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.
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Ganguly, J., Hensen, B.J. & Cheng, W. 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. J Earth Syst Sci 110, 305–312 (2001). https://doi.org/10.1007/BF02702897
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DOI: https://doi.org/10.1007/BF02702897