Late Weichselian to early Holocene subaqueous dune formation and burial off the North Sea Northumberland coast

Abstract

High resolution seismic profiles from the North Sea, 20 km off Northumberland, have shown the presence of a 25 km 2 subaqueous dune field buried beneath Holocene marine mud. The dunes are composed of fine to medium sand with occasional pebbles and have heights ranging from 0.5 m to 5.5 m and spacings from 100 m to 600 m. Most larger dunes (> 2 m high) have their steeper slopes facing to the south and internal reflectors representing foreset bedding that dips to the south, suggesting dominant southward sand transport. The dunes are inferred to have been produced by tidal currents of between 1.00 and 1.50 m/s in a shallow water tidal embayment or large estuary during the initial stages of the post-glacial marine transgression in the area, sometime between about 10,700 and 9700 yr B.P. Burial of the dunes occurred when the dimensions of the tidal embayment were increased, tidal current velocities reduced beneath the threshold for dune formation and finer-grained sediment was deposited. The tops of the dunes were eroded and a deflation surface formed before burial.