Page 20 - An Atlas of Carboniferous Basin Evolution in Northern England

Regional structural framework 11

around major normal fault zones that bound half graben depocentres. It is cyclicity is apparent in platform carbonates, especially towards the end of the been identified, suggesting extra-basinal controls on sediment source areas and
composed of six tectono-stratigraphic sequences (EC1-EC6) (Fig. 8). Two Dinantian in the Asbian and Brigantian stages (Walkden 1987; Horbury 1989). sediment transport pathways (e.g. Glover et al. 1996; Hallsworth & Chisholm
main syn-rift depositional systems can be identified: (i) clastic fluvio-deltaic and The post-rift megasequence ranges in age from late Brigantian to late 2000; Hallsworth et al 2000)
(ii) carbonate platforms (Fig. 9). The clastic depositional systems dominate the Westphalian C and was deposited regionally across northern England. The The inversion megasequence ranges in age from late Westphalian C to early
north of the study area (e.g. Northumberland Basin) due to the proximity to stratigraphy is dominated by fluvio-deltaic sandstones, siltstones, mudstones Permian. This megasequence records the development of a series of inversion
the eroding remnants of the Caledonian mountain belt situated to the north. In and coals, although initial deposition in the sediment-starved half graben in the anticlines and widespread uplift and erosion of the original syn-rift depocentres
contrast, the southern part of the study area (e.g. Widmerpool Gulf, south of the area is characterized by basinal mudstones and deepwater (e.g. Corfield et al. 1996). Associated with this uplift was a change in the
Gainsborough Trough and Bowland Basin) was largely starved of clastic turbidites. High-frequency cyclicity in the Namurian and Westphalian has been depositional style, with progressive development of red beds and coarse pebbly
sediment during syn-rift times. In addition, the equatorial location of northern long recognized (Bott & Johnson 1967; Ramsbottom 1973, 1977), and more sandstones and conglomerates from the inversion axes and from the south. The
England at that time allowed shallow-water areas to become the sites of prolific recently these cycles have been recognized to form high-frequency depositional inversion megasequence can locally be subdivided into two tectono-strati-
carbonate production and carbonate platform development, whereas the half- sequences and component systems tracts (e.g. Church & Gawthorpe 1994; graphic sequences; however, the lack of preserved stratigraphy due to
graben depocentres became sediment starved and were infilled by predomi- Wignall & Maynard 1996; Hampson 1997; Hampson et al 1997; Jones & progressive uplift and erosion precludes the development of a regional
nantly fine-grained hemipelagic deposits (Gawthorpe 1987a). High-frequency Chisholm 1997). In recent years major changes in provenance and source area framework.
compositions in the late Namurian and Westphalian of the Pennine Basin have