Glacitectonics of the Dogger Bank Region

Abstract

Glacitectonics are found in all known glacial landscapes, but complex relationships exist at many scales between structures, landforms and processes. The deformation mechanisms forming glacitectonic complexes mainly occur at oscillating dynamic glacier margins. Understanding these processes offers insight of ice sheet dynamics through the influence of advance/retreat phases on sediment supply and deformation. However, understanding of the factors controlling sedimentation and deformation at former ice sheet margins is limited. A unique high-resolution seismic dataset, acquired for a large-scale windfarm development project is used to address the lack of understanding of the evolution of the Dogger Bank, the dynamics of the British-Irish Ice Sheet (BIIS) in the southern North Sea and potential interactions with the Fennoscandian Ice Sheet (FIS). This seismic dataset is used to characterise, describe and interpret detailed evidence of glacitectonic deformation in the Dogger Bank region. Traditional 2D interpretation of the high-resolution seismic data is compiled using a new 'domain' approach to offer insight into regional-scale glacitectonics. This data is integrated through a dense seismic survey network to generate a palaeo- land- surface map and a 3D model of deformation kinematics for the Dogger Bank region. This study identi fies a large moraine complex with wide-spread deformation up to a depth of approximately 40m below the present day sea-level, representing a LateWeichselian steady-state, oscillating ice sheet, with an active ice retreat from the north (FIS). This steady-state phase is followed by a signifi cant readvance event by the BIIS from the West, where deep deformation (up to 200m below the present-day sea level) at the western side of the Dogger Bank reflects a phase of a unstable ice advance.