Morphology of intergranular pores and wetting angles in pelitic schists studied by transmission electron microscopy

Takehiko Hiraga, Osamu Nishikawa, Toshiro Nagase, Mizuhiko Akizuki

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

In pelitic schists composed mainly of quartz and albite grains, the morphology of intergranular pores, which were filled with water, was studied by transmission electron microscopy (TEM). Although some pores are defined by crystallographic planes (F-face), most of their form has an ideal shape determined by interface tensions between grains and fluid. High-resolution TEM observations demonstrate that pore-free regions at grain boundaries are tight even at the nanometer scale, showing that the wetting angle is larger than 0° in this rock. The pore distribution in two-grain junctions can be compared to a "necklace microstructure" developed by instability of a fluid film along the boundary induced by microcracking. Wetting angles for pores located at grain edges of quartz and albite decrease in the order albite/ albite, quartz/quartz, and quartz/albite. The quartz/ quartz wetting angle in a calcite-free sample is smaller than that in a calcite-containing sample. This angle also changes due to grain misorientation. Our results confirm that solid-solid and solid-fluid interfacial energies control the geometry of intergranular fluid in natural rocks.

Original languageEnglish
Pages (from-to)613-622
Number of pages10
JournalContributions to Mineralogy and Petrology
Volume141
Issue number5
DOIs
Publication statusPublished - 2001 Jan 1

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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