Magmatic evolution and crustal recycling for Neoproterozoic strongly peraluminous granitoids from southern China

Hf and O isotopes in zircon

Xiao-Lei Wang*, Jin-Cheng Zhou, Yu-Sheng Wan, Kouki Kitajima, Di Wang, Chloe Bonamici, Jian-Sheng Qiu, Tao Sun

*Corresponding author for this work

Research output: Contribution to journalArticle

130 Citations (Scopus)

Abstract

Zircons can retain a grain-scale record of granitoid compositional evolution that is accessible through microanalysis. In situ U-Pb, Hf and O isotope data yield new insights into the petrogenesis and evolution of the Neoproterozoic strongly peraluminous granitoids of the Jiangnan orogen (JO), southern China. A negative correlation of Th/U versus δ18O is found for most analyses. Some zircons from eastern JO granitoids show δ18O variations of 3-6‰ from core to rim, indicating a dramatic shift toward higher oxygen isotope values by voluminous partial melting of supracrustal rocks and signaling a transition from I-type-like to S-type-like magmas during the later stage of magmatic evolution. This mechanism provides a reasonable explanation why some granitoids have intermediate geochemical features between S-type and I-type granites. Hf isotope trends indicate that a larger proportion of mature continental crust was incorporated into the magma sources of the western JO granitoids, whereas more juvenile arc crust was incorporated into the eastern JO magmas. No significant depleted mantle-derived mafic magma was injected into the JO granitoid magmas. Instead, radiogenic Hf and Nd signatures in JO granitoids reflect incorporated juvenile arc crust and document crustal growth in southern China during the Early Neoproterozoic (ca. 900Ma). Thus, our zircon data suggest that strongly peraluminous granitoids, which are widely regarded as the products of orogenesis that primarily recycle evolved crust, can also record important information about early crustal growth.

Original languageEnglish
Pages (from-to)71-82
Number of pages12
JournalEarth and Planetary Science Letters
Volume366
DOIs
Publication statusPublished - 5 Mar 2013
Externally publishedYes

Keywords

  • Hf and O isotopes
  • clearly defined cores
  • zircon
  • S-type granitoids
  • magmatic evolution
  • Jiangnan orogen

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