Zircon dissolution in a ductile shear zone, Monte Rosa granite gneiss, northern Italy

T. J. Dempster, J.C. Martin, Zoe Shipton

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


The sizes, distributions and shapes of zircon grains within variably deformed granite gneiss from the western Alps have been studied. Zircon shows numerous indicators of a metamorphic response in both the host gneiss and a 5 cm wide continuous ductile shear zone, within which the zircon grain sizes range from <1 μm to >50 μm. However, the very fine grain sizes are virtually absent from grain boundaries. Within this zone, zircons consistently have more rounded and embayed margins, which are interpreted as evidence of dissolution in response to fluid influx during shearing. Zircons are preferentially located near metamorphic muscovite in both the host gneiss and the shear zone and tend to show the poorest crystal shape, indicating that fluids linked to the formation and presence of muscovite may enhance both the crystallization of zircon and its subsequent dissolution. Larger zircon crystals typically show a brittle response to deformation when adjacent to phyllosilicates, with fractures consistently perpendicular to the (001) mica cleavage. The variety of metamorphic behaviour observed for zircon indicates that it may be highly reactive in sub-solidus mid-crustal metamorphic environments.
Original languageEnglish
Pages (from-to)971-986
Number of pages16
JournalMineralogical Magazine
Issue number4
Publication statusPublished - Aug 2008


  • deformation
  • zircon
  • shear zone
  • metamorphism
  • dissolution


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