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Exploration and Evaluation Techniques |
Department of Earth Sciences, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK
During the late Carboniferous, the Pennine Basin, UK was a thermally subsiding, intracratonic basin with little active tectonism. The sedimentary fill of the basin consists of coarsening-upward coal-bearing deltaic cyclothems bounded by widespread faunalconcentrate condensed horizons. The Yeadonian (Namurian G1) Rough Rock Group comprises three such cyclothems that have been studied at outcrop and in core using detailed sedimentological logging and then applying high resolution sequence stratigraphical concepts. Key surfaces and systems tracts are recognized and a sequence stratigraphic framework is constructed using these criteria and incorporating basin biostratigraphy and palaeogeography.
Two regionally extensive coals are present in the Rough Rock Group. They formed under relatively long-lived, basin-wide conditions of (1) clastic sediment starvation and (2) rising water-table, creating accommodation space for peats to accumulate and be preserved in mires. These conditions are characteristic of deposition in transgressive systems tracts and in the context of the Rough Rock group sequence stratigraphic framework these coals are identified as up-dip equivalents of initial flooding surfaces. This example raises wider implications for the discrimination of other regionally extensive coals in the upper Carboniferous strata of the Pennine basin using high resolution sequence stratigraphic concepts.
