ELSEVIER Tectonophysics 309 (1999) 27–39 www.elsevier.com/locate/tecto A new Variscan deformation map of England and Wales Richard J. Lisle * Laboratory of Strain Analysis, Department of Earth Sciences, Cardiff University, Main College, Park Place, Cardiff, Wales CF1 3YE, UK Accepted 6 April 1999 Abstract Collections of bedding orientations from subareas of 550 km 2 are used to define bedding fabrics from the Variscan fold belt and foreland in England and Wales. The bedding fabrics, constructed from data taken from published geological maps (1 : 50,000 scale), are analysed in terms of the Scheidegger–Watson orientation tensor. The calculated eigenvalues of the orientation tensor define the average structural trends, including the best-fit fold axis, for each subarea, The eigenvectors of the tensor allow the original sedimentary fabrics to be distinguished from those modified by deformation. The progressive tectonic modification of these fabrics leads to the concept of fabric evolution paths, and the extent of the modification is expressed by a deformation parameter. Although it is emphasised that this parameter is not solely a function of finite strain magnitude, its variation is represented on a map which brings out different degrees of Variscan tectonic modification of bedding fabrics. This map delineates a Variscan bedding fabric front corresponding to the northern boundary of a zone of pervasive and strong deformation. In the foreland this new analysis allows the variation of Variscan trends to be mapped, and the significance of these trends to be quantified in terms of deformation magnitude.  1999 Elsevier Science B.V. All rights reserved. Keywords: statistical analysis; deformation; Variscan; bedding fabric 1. Introduction Previous regional surveys of Variscan deforma- tion in the British area have resulted in maps show- ing the trends of important folds and faults (e.g. Dunning, 1966). Ideally, surveys of this kind would also include a quantitative assessment of the inten- sity of deformation as well as the principal direc- tions of strain. Although strain analyses have been undertaken for small regions, e.g. southwest Eng- land (Sanderson and Dearman, 1973), south Wales (Hanna and Fry, 1979; Hanna and Graham, 1988), Ł Fax: C44-1222-874326; E-mail: lisle@cardiff.ac.uk the extension of such studies to a regional scale is hindered by the lack of availability of strain markers. Furthermore, such studies would be time-consuming and produce results that could reflect local strain variations as well as regional strain patterns. This paper presents a new method for assessing regional deformation in a semi-quantitative manner, using the most ubiquitous of strain markers, the assemblages of bedding plane orientations in sedi- mentary rocks. The method is presented here as a generic technique with potential application to other orogenic belts. The use of the method is illustrated by applying it to analyse the deformation of the Variscan foreland of England and Wales. 0040-1951/99/$ – see front matter  1999 Elsevier Science B.V. All rights reserved. PII:S0040-1951(99)00130-4