Palaeogeography and facies evolution
Published:January 01, 2003
Having discussed the broad-scale tectono-stratigraphic subdivision of the north of England Carboniferous in the previous section, we now use the megasequences and tectono-stratigraphic sequences to determine the spatial and temporal evolution of depositional systems using sequence palaeogeo- graphies.
By late Devonian times, rifting had begun in northern England with sedimentation occurring in incipient half graben under an arid climate. The remnant Caledonian mountain belt to the north acted as a major sediment source (e.g. Gilligan 1920; Leeder 1988; Gawthorpe et al. 1989) and, in the study area, Caledonian structures were reactivated and also acted as local sediment sources.
The northward drift of European Pangaea during the Dinantian led to a change to humid climatic conditions by the late Dinantian (Duff, 1980). This, together with regional transgression, caused a change from red-bed style deposition to fluvio-deltaic deposition in the north of the area, close to the major sediment source, and predominantly carbonate depositional systems in the south of the area, particularly on footwall highs starved of clastic sediment. The development of high-frequency cyclicity in late Dinantian times (e.g. Walkden 1987; Leeder & Strudwick 1987) signifies the growing importance of glacio-eustasy as a control on stratigraphic development; a control which became dominant in the Silesian.
There is general agreement that northern Britain occupied an equatorial position during the Namurian (Scotese et al. 1979; Smith et al. 1981), and the occurrence of coal and bauxitic soil horizons in Scotland indicates a humid, tropical
Figures & Tables
An Atlas of Carboniferous Basin Evolution in Northern England
Why an atlas of the Carboniferous in northern England? There can hardly be a more researched system in the whole of the British Isles, given its widespread distribution at outcrop and annual appearances in numerous PhD theses (including those of the authors). But perhaps all we really know about the Carboniferous is no more than skimming the surface. In this atlas, using modern multifold seismic and borehole data collected by the oil industry in its search for petroleum accumulations, we can start to look beyond the surface exposures and gain some new insights into the structure and stratigraphy of the subsurface (and surface) Carboniferous.
The unique appeal of this atlas of seismic sections is that it is based on data from onshore UK. Although these lines were originally shot as small segments targeting individual prospects and trends, they have been spliced together to produce a series of basin-scale regional lines which should be of value to academic researchers and industry alike. With this atlas, we can walk the seismic lines at outcrop and in many cases compare exposure to both the seismic data and associated palaeofacies maps.