Volcanic and Erosive Events on an Upper Viséan Carbonate Platform, North Derbyshire

SUMMARY Re-examination of erosive, sedimentary and volcanic phenomena within D zone (Upper Viséan) limestones of the Millers Dale area, North Derbyshire, has prompted the modification of previous suggestions on the sequence of events around the D 1 /D 2 boundary. Major erosive features hither to regarded as channels are attributed to karstic solution, indicating lengthy subaerial exposure of at least the northern part of the Derbyshire carbonate platform at the end of D 1 . Minor tectonic activity seems to have culminated in early D 2 times with the development of an unconformity and further karstic erosion which confined the lowest D 2 minor cycle (the Station Quarry Beds) to an incipient syncline in the region of Millers Dale. The ensuing Upper Millers Dale Lava was extruded across this early D 2 erosive surface as a succession of subaerial rather than submarine flows as previously thought, but its final extension at the eastern end of Millers Dale may have been in the form of a flow-foot breccia after an interval of partial inundation of the lava and local sedimentation. Stratigraphical similarity between Millers Dale and the platform margin to the north suggests a correlation between the Station Quarry Beds and the isolated P 1a incursion at the base of D 2 in Pindale.