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 Maltman, Alex. J.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Geological Society, London, Special Publications; 1987; v. 29; p. 77-87;
DOI: 10.1144/GSL.SP.1987.029.01.08
© 1987 Geological Society of London

Part I Theory and Experimental

Shear zones in argillaceous sediments—an experimental study

Alex. J. Maltman

Department of Geology, University College of Wales, Aberystwyth SY23 3DB, Wales

Experimental deformation of water-rich argillaceous sediments has shown that they deform not by pervasive homogeneous flow, as has sometimes been surmised in the past, but by intense slippage within very narrow, discrete zones of shear. These shear zones enable large total strains to be accomplished whilst leaving the bulk of the material undisturbed. Macroscopically the zones are shiny, finely-grooved planes which may be stepped where sub-structures intersect them. Under the microscope the zones are seen to result from pronounced particle reorientation into sub-parallelism with the zone margins, presumably by slippage at the grain scale. The zones commonly curve and anastomose, and various sub-fabrics may be discernible. Although the details vary, the shear zones are strikingly consistent throughout the range of experimental conditions.

In specimens with 15% water content, the shear zones lack cohesion and are analogous to shear fractures in brittle rocks. Between approximately 15–45% water content the same overall geometry persists, but the shear zones maintain cohesion. At greater water contents, up to at least 60%, the clay sediments are extremely weak and although they may appear to be undergoing pervasive flow, microscopic examination reveals that even here arrays of short, narrow zones of concentrated displacement are being generated.





This article has been cited by other articles:


Home page
 Geological Society, London, Special PublicationsHome page
E. Casciello, M. Cesarano, and J. W. Cosgrove
Shear deformation of pelitic rocks in a large-scale natural fault
Geological Society, London, Special Publications, 2004; 224: 113 - 125.
[Abstract] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
G. Owen
Load structures: gravity-driven sediment mobilization in the shallow subsurface
Geological Society, London, Special Publications, 2003; 216: 21 - 34.
[Abstract] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
B. Hubbard and A. Maltman
Laboratory investigations of the strength, static hydraulic conductivity and dynamic hydraulic conductivity of glacial sediments
Geological Society, London, Special Publications, 2000; 176: 231 - 242.
[Abstract] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
F. M. Van der Wateren, S. J. Kluiving, and L. R. Bartek
Kinematic indicators of subglacial shearing
Geological Society, London, Special Publications, 2000; 176: 259 - 278.
[Abstract] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
M. G. Peters and A. J. Maltman
Insights into the hydraulic performance of landfill-lining clays during deformation
Geological Society, London, Special Publications, 1999; 158: 97 - 106.
[Abstract] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
E.L. Stephenson, A.J. Maltman, and R.J. Knipe
Fluid flow in actively deforming sediments: 'dynamic permeability' in accretionary prisms
Geological Society, London, Special Publications, 1994; 78: 113 - 125.
[Abstract] [PDF]