Sand body orientation, palaeoslope analysis and basin-fill implications in the Westphalian A–C of Great Britain

Abstract

Channel orientation and palaeoflow analyses across the British Westphalian (Carboniferous) coalfields show that three main inflow directions dominated the palaeogeography from the mid-Langsettian to the mid-Bolsovian. In eastern Scotland and NE England, flow was mainly from the N and NE. In the Pennine Basin of north central England, flow was mainly from the W and NW, whilst in South Wales, main flow from the SW was compatible with a westerly system that also branched to give the northerly inflows recorded in the Culm Basin of southwest England. The depositional area included discrete tectonic depocentres, notably the Pennine Basin, which was traversed directly and tangentially by major channel belts. These basins were essentially incidental to the main channel pathways, but sand body characteristics vary according to basin location. A new depositional model for the post-rift Pennine Basin is proposed, relating sand concentrations and connectivities to the depositional and tectonic setting. The description of dominant SW to NE flow across South Wales through much of the Langsettian and Duckmantian, in contrast to the centripetal inflows previously proposed, implies some similar channel/depocentre relationships to those described here for the Pennine Basin.

The Western Irish Namurian Basin reassessed

“…However, a thick succession of younger Carboniferous sediments occurs in the basins of northern England and they display an intriguing change in sediment provenance in the immediate post-Namurian interval. Much of the Namurian in®ll of the region was derived from terranes to the north-east, but in the Westphalian the principal sediment supply switched to the west (Rippon, 1996). The Sr±Nd signature of the new source material suggests a young crustal source probably associated with a developing orogenic front (Glover et al, 1996).…”

Provenance of late Carboniferous sandstones in the Pennine Basin (UK) from combined heavy mineral, garnet geochemistry and palaeocurrent studies

“…There are a number of ultramafic rocks to the west that are potential sources of the chrome spinel bearing detritus. Small local sources, such as the Mona Complex of Anglesey, are considered unlikely to have been the main suppliers of chrome spinel because of the large size and scale of the Westphalian river systems involved (Rippon, 1996). Furthermore, zircon age data rule out significant contributions from the Mona Complex, since the westerly derived detritus lacks late Precambrian to early Cambrian zircons that would be associated with derivation from this complex .…”

Geological controls on the sulphur content of coal seams in the Northumberland Coalfield, Northeast England

“…In the UK, Westphalian Coal Measures cleat formation is thought to be primarily controlled by tectonism following uplift and release of overburden pressure (Rippon, 1996). Thus, pyrite-coating cleat surfaces post-dates cleat formation and coalification.…”