Hostname: page-component-848d4c4894-tn8tq Total loading time: 0 Render date: 2024-07-05T02:09:10.706Z Has data issue: false hasContentIssue false
  • English
  • Français

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.
Get access Rights & Permissions [Opens in a new window]

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

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

British Geological Survey. in press. Cadair Idris. I: 50,000 Sheet 149.Google Scholar
Cox, A. H. 1925. The geology of the Cader Idris range (Merioneth). Quarterly Journal of the Geological Society, London 81, 539–92.CrossRefGoogle Scholar
Donath, F. A. 1968 a. Experimental study of kink band development in Martinsburg slate. In Research in Tectonics (eds Baer, A. J. and Norris, D. K.), pp. 255–88. Geological Survey of Canada Paper 68–52.Google Scholar
Donath, F. A. 1968 b. The development of kink bands in brittle anisotropic rock. In Igneous and Metamorphic Geology (ed. Larsen, L. H.), pp. 95–128. Memoir of the Geological Society of America 135.Google Scholar
Durney, D. W. & Ramsay, J. G. 1973. Incremental strains measured by syntectonic crystal growths. In Gravity and Tectonics, (eds De Jong, K. A. and Scholten, R.), pp. 67–96. New York: Wiley.Google Scholar
Fitches, W. R. & Campbell, S. D. G. 1987. Tectonic evolution of the Bala Lineament in the Welsh Basin. Geological Journal 22, 131–53.CrossRefGoogle Scholar
Gay, N. C. & Weiss, L. E. 1974. The relationship between principal stress directions and the geometry of kinks in foliated rocks. Tectonophysics 21, 287–300.CrossRefGoogle Scholar
Jehu, R. M. 1926. The geology of the district around Towyn and Abergynolwyn (Merioneth). Quarterly Journal of the Geological Society of London 82, 465–89.CrossRefGoogle Scholar
Kleist, J. R. 1972. Kink bands along the Denali Fault, Bulletin of the Geological Society of America 83, 3487–90.CrossRefGoogle Scholar
Kokelaar, P. 1988. Tectonic controls of Ordovician arc and marginal basin volcanism in Wales. Journal of the Geological Society, London 145, 759–75.CrossRefGoogle Scholar
Kusky, T. M., Kidd, W. S. F. & Bradley, D. C. 1987. Displacement history of the Northern Arm Fault and its bearing on the post-Taconic evolution of north-central Newfoundland. Journal of Geodynamics 7, 105–33.CrossRefGoogle Scholar
Martin, B. A., Howells, M. F. & Reedman, A. J. 1981. A geological reconnaissance study of the Dyfi Valley region, Glvynedd/Powys, Wales. Environmental Protection Unit (ENPU 81–1), Institute of Geological Sciences.Google Scholar
Owen, T. R. 1974. The Variscan orogeny in Wales. In The Precambrian and Lower Palaeozoic rocks of Wales, (ed. Wood, A.), pp. 28–94. Cardiff: University of Wales Press.Google Scholar
Paterson, M. S. & Weiss, L. E. 1966. Experimental deformation and folding in phyllite. Bulletin of the Geological Society of America 77, 343–74.CrossRefGoogle Scholar
Ramsay, A. C. 1881. Geology of North Wales. Memoir of the British Geological Survey 3, 2nd ed.Google Scholar
Ramsay, J. G. & Huber, M. I. 1987. The Techniques of Modern Structural Geology, vol. 2. London: Academic Press.Google Scholar
Thomas, T. M. 1970. The imprint of structural grain on the micro-relief of the Welsh Uplands. Geological Journal 7, 69–100.CrossRefGoogle Scholar
Weiss, L. E. 1968. Flexural slip folding of foliated model materials. In Research in Tectonics (eds Baer, A. J. and Norris, D. K.), pp. 294–357. Geological Survey of Canada Paper 68–52.Google Scholar
Wilson, D., Davies, J. R., Smith, M. & Waters, R. A. 1988. Structural controls on Upper Palaeozoic sedimentation in south-east Wales. Journal of the Geological Society, London 145, 901–14.CrossRefGoogle Scholar