Quaternary environments of the central North Sea from basin-wide 3D seismic data

UoM administered thesis: Phd

  • Authors:
  • Rachel Lamb

Abstract

Climate change during the last 2.5 million years is characterised by glacial-interglacial cycles of fluctuating sea level and temperature increasing in magnitude and duration towards the present day. The central North Sea preserves these glacial-interglacial cycles in an expanded sedimentary sequence creating a high resolution palaeo-climatic record. Basin-wide, low-resolution 3D seismic data, covering more than 80,000 km2 of the central North Sea, is combined with high-resolution, broadband 3D seismic, regional 2D seismic and local ultra-high resolution seismic from the Dogger Bank windfarm development zone in order to investigate in full the sedimentary sequence. The evolution of the basin is analysed along with the preserved geomorphological landforms in order to build a framework for the development of the North Sea and its changing palaeo-environments from the inception of the Quaternary (2.58 Ma) until the extensive glacial unconformity formed during the Elsterian (0.48 Ma).At the onset of the Quaternary the structure of the North Sea was that of an elongate marine basin, rapidly infilled from the south by continued progradation of the large clinoformal deposits of the southern North Sea deltaic system. The basin rapidly decreased in extent and depth however it was not until around 1.1 Ma that the broad, shallow shelf of the present day was fully established. A revision of the current seismic stratigraphy is proposed, identifying four new Members within the Aberdeen Ground Formation taking into account the development of the basin through time.Powerful downslope gravity currents dominated the basin during much of the early Quaternary, although a well-established, anti-clockwise tidal gyre acted to gently modify the gravity currents. Iceberg scouring was nearly continual from the onset of the Quaternary until grounded ice sheets began to penetrate into the basin from 1.7 Ma, more than half a million years before any previous estimates. Effects of confluence of the British and Fennoscandian ice sheets are observed from 1.3 Ma. The tunnel valleys of the Dogger Bank represent a continuation of the North Sea tunnel valley network, interacting with both older glaciotectonic thrusting and younger glaciotectonic folded deformation.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
  • Mads Huuse (Supervisor)
  • Simon Brocklehurst (Supervisor)
Award date31 Dec 2016

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