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Keywords:

  • tunnel valley;
  • channel infill;
  • seismic data;
  • cone penetration tests;
  • core description

Abstract

A combination of a dense reflection seismic grid and up to 50-m-long records from sediment cores and cone penetration tests was used to study the geometry and infill lithology of an E–W-trending buried tunnel valley in the south-eastern North Sea. In relation to previously known primarily N–S-trending tunnel valleys in this area, the geometry and infill of this 38-km-long and up to 3-km-wide valley is comparable, but its E–W orientation is exceptional. The vertical cross-section geometry may result from subglacial sediment erosion of advancing ice streams and secondary incision by large episodic meltwater discharges with high flow rates. The infill is composed of meltwater sands and reworked till remnants on the valley flanks that are overlain by late Elsterian rhythmic, laminated, lacustrine fine-grained sediments towards the centre of the valley. A depression in the valley centre is filled with sediments most likely from the Holsteinian transgression and a subsequent post-Holsteinian lacustrine quiet-water setting. The exceptional axis orientation of this tunnel valley points to a regional N–S-oriented ice front during the late Elsterian. Copyright © 2012 John Wiley & Sons, Ltd.