TY  - JOUR
A1  - Wenau, Stefan
A1  - Alves, Tiago M.
T1  - Salt-induced crestal faults control the formation of Quaternary tunnel valleys in the southern North Sea
Y1  - 2020
VL  - 49
IS  - 4
SP  - 799
EP  - 812
JF  - Boreas
DO  - 10.1111/bor.12461
DO  - 10.23689/fidgeo-4866
N2  - Tunnel valleys are major features of glaciated margins and they enable meltwater expulsion from underneath a thick ice cover. Their formation is related to the erosion of subglacial sediments by overpressured meltwater and direct glacial erosion. Yet, the impact of pre-existing structures on their formation and morphology remains poorly known. High-quality 3D seismic data allowed the mapping of a large tunnel valley that eroded underlying preglacial delta deposits in the southern North Sea. The valley follows the N–S strike of crestal faults related to a Zechstein salt wall. A change in downstream tunnel valley orientation towards the SE accompanies a change in the strike direction of salt-induced faults. Fault offsets indicate important activity of crestal faults during the deposition of preglacial deltaic sediments. We propose that crestal faults facilitated tunnel valley erosion by acting as high-permeability pathways and allowing subglacial meltwater to reach low-permeability sediments in the underlying Neogene deltaic sequences, ultimately resulting in meltwater overpressure build-up and tunnel valley excavation. Active faults probably also weakened the near-surface sediment to allow a more efficient erosion of the glacial substrate. This control of substrate structures on tunnel valley morphology is considered as a primary factor in subglacial drainage pattern development in the study area.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9212
ER  -