Lyell Collection
Journal of the Geological Society
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
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 Web of Science (2)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Dehandschutter, B.
Right arrow Articles by Wouters, L.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Journal of the Geological Society; 2005; v. 162; issue.5; p. 801-813;
DOI: 10.1144/0016-764904-093
© 2005 Geological Society of London

Original Article

Volumetric matrix strain related to intraformational faulting in argillaceous sediments

B. Dehandschutter1,2, P. Gaviglio3, J. P. Sizun3, M. Sintubin1, S. Vandycke4, N. Vandenberghe5 & L. Wouters6

1 1Geodynamics & Geofluids Group, Katholieke Universiteit Leuven, Redingenstraat 16, 3000 Leuven, Belgium
2 2Present address: International Bureau for Environmental Studies (IBES), Ortar Depauwstraat 49, B-3080 Tervuren, Belgium (e-mail: bodehand@ibes.be)
3 3EA 2642 Géosciences, Université de Franche-Comté, 16, route de Gray, F-25030 Besançon cédex, France
4 4Géologie Fondamentale et Appliquée, Faculté Polytechnique de Mons, 9, rue de Houdain, 7000 Mons, Belgium
5 5Stratigraphy Group, Katholieke Universiteit Leuven, Redingenstraat 16, 3000 Leuven, Belgium
6 6ONDRAF/NIRAS, Kunstlaan 14, 1210 Brussels, Belgium

Soft-sediment deformation involves complex interactions between discrete fracturing and diffuse bulk strain, described in terms of volume change and shear strain in a critical state mechanics framework. This study reports on a mesoscale normal fault zone, intraformational in Oligocene argillaceous sediments from the Boom Formation (Belgium), containing several metre-scale normal fault strands. They form either discrete fault planes or decimetre-wide shear zones with internal fabric. The faults have been subjected to microtectonic and petrophysical analysis. Small but significant changes occur in the porous network of the argillaceous matrix approaching a fault or shear zone, indicating compactional strain in both footwall and hanging wall. Internal compaction associated with faulting is put forward as a ductile–brittle feedback mechanism in the kinematics of intraformational fracture systems. Small differential stress induced by compaction and minor regional tectonic forces (differential uplift and tilt) and subsequent gravitational forces (downslope shear stress) induce small shear bands in nearly critically stressed weak mud. Shear banding is accompanied by layer-parallel shortening and bulk volume loss. This provides an additional extension of endogenous origin, accommodated by further deformation. This ductile–brittle feedback mechanism eventually leads to commonly observed intraformational collapse structures called polygonal fault systems.


Keywords: intraformational structures, soft-sediment deformation, argillite, strain, polygonal structures.




This article has been cited by other articles:


Home page
 Journal of the Geological SocietyHome page
J. Cartwright
The impact of 3D seismic data on the understanding of compaction, fluid flow and diagenesis in sedimentary basins
Journal of the Geological Society, 2007; 164: 881 - 893.
[Abstract] [Full Text] [PDF]