Abstract

The Shale Grit and Grindslow shales (which together make up the Alport group) lie between the Mam Tor sandstones (turbidites) and the Kinderscout grit (near-shore or coastal plain). All these formations are of Namurian (upper Carboniferous) age and crop out in the north Derbyshire part of the central Pennine basin, England. The Shale Grit contains two main sandstone facies, 1, alternating parallel sided sandstones and mudstones interpreted as distal turbidites and 2, thick sandstones without mudstone partings interpreted as very near source, proximal turbidites. There are also three mudstone facies, silty mudstones, pebbly mudstones and thinly laminated black mudstones. The Grindslow shales contain both of the Shale Grit sandstone facies, together with sandy mudstones, burrowed silty mudstones, parallel bedded silty sandstones and carbonaceous sandstones. The sequence from the Mam Tor sandstones (distal turbidites) via the lower Shale Grit (distal, with subordinate proximal turbidites) into the upper Shale Grit (proximal, with subordinate distal turbidites) suggests advance of a submarine fan southward into the north Derbyshire area. This southward advance of facies belts continued as the Grindslow shales 'slope' environment covered the fan, and was itself covered by the near-shore or coastal plain Kinderscout grit.

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