Skip to Main content Skip to Navigation
Journal articles

Hafnium isotopic disequilibrium during sediment melting and assimilation

Abstract : Identification of juvenile and mature crustal sources in granite formation relies on radiogenic isotopic systems such as Sm-Nd and Lu-Hf and assumes isotope systems reach equilibrium between the melt and residual phases prior to melt extraction. However, we hypothesise disequilibrium melting and residual zircon result in preferential retention of 177 Hf in residues, generating partial melts with higher 176 Hf/ 177 Hf ratios. To test this hypothesis, we evaluate radiogenic isotopic signatures of strongly-peraluminous granites from the Chinese Altai. These granites show Nd-Hf isotopic decoupling and inherited zircons with negative ε Hf (t) values providing evidence for incomplete Hf release. This is consistent with the significant depletions in Zr and Hf. The Chinese data compilation shows that strongly-peraluminous and calcic to calc-alkalic, magnesian metaluminous or ferroan peraluminous (often respectively referred to as Sand I-type) granites show elevated ε Hf (t) relative to the terrestrial Hf-Nd isotopic array. Hf isotope disequilibrium marked by the preferential release of radiogenic Hf is likely ubiquitous during anatexis of zircon-rich protoliths.
Document type :
Journal articles
Complete list of metadatas

Cited literature [178 references]  Display  Hide  Download

https://hal-insu.archives-ouvertes.fr/insu-02453795
Contributor : Isabelle Dubigeon <>
Submitted on : Friday, January 24, 2020 - 9:11:26 AM
Last modification on : Sunday, January 26, 2020 - 1:12:19 AM
Long-term archiving on: : Saturday, April 25, 2020 - 1:26:56 PM

File

Zhang&al-GPL-20.pdf
Publication funded by an institution

Identifiers

Collections

Citation

C. Zhang, D. Liu, X. Zhang, C. Spencer, M. Tang, et al.. Hafnium isotopic disequilibrium during sediment melting and assimilation. Geochemical Perspectives Letters, European Assoication of Geochemistry, 2020, 12, pp.34-39. ⟨10.7185/geochemlet.2001⟩. ⟨insu-02453795⟩

Share

Metrics

Record views

151

Files downloads

154