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Basement fractures in North Wales: their recognition and control on Caledonian deformation

Published online by Cambridge University Press:  01 May 2009

I. Wilkinson  and
M. Smith
I. Wilkinson
Affiliation:
Department of Geology, University College of Wales, Aberystwyth, Dyfed, SY23 3DB, Wales
M. Smith
Affiliation:
British Geological Survey (NERC), Bryn Eithyn Hall, Llanfarian, Aberystwyth, SY23 4BY
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Abstract

A detailed survey of the patterns of regional deformation in North Wales has revealed the presence of several discrete, linear zones of anomalous deformation. These zones are distinguished by atypical finite strain values, intense tight to isoclinal folding, non-axial planar cleavages and high metamorphic gradients. A history of prolonged tectonic activity along these zones is indicated by their influence on sedimentation and volcanism. It is proposed that these zones reflect the deformation of the Lower Palaeozoic cover above pre-existing basement fractures. These basement fractures form a framework which divides North Wales into a series of blocks and sub-blocks. The end-Caledonian deformation is explained by a transpression model dominated by SE-directed shear with minor components of strike-slip localized in these zones. The application of this model to other parts of the Welsh Basin is briefly considered.

Type
Articles
Information
Geological Magazine , Volume 125 , Issue 3 , May 1988 , pp. 301 - 306
Copyright
Copyright © Cambridge University Press 1988

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