Grain-size reduction of feldspars by fracturing and neocrystallization in a low-grade granitic mylonite and its rheological effect

Jin-Han Lee, Hyeong-Soo Kim, Raehee Han, Haemyeong Jung

Research output: Contribution to journalArticle

32 Citations (Scopus)

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 languageEnglish
Pages (from-to)227-237
Number of pages11
JournalTectonophysics
Volume407
Issue number3-4
DOIs
Publication statusPublished - 2005 Oct 7

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feldspars
mylonite
fracturing
feldspar
grade
plagioclase
grain size
quartz
shear
South Korea
muscovite
ribbons
dislocation creep
free energy
rocks
greenschist facies
disequilibrium
shear zone
energy
effect

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Geophysics

Cite this

Grain-size reduction of feldspars by fracturing and neocrystallization in a low-grade granitic mylonite and its rheological effect. / Lee, Jin-Han; Kim, Hyeong-Soo; Han, Raehee; Jung, Haemyeong.

In: Tectonophysics, Vol. 407, No. 3-4, 07.10.2005, p. 227-237.

Research output: Contribution to journalArticle

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