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The use of kink bands to constrain fault displacements: an example from the Bala Lineament, Wales

Published online by Cambridge University Press:  01 May 2009

W. T. Pratt
W. T. Pratt
Affiliation:
British Geological Survey, Bryn Eithyn Hall, Llanfarian, Aberystwyth, Dyfed SY23 4BY, U.K.
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Abstract

The Bala Lineament is a major NE-SW-striking fault zone that crosses the Lower Palaeozoic Welsh Basin. The southwest segment of it, the Tal-y-llyn Fault, mostly lies within a tract of Ordovician mudstones with few marker bands. Consequently, post-Caledonian (early Devonian) displacements are poorly understood. However, there is a close link between the distribution of kink bands and the fault zone. The kink bands provide information about the contemporary stress conditions and, in combination with slickensided fractures, give qualitative information about the various fault displacements. Matching of major folds across the fault suggests approximately 3–4 km of dextral strike-slip, probably of Lower Carboniferous age. A younger episode of normal faulting, perhaps related to Mesozoic extension, was accompanied by kink bands with more brittle characteristics.

Type
Articles
Information
Geological Magazine , Volume 129 , Issue 5 , September 1992 , pp. 625 - 632
Copyright
Copyright © Cambridge University Press 1992

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