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)

34 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

Keywords

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

Fingerprint Dive into the research topics of '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'. Together they form a unique fingerprint.

  • Cite this