The University of Southampton
University of Southampton Institutional Repository

Effects of layering and anisotropy on fault geometry

Peacock, D.C.P. and Sanderson, D.J. (1992) Effects of layering and anisotropy on fault geometry Journal of the Geological Society, 149, (5), pp. 793-802. (doi:10.1144/gsjgs.149.5.0793).

Record type: Article

Abstract

The geometry and orientation of faults are examined using several field examples of small-scale (< lm displacement) fault systems. For isotropic rocks under triaxial compression, faults normally develop in conjugate sets about the maximum compressive stress (1), with dihedral angles usually of about 50°, as predicted by the Coulomb theory of failure. In layered rocks, the geometry of faults varies with the orientation of layering with respect to the stress field. Where 1, is approximately normal to layering or anisotropy, conjugate faults also develop symmetrically about 1. Where rocks have interbedded layers with different mechanical behaviours, however, faults tend to initiate orthogonal to the more brittle layers (i.e. originate as extension fractures sub-parallel to 1), but oblique to the less brittle layers. As the fault steps through the layering, pull-aparts are developed which may reduce the dihedral angle. Where 1 is oblique (c. 25–75°) to anisotropy, one set of faults is developed at a high angle to layering, with another at a low angle, usually showing a ramp-flat geometry. Large dihedral angles (up to 90°) may result and 1, does not bisect this angle.

Where 1 is approximately parallel to layering, two cases can be recognized. Where 3 is approximately normal to layering, faults with layer-parallel flats and contractional ramps develop. Where 2 is approximately normal to layering, conjugate faults develop which are symmetrical about 1, the geometry resembling that in isotropic rocks. These observations are in agreement with rock deformation experiments which show the strong effect of anisotropy on fault orientation, but the observations incorporate the effects of layering of materials with different deformation characteristics.

Full text not available from this repository.

More information

Published date: October 1992

Identifiers

Local EPrints ID: 74705
URI: http://eprints.soton.ac.uk/id/eprint/74705
ISSN: 0016-7649
PURE UUID: 5d0c8a1c-6225-4494-92d0-bdc1132bf5c9
ORCID for D.J. Sanderson: ORCID iD orcid.org/0000-0002-2144-3527

Catalogue record

Date deposited: 11 Mar 2010
Last modified: 18 Jul 2017 23:45

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×