Published:January 01, 2011
E. C. Freshney, B. E. Leveridge, R. A. Waters, C. N. Waters, 2011. "Culm Basin", A Revised Correlation of Carboniferous Rocks in the British Isles, C. N. Waters, I. D. Somerville, N. S. Jones, C. J. Cleal, J. D. Collinson, R. A. Waters, B. M. Besly, M. T. Dean, M. H. Stephenson, J. R. Davies, E. C. Freshney, D. I. Jackson, W. I. Mitchell, J. H. Powell, W. J. Barclay, M. A. E. Browne, B. E. Leveridge, S. L. Long, D. McLean
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To the south of the Mississippian platform carbonate successions of South Wales (Chapter 5) and Bristol, Mendips and Somerset (Chapter 6), Carboniferous rocks predominantly occur within the strongly deformed Culm crop of SW England. The Culm Basin has a broad graben architecture, with an inner graben (Central Devon Sub-basin) fianked by half-grabens (Bideford and Launceston sub-basins) (Fig. 14; Leveridge & Hartley 2006; Waters et al. 2009). The Bideford Sub-basin is bounded to the north by the Brushford Fault, the Central Devon Sub-basin by the Greencliff Fault and the Launceston Sub-basin by the Rusey Fault. To the north of the Brush-ford Fault is the northern margin of the Culm Basin. The Tavy Basin has limited development of Famennian-Tournaisian strata. The Laneast High separating the Tavy Basin and Launceston Sub-basin includes a Tournaisian to ?Visean succession (Yeolmbridge and Laneast Quartzite formations). Remnants of Carboniferous strata also occur in the South Devon Basin.
In many areas there is no clear lithological break between the Tournaisian and the underlying Upper Devonian rocks, both of which are dominated by shallow-marine and deeper-water mudstones. The succession, commonly referred to as the Transition Series or Group (Dearman & Butcher 1959; Freshney et al. 1972), are assigned to the Exmoor Group in north Devon, the Hyner Mudstone and Trusham Mudstone formations of the eastern part of the Central Devon Sub-basin and the Tamar Group in south Devon.
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A Revised Correlation of Carboniferous Rocks in the British Isles
The report revises and expands upon the 1976 and 1978 publications for the Dinantian and Silesian, respectively, combining them into a single account of British and Irish Carboniferous stratigraphy. The need to update the two Special Reports reflects the considerable advances in Carboniferous geology over the last 30 years. The report covers developments in international chronostratigraphy and incorporates wholesale reassessments of British lithostratigraphy. A huge volume of biostratigraphical information has been published over recent decades and the report summarizes the key information.
Carboniferous rocks have long been of economic importance, but it is the search for hydrocarbons, in its infancy at the time of the previous reports, which has greatly increased our understanding of Carboniferous successions offshore and at depth, particularly in southern and eastern England.