Late Carboniferous stratigraphy and sedimentology of the Bradford area, and its implications for the regional geology of northern England

Abstract

SUMMARY This paper presents descriptions and sedimentological interpretations of a number of sections in the Millstone Grit and Lower Coal Measures of the Bradford area, West Yorkshire. These are used to discuss the application of sequence stratigraphic models to cyclicity, particularly illustrating the problems of interpreting an erosive surface at the base of the Pule Hill Grit (Marsdenian R 2 ). A change in basin bathymetry is confirmed as the cause of an evolution of delta geometry from deep basin, turbidite-fronted deltas in the Kinderscoutian (R 1c 4), to shallow marine, sheet-like deltas from late Kinderscoutian to Yeadonian, and increasingly lacustrine environments during Langsettian times. Evidence is provided for switching of sediment supply in the Langsettian between the Elland, Greenmoor and Grenoside cycles. The importance of intrabasinal sedimentary controls on deposition is discussed in relation to the Elland and Greenmoor cycles. The importance of intrabasinal tectonics is highlighted by slumps in the Stanningley Rock, synsedimentary faults in the Rough Rock Flags and vertical stacking of channel sandstones in the Elland Flags. Displacements on the Denholme Clough and Aire Valley fault systems during early Marsdenian times apparently produced an area of raised sea-bed topography associated with condensed mudstone-successions, diversion of sandy deltaic lobes, lateral transition of the ammonoid-bearing Bilinguites bilinguis Marine Bands into Lingula bands and the shallow marine Keighley Bluestone.