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

doi:10.1016/j.gr.2014.03.005

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 Publications › Journal Article (refereed) › peer-review

59 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 language	English
Pages (from-to)	1392-1406
Number of pages	15
Journal	Gondwana Research
Volume	27
Issue number	4
Early online date	21 Mar 2014
DOIs	https://doi.org/10.1016/j.gr.2014.03.005
Publication status	Published - Jun 2015
Externally published	Yes

Bibliographical note

Liqin Zhou and Xiao-chao Che of the Beijing SHRIMP Centre provided the zircon CL images, Chun Yang prepared a perfect zircon mount, and Zhiqing Yang and Jianhui Liu tuned the SHRIMP instrument for perfect analyses. Xie Hangqiang kindly assisted in the SHRIMP analyses. Work in the Nd isotope laboratory in St. Petersburg was assisted by L.B. Terent'eva. Jianfeng Gao of the Geological Survey of Canada provided an unpublished Excel-based program to construct the Hf evolution diagrams of Fig. 10, and Figs. 1–3 were drawn by G.P. Pleskach.

Funding

This research was supported by the Russian Foundation for Basic Research (RFBR grants 11-05-92003 and 14-05-00208 ) and is also part of a collaborative study between Mainz University and The University of Hong Kong, funded jointly by the Hong Kong Research Grants Council (RGC 704712P ) and the DAAD/RGC Germany/Hong Kong Joint Research Scheme ( G HK033/12 and PPP).

Keywords

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

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10.1016/j.gr.2014.03.005

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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.",

keywords = "Central Asian Orogenic Belt, Granulite, Nd-Hf isotopes, Tarbagatai microcontinent, Zircon dating",

author = "A. KR{\"O}NER and KOVACH, {V. P.} and KOZAKOV, {I. K.} and T. KIRNOZOVA and P. AZIMOV and J. WONG and GENG, {H. Y.}",

note = "Liqin Zhou and Xiao-chao Che of the Beijing SHRIMP Centre provided the zircon CL images, Chun Yang prepared a perfect zircon mount, and Zhiqing Yang and Jianhui Liu tuned the SHRIMP instrument for perfect analyses. Xie Hangqiang kindly assisted in the SHRIMP analyses. Work in the Nd isotope laboratory in St. Petersburg was assisted by L.B. Terent'eva. Jianfeng Gao of the Geological Survey of Canada provided an unpublished Excel-based program to construct the Hf evolution diagrams of Fig. 10, and Figs. 1–3 were drawn by G.P. Pleskach.",

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doi = "10.1016/j.gr.2014.03.005",

language = "English",

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AU - KRÖNER, A.

AU - KOVACH, V. P.

AU - KOZAKOV, I. K.

AU - KIRNOZOVA, T.

AU - AZIMOV, P.

AU - WONG, J.

AU - GENG, H. Y.

N1 - Liqin Zhou and Xiao-chao Che of the Beijing SHRIMP Centre provided the zircon CL images, Chun Yang prepared a perfect zircon mount, and Zhiqing Yang and Jianhui Liu tuned the SHRIMP instrument for perfect analyses. Xie Hangqiang kindly assisted in the SHRIMP analyses. Work in the Nd isotope laboratory in St. Petersburg was assisted by L.B. Terent'eva. Jianfeng Gao of the Geological Survey of Canada provided an unpublished Excel-based program to construct the Hf evolution diagrams of Fig. 10, and Figs. 1–3 were drawn by G.P. Pleskach.

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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DO - 10.1016/j.gr.2014.03.005

M3 - Journal Article (refereed)

AN - SCOPUS:84928591409

SN - 1342-937X

VL - 27

SP - 1392

EP - 1406

JO - Gondwana Research

JF - Gondwana Research

IS - 4

ER -

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

Bibliographical note

Funding

Keywords

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