The Apedale tuffs, North Staffordshire: probable remnants of a late Asbian/Brigantian (P1a) volcanic centre

Abstract

A borehole sunk in 1920–21 at Apedale, North Staffordshire, unexpectedly proved a tuff-dominated sequence, at least 840m thick, below a thin cover of Silesian sedimentary rocks. The tuffs were initially interpreted as Dinantian in age. However, there are similarities of form and lineament between an aeromagnetic anomaly centred upon Apedale and anomalies in the Welsh Marches associated with Neoproterozoic (Uriconian) rocks, suggesting that Neoproterozoic rocks occur at Apedale and that the tuffs in Apedale Borehole might also be of this age. Recent modelling of geophysical data shows that Apedale is underlain by two (magnetic) volcanic bodies — a deeper ridge of probable Uriconian rock, and a shallower, broadly stratiform body which includes the tuffs in the Apedale Borehole. Comparison of the tuffs at Apedale with others in the region suggests that they are of P1a (late Asbian to early Brigantian) age. Although our knowledge of the extent of the Apedale tuffs is poor, their thickness shows that they erupted from one of the largest centres of Dinantian volcanism in central England. The trace element geochemistry is very similar to that of Dinantian volcanic rocks in southwest England.

Windsor Group (Late Mississippian) stratigraphy, Magdalen Islands, Quebec: a rare eastern Canadian record of late Visean basaltic volcanism

“…The presence of Asbian K-bentonitic clay horizons in North Wales was reported by Somerville (1979). Rees et al (1996) described Asbian basaltic tuffs in a deep borehole at Apedale in central England and linked this volcanic activity to much more widespread volcanism. They attributed this volcanism to active late Asbian and early Brigantian rifting which affected much of northwestern Europe.…”