• Reaction texture and Fe-Mg zoning in granulite garnet from SØstrene Island, Antarctica: Modeling and constraint on the time scale of metamorphism during the Pan-African collisional event

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    • Keywords

       

      Time scale; tectono-metamorphism; diffusion; reaction

    • Abstract

       

      Garnets from the S⊍strene island, Antarctica, show reaction textures corresponding to two metamorphic episodes, one at c. 1000 Ma (M1) and the other at c. 500 Ma (M2). The latter is associated with a Pan-African tectono-metamorphic event that has been interpreted to represent a continent-continent collision followed by extensional collapse. Reaction-diffusion modeling of the compositional zoning of garnet associated with the development of reaction texture during M2 yields a time scale of ∼ 5–16 Myr for the duration of the peak of this overprinting metamorphism at ∼ 730 ± 20‡C. The associated velocity of the reaction front is ∼∼ 5.0-1.6Μm/Myr. The inferred duration of peak metamorphism during the Pan-African event seems to be in good agreement with the available U-Pb SHRIMP ages of zircon and monazite that may be interpreted to have formed at the beginning and end stages of crystallization of granite during the metamorphic peak.

    • Author Affiliations

       

      J Ganguly1 B J Hensen2 W Cheng1

      1. Department of Geosciences, University of Arizona, Tucson, AZ - 85721, USA
      2. Department of Applied Geology, University of New South Wales, Kensington, NSW - 2033, Australia
    • Dates

       
  • Journal of Earth System Science | News

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