SURFICIAL SEDIMENTOLOGY OF THE MIDDELKERKE BANK (SOUTHERN NORTH-SEA)

Detailed surficial investigations over the Middelkerke Bank, a tidal s and bank in the southern North Sea, revealed the relationship between morphology, surficial structures and grain-size parameters. Data from 85 grab samples all over the bank show that on a bank normal profile, the coarser, CaCO3 rich and badly sorted sediments are generally locat ed near the highest point of the bank, seaward at the northern end and landward at the southern end. Sedimentary structures were studied fro m 239 boxcores sampled on all the morphological units of the bank: cre st, flanks and adjacent channels. In the shallower parts, foreset beds are preserved while in the deeper zones, intense bioturbation arises and destroys any structure. The combination between these data and the virtual absence of wave-induced structures indicates that the main ag ents responsible for the bank shaping are the tidal currents.