Slump folds and gravity slide structures in a Lower Palaeozoic marginal basin sequence (the Skiddaw group), NW England

Abstract

Major folds with associated thrust faults and a major olistostrome are described from the Skiddaw Group, a Lower Ordovician turbidite sequence in the Lake District of NW England. The style and geometry of the structures are shown to be compatible with their generation as submarine slumps or slide masses although they are much larger than any slump structures hitherto described from Britain. The predominant strain is shown to be simple shear. Spatial and temporal variations in strain permit a developmental model to be erected. The opposing vergence of the structures across the mapped area indicates a relatively narrow, probably fault controlled, depositional basin.