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Gallery of melt textures developed in Westerly Granite during high-pressure triaxial friction experiments

Open-File Report 2016-1059
By: , , , and 
https://doi.org/10.3133/ofr20161059

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Introduction

Melting occurred during stick-slip faulting of granite blocks sheared at room-dry, room-temperature conditions in a triaxial apparatus at 200–400 megapascals (MPa) confining pressure. Petrographic examinations of melt textures focused largely on the 400-MPa run products. This report presents an overview of the petrographic data collected on those samples, followed by brief descriptions of annotated versions of all the images.

Scanning electron microscope (SEM) images of the starting materials and the three examined 400-MPa samples are presented in this report. Secondary-electron (SE) and backscattered-electron (BSE) imaging techniques were used on different samples. The SE images look down on the sawcut surfaces, yielding topographic and three-dimensional textural information. The BSE imaging was done on samples cut to provide cross-sectional views of the glass-filled shear band (or zone) that developed along the sawcut. Brightness in the BSE images increases with increasing mean atomic number of the material. Additional chemical information about the quenched melt and adjoining minerals was obtained using the energy dispersive system of the SEM during BSE examinations. However, the very narrow shear-band thicknesses and common occurrence of very fine lamellar compositional layering limited the usefulness of this technique for estimating melt chemistry.

Suggested Citation

Moore, D.E., Lockner, D.A., Kilgore, B.D., and Beeler, N.M., 2016, Gallery of melt textures developed in Westerly Granite during high-pressure triaxial friction experiments: U.S. Geological Survey Open-File Report 2016–1059, 75 p., http://dx.doi.org/10.3133/ofr20161059.

ISSN: 2331-1258 (online)

Table of Contents

  • Introduction
  • Starting Material
  • Overview of Melt Textures
  • Discussion
  • References
  • Image Gallery
Publication type Report
Publication Subtype USGS Numbered Series
Title Gallery of melt textures developed in Westerly Granite during high-pressure triaxial friction experiments
Series title Open-File Report
Series number 2016-1059
DOI 10.3133/ofr20161059
Year Published 2016
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Earthquake Science Center
Description iv, 75 p.
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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