Abstract

In Late Silurian-Early Devonian time a major uplift in Scandinavia-Greenland may have provided sediment for sinistral strike-slip basins in Scotland, alluvial coastal plains in Wales and may have sourced the thick marine clastics with ORS tongues in southern Britain and the Ardennes. By the Middle Devonian, lacustrine ORS in the Orcadian basin, non-sequences in central and south Scotland and Wales, carbonates in Devon and argillites in Cornwall indicate the end of the early paroxysmic erosional cycle. In Wales and the Bristol Channel region there is evidence of more local tectonism, with episodes of coarse clastic sedimentation. Basal volcanics show intra-plate rather than oceanic affinities. Evidence of marine transgressions, culminating in the Frasnian, is present in Southwest England and in the subsurface of East Anglia, as in the Ardennes, and marine carbonate facies reached well north in the North Sea in the Middle Devonian. Late tectonism is recognized in Scotland and there was a renewal of clastic sedimentation around the Bristol Channel area. Famennian regressional facies are indicated. In Cornwall progressive obduction from the south, suggested by the Lizard ophiolite complex, gave melange deposits and turbidites to more northerly basins: this culminated in olistostromes and gravity faults in the Early Carboniferous, thus modifying the old view that the complex tectonics of the south resulted solely from a Late Carboniferous Armorican Orogeny.