A lithostratigraphical framework for the Carboniferous successions of northern Great Britain (onshore)

The Stratigraphy Committee of the British Geological Survey (BGS) is undertaking a review of stratigraphical classification for all parts of Great Britain. Several Stratigraphical Framework Committees (SFC) have been established to review problematical issues for various parts of the stratigraphical column. Each SFC has the following terms of reference: • to review the lithostratigraphical nomenclature of designated stratigraphical successions for a given region, identifying problems in classification and correlation • to propose a lithostratigraphical framework down to formation level • to organise peer review of the scheme • to present the results in a document suitable for publication • to ensure that full definitions of the lithostratigraphical units are held in the web-accessible BGS Lexicon of Named Rock Units for the areas of responsibility covered by the SFC. The economic importance of strata of Carboniferous age has resulted in over 200 years of research attempting to classify them. Much of this work occurred long before guidance was available for best practice in naming lithostratigraphical units. Consequently, a haphazard approach to the establishment of the hierarchy of units has resulted. From an early, relatively simple framework, subsequent surveys and publications have greatly added to the complexity of the nomenclature. Often, this reflected the localised nature of research with a tendency to identify numerous local names for essentially the same unit. Also, end Carboniferous and subsequent tectonic events have resulted in the isolation by faulting or erosion of laterally contiguous deposits often resulting in a plethora of local names. This complexity in nomenclature has, to an extent, hindered the regional understanding of the Carboniferous successions throughout Great Britain. Two committees have reported on the Carboniferous succession of the Midland Valley of Scotland (Browne et al., 1999) and the Westphalian to early Permian red-bed successions of the Pennine Basin (Powell et al., 2000) respectively. Further committees were established to review the Carboniferous successions of the Scottish Borders and the Namurian successions of the Pennine Basin. In 2000, these committees were subsumed into a single committee, which reviewed the entire Carboniferous successions throughout Great Britain. This report summarises the SFC lithostratigraphical scheme for onshore Carboniferous successions of northern Great Britain. A further report summarises the scheme employed in southern Great Britain (see Waters et al., 2009). The first part of this report summarises the structural and palaeogeographical setting of northern Great Britain throughout the Carboniferous Period. The second part describes the key techniques of correlation of successions, principally biostratigraphy. The third part indicates the principle for the development of the new lithostratigraphical scheme. This demonstrates how the group hierarchy has been linked to major lithofacies and the procedures for rationalising existing nomenclature. The fourth and largest part of the report provides a full description of the group and formation framework for each of three regions; Scotland north of the Southern Upland Fault, southern Scotland, and the Northern England Province (including the Isle of Man). Each entry includes the rank of the nomenclature, and a description of its origin and history and key references, principal lithologies, environment of deposition, stratotypes, lower and upper boundaries, thickness, geographical extent, age range and any subdivisions to member level. The members themselves are similarly fully described. An appendix (Appendix 1) provides an alphabetical listing of each supergroup, group, formation and member respectively, and shows the heirarchical relationship between the lithostratigraphical units. It also provides computer codes from the BGS Lexicon of Named Rock Units where these have been allocated. Appendix 2 gives the BGS Lexicon of Named Rock Units computer codes for the lithostratigraphical beds shown in Figures 6 and 8–15 and Appendix 3 lists all the obsolete lithostratigraphical terms mentioned in the text and provides the units they are now equivalent to or included within.