Holocene peat deposits in the German Bight, southern North Sea – extending the reconstruction of the postglacial transgression seaward

Abstract

A set of 125 vibrocores collected on the basis of a dense grid of high and very high resolution seismic coverage over a tidal sand bank (the Middelkerke Bank) provides a unique opportunity to reconstruct the stratigraphy and sedimentary facies succession of such a large tidal sand body. Five sedimentary facies are distinguished. They range from clay to pebble and display various types of bedding and lithologies corresponding to different depositional environments. A succession of four Late Quaternary units are defined on the basis of the stratigraphic framework given by the seismic grid. The first unit represents the infill of a palaeovalley system by tidally influenced sedimentary facies. It is followed by extensive and thick lagoonal or sub-tidal deposits. The third unit reveals the development of a landward prograding storm-dominated sand bar. This unit is dominated by clean fine sand. The last unit corresponds to the present-day tidal sand-bank. It shows the typical offshore tidal sand bank facies (cross-bedded sand) prograding in an offshore direction. Like other banks located in a more offshore position, the Middelkerke Bank is a composite bank incorporating facies which do not occur in `classic' tidal sand banks.