| Abstract: | The frictional strength of brucite gouge has been measured at hydrothermal conditions to 450 ?C. At room temperature, brucite has a coefficient of friction, ? 0.30, making it one of the weakest minerals identified to date. With increasing temperature at a constant effective normal stress, the coefficient of friction of brucite decreases to a minimum of ? 0.20 near 300 ?C, and ? 0.22-0.24 in the temperature range 350-450 ?C. Brucite has a sheeted crystal structure, and its low frictional strength may be attributed to the relatively weak bonds between the layers. In addition, the temperature dependence of ? to 300 ?C can be explained in terms of the anomalously large coefficient of thermal expansion of brucite, which will further weaken the interlayer bonds. Brucite is a common constituent of serpentinite, and at 300 ?C, where brucite is weakest, all the major serpentine minerals have ? 0.5. The maximum expected brucite content of a serpentinite is close to 20% by weight or volume. That amount of disseminated brucite will lower the coefficient of friction of serpentinite by 10-15% in the deeper parts of the seismogenic zone. However, the effect will be much greater if shear can be concentrated along brucite-lined slip surfaces in the serpentinite body. |
| Genre: | USGS Numbered Series |
| ProdID: | 31472 |
| Citation Author: | Moore, Diane E.; Lockner, David A.; Iwata, K.; Tanaka, H.; Byerlee, J. D. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | 14 p. |
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| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 2001-320 |
| Citation Search Results Text: | How brucite may affect the frictional properties of serpentinite; 2001; OFR; 2001-320; Moore, Diane E.; Lockner, David A.; Iwata, K.; Tanaka, H.; Byerlee, J. D. |
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| Citation Year: | 2001 |
| Type: | citation/reference |
| Text: | How brucite may affect the frictional properties of serpentinite; 2001; OFR; 2001-320; Moore, Diane E.; Lockner, David A.; Iwata, K.; Tanaka, H.; Byerlee, J. D. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/usgs_thumb.jpg |
| URL (INDEX PAGE): | http://geopubs.wr.usgs.gov/open-file/of01-320/ |
| Date Other: | Fri, 1 Mar 2002 00:00 -0600 |
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