|
Department of Earth Sciences, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK
The Rough Rock Group (Upper Carboniferous, Namurian G1) of northern England comprises fluvio-deltaic strata exhibiting high frequency cyclicity. Key elements of high-frequency sequences are recognized in these strata, including lowstand braided fluvial incised valley fills and their correlative interfluve palaeosols. The geometry of these incised valley fills was controlled by the local, synsedimentary tectonic setting. Regionally-extensive coals overlie these incised valley fills and their interfluve palaeosols and are interpreted as initial flooding surface correlatives. These coals are in turn overlain by shales containing faunal-concentrate condensed horizons (marine bands) which are interpreted as maximum flooding surfaces. A previously unrecognized marine band which overlies the Sand Rock Mine Coal and underlies the Rough Rock Flags is documented, implying a major revision of the published stratigraphy and sequence stratigraphy. These sequence stratigraphic elements define four high frequency siliciclastic sequences, which are integrated into a sequence stratigraphic framework for the Rough Rock Group. This framework allows sequence architecture, palaeogeographies and stacking patterns to be described in detail and also provides a basis for identifying potential controls on these variables.
