The structure of grain boundaries in granite-origin ultramylonite studied by high-resolution electron microscopy

T. Hiraga, Toshiro Nagase, M. Akizuki

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The structure of grain boundaries in a granite-origin ultramylonite, composed mainly of fine-grained feldspar and quartz, was studied by high-resolution electron microscopy (HREM). At most of the boundaries, not only between the same minerals but also between different minerals, lattice fringes in adjacent grains meet at the interface with no other appreciable phases. In these boundaries, some of the straight segments correspond to a low-index plane of one of the connected grains. Boundaries containing voids, with a spheroidal shape elongated along the boundaries, were observed only between quartz grains. It is suggested that these boundaries were formed by healing of microcracks. The structural width of major boundaries, deduced from lattice-fringe imaging, is less than about 0.5 nm.

Original languageEnglish
Pages (from-to)617-623
Number of pages7
JournalPhysics and Chemistry of Minerals
Volume26
Issue number8
DOIs
Publication statusPublished - 1999 Sep 1

Keywords

  • Grain boundary
  • High-resolution electron microscopy
  • Lattice fringe
  • Ultramylonite

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Materials Science(all)

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