Abstract
Feldspar grain-size reduction occurred due to the fracturing of plagioclase and K-feldspar, myrmekite formation and neocrystallization of albitic plagioclase along shear fractures of K-feldspar porphyroclasts in the leucocratic granitic rocks from the Yecheon shear zone of South Korea that was deformed under a middle greenschist-facies condition. The neocrystallization of albitic plagioclase was induced by strain energy adjacent to the shear fractures and by chemical free energy due to the compositional disequilibrium between infiltrating Na-rich fluid and host K-feldspar. With increasing deformation from protomylonite to mylonite, alternating layers of feldspar, quartz and muscovite developed. The fine-grained feldspar-rich layers were deformed dominantly by granular flow, while quartz ribbons were deformed by dislocation creep. With layer development and a more distributed strain in the mylonite, lower stresses in the quartz-rich layers resulted in a larger size of dynamically recrystallized quartz grains than that of the protomylonite.
Original language | English |
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Pages (from-to) | 227-237 |
Number of pages | 11 |
Journal | Tectonophysics |
Volume | 407 |
Issue number | 3-4 |
DOIs | |
Publication status | Published - 2005 Oct 7 |
Keywords
- Dynamic recrystallization
- Grain-size reduction
- Granitic mylonite
- Granular flow
- Yecheon shear zone
ASJC Scopus subject areas
- Geophysics
- Earth-Surface Processes