Lyell Collection
Geological Society, London, Special Publications
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Niemeijer, A. R.
Right arrow Articles by Spiers, C. J.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Geological Society, London, Special Publications; 2005; v. 245; p. 303-327;
DOI: 10.1144/GSL.SP.2005.245.01.15
© 2005 Geological Society of London

Influence of phyllosilicates on fault strength in the brittle-ductile transition: insights from rock analogue experiments

A. R. Niemeijer & C. J. Spiers

HPT Laboratory, Faculty of Geosciences, Utrecht University, PO Box 80.021, 3508 TA, Utrecht, the Netherlands

(e-mail: niemeyer{at}geo.uu.nl)

Despite the fact that phyllosilicates are ubiquitous in mature fault and shear zones, little is known about the strength of phyllosilicate-bearing fault rocks under brittle-ductile transitional conditions where cataclasis and solution-transfer processes are active. In this study we explored steady-state strength behaviour of a simulated fault rock, consisting of muscovite and halite, using brine as pore fluid. Samples were deformed in a rotary shear apparatus under conditions where cataclasis and solution transfer are known to dominate the deformation behaviour of the halite. It was found that the steady-state strength of these mixtures is dependent on normal stress and sliding velocity. At low velocities (<0.5 µm s–1) the strength increases with velocity and normal stress, and a strong foliation develops. Comparison with previous microphysical models shows that this is a result of the serial operation of pressure solution in the halite grains accommodating frictional sliding over the phyllosilicate foliation. At high velocities (>1 µm s–1), velocity-weakening frictional behaviour occurs along with the development of a structureless cataclastic microstructure. Revision of previous models for the low-velocity behaviour results in a physically realistic description that fits our data well. This is extended to include the possibility of plastic flow in the phyllosilicates and applied to predict steady-state strength profiles for continental fault zones containing foliated quartz-mica fault rocks. The results predict a significant reduction of strength at mid-crustal depths and may have important implications for crustal dynamics and seismogenesis.





This article has been cited by other articles:


Home page
 Geological Society, London, Special PublicationsHome page
C. A. J. Wibberley, G. Yielding, and G. Di Toro
Recent advances in the understanding of fault zone internal structure: a review
Geological Society, London, Special Publications, 2008; 299: 5 - 33.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
J. Imber, R. E. Holdsworth, S. A. F. Smith, S. P. Jefferies, and C. Collettini
Frictional-viscous flow, seismicity and the geology of weak faults: a review and future directions
Geological Society, London, Special Publications, 2008; 299: 151 - 173.
[Abstract] [Full Text] [PDF]