A revised stratigraphical framework for the Quaternary deposits of the German North Sea sector: a geological‐geotechnical approach

Abstract

Using extensive data sets from three separate areas in the German North Sea sector, consisting of seismic grids, cores and in‐situ cone penetration tests (CPT), we have established a revised stratigraphical framework for the mid to late Quaternary deposits of the German North Sea sector. This framework consists of four regional unconformities and 15 other local unconformities derived from seismic profiles. Using these unconformities, along with lithological and geotechnical data, it was possible to define and correlate 14 major units and 21 subunits within the framework. The Quaternary cover in the area is characterized by a variety of environmental settings ranging from glacial terrestrial and fluvial to lacustrine as well as brackish and marine environments with associated erosion, reworking and deposition. The complexity of Quaternary deposits within the area is explained by its history of repeated ice advances interrupted by marine transgressions and exposed periglacial landscapes. Within the framework, eight buried tunnel valleys and two shallow buried river valleys are identified from seismic profiles with four phases of tunnel valley generation inferred. These phases of tunnel valley generation are associated with the Elsterian (three) and Saalian (one) glacial stages. Infill of these tunnel valleys consists of glaciofluvial sands, thick sequences of marine and lacustrine fine‐grained sediments and some reworked till remnants. Elsewhere, extensive tabular units have formed consisting of marine and fluvial sediments. We compare this new stratigraphy with previous stratigraphies for the German North Sea sector, attribute informal stratigraphical names and offer preliminary correlations with established stratigraphies from other sectors of the North Sea.

How a river submerges into the sea: a geological record of changing a fluvial to a marine paleoenvironment during early Holocene sea level rise

“…For the reworked sands Units IV to VI we can provide only apparent depositional rates; (h) stratigraphic interpretation of the lithological Units I–VI (red) (see text). The stratigraphical formation names are provided by Coughlan et al (). [Color figure can be viewed at wileyonlinelibrary.com]…”

Ice sheet and palaeoclimate controls on drainage network evolution: an example from Dogger Bank, North Sea

“…Previous explorations of submerged landscapes have used low-resolution 2D or 3D seismic reflection surveys designed to target deeper oil and gas reservoirs (Fitch et al, 2005;Gaffney et al, 2007Gaffney et al, , 2009 or combine oil and gas datasets with sparse high-resolution 2D seismic reflection data (Coughlan et al, 2018;Hepp et al, 2017Hepp et al, , 2019Prins and Andresen, 2019). Whilst this enables drainage networks to be identified, there is little information to constrain sedimentary and geomorphic processes and therefore the controls on landscape evolution.…”

“…The evolution of the terrestrial landscape of Dogger Bank over 10 kyr timescales, during a period of marked climate and far-field base-level change, has mainly focused on glacial (Cotterill et al, 2017b;Emery et al, 2019a;Phillips et al, 2018) and coastal stratigraphy (Emery et al, 2019a). Prins and Andresen (2019) established a transition from subglacial channel to terrestrial drainage in a study area 150 km northeast of Dogger Bank, but detail of the terrestrial landscape evolution at Dogger Bank during and after ice-sheet retreat has yet to be established.…”

Correction of water column height variation on 2D grid high-resolution seismic data using dGPS based methodology

“…The oldest sediment belongs to a large tunnel valley defined by Unit 1. Comparable tunnel valley in the area described by Hepp 15 , Lutz 28 and Coughlan 17 suggest that this unit is made up of glacio-fluvial sand deposited in the Pleistocene. This was followed by the infill Unit 2 defined by Reflectors R2_1 and R2_2.…”

“…Wetland systems consisting of tidal channels and coastal salt marshes among other structures constitutes other known features within the study area 21 , 22 . A detailed stratigraphic framework of the Quaternary deposit of the German sector of the North Sea is summarized in Coughlan 17 .…”