolution diagram, suggesting both crustal reworking and input of some juvenile material, with Nd model ages ranging between ca. 2.5 and 3.1. Ga. Hf-in-zircon isotopic data provide a similar pattern and also yielded Archaean Hf crustal model ages. The metamorphic zircons seem to have inherited their Hf isotopic composition from the igneous grains, suggesting a complex process of dissolution, transportation, and re-precipitation involving a fluid phase during high-grade metamorphism. The zircon age patterns do not make it possible to unambiguously assign the Tarbagatai Block to any of the cratons bordering the Central Asian Orogenic Belt, since age peaks at ca. 2520-2550 and ca. 1860. Ma are common in the Siberian, North China and Tarim cratons.

AB - The Ider Complex of the Tarbagatai Block in northwestern Mongolia is part of a Precambrian microcontinental terrane in the Central Asian Orogen Belt and has experienced a polymetamorphic tectono-metamorphic evolution. We have investigated an enderbitic gneiss, derived from a quartz diorite and a charnockite, derived from a leucogranite, and zircon SHRIMP data reveal late Archaean protolith ages of 2520-2546. Ma for these rocks. Metamorphic overgrowth on these zircons as well as newly-formed metamorphic zircons document a high-temperature metamorphic event (T = 930-950. °C) at about 1855-1860. Ma. Nd whole-rock isotopic systematics show these and other gneisses of the Ider Complex straddling the CHUR-line in a Nd isotope evolution diagram, suggesting both crustal reworking and input of some juvenile material, with Nd model ages ranging between ca. 2.5 and 3.1. Ga. Hf-in-zircon isotopic data provide a similar pattern and also yielded Archaean Hf crustal model ages. The metamorphic zircons seem to have inherited their Hf isotopic composition from the igneous grains, suggesting a complex process of dissolution, transportation, and re-precipitation involving a fluid phase during high-grade metamorphism. The zircon age patterns do not make it possible to unambiguously assign the Tarbagatai Block to any of the cratons bordering the Central Asian Orogenic Belt, since age peaks at ca. 2520-2550 and ca. 1860. Ma are common in the Siberian, North China and Tarim cratons.

KW - Central Asian Orogenic Belt

KW - Granulite

KW - Nd-Hf isotopes

KW - Tarbagatai microcontinent

KW - Zircon dating

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U2 - 10.1016/j.gr.2014.03.005

DO - 10.1016/j.gr.2014.03.005

M3 - Journal Article (refereed)

VL - 27

SP - 1392

EP - 1406

JO - Gondwana Research

JF - Gondwana Research

SN - 1342-937X

IS - 4

ER -