Middle Pleistocene landforms in the Danish Sector of the southern North Sea imaged on 3D seismic data
Published:January 01, 2012
Dagmar Müther, Stefan Back, Lars Reuning, Peter Kukla, Frank Lehmkuhl, 2012. "Middle Pleistocene landforms in the Danish Sector of the southern North Sea imaged on 3D seismic data", Glaciogenic Reservoirs and Hydrocarbon Systems, M. Huuse, J. Redfern, D. P. Le Heron, R. J. Dixon, A. Moscariello, J. Craig
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Despite a long history of investigation, several critical issues regarding the glacial history of NW Europe, particularly in currently marine areas, remain unsolved. In this study, we present a comprehensive three-dimensional (3D) seismic interpretation of an area measuring 2000 km2 in the western part of the Danish North Sea that exhibits several buried Quaternary landforms. Well data are used to assign minimum and maximum ages for the studied sedimentary succession. The most prominent buried landforms are three large-scale tunnel valleys of probable Saalian age that extend over more than 20 km across the western and southern part of the study area. These valleys most probably formed through subglacial meltwater erosion close to the termination of a former ice sheet. In the southern part of the study area, an extensive network of small-scale, dendritic seismic lineations interpreted as a palaeo-drainage system characterizes the landward termination of one major tunnel valley. This drainage system was active either contemporaneously or shortly after the development of the tunnel valley. Interpretation of this system as contemporaneous to tunnel-valley formation suggests that steady-state subglacial meltwater discharge was funnelled through a drainage system into the main tunnel valley. In contrast, interpretation of the drainage network as post-incisional points to the development of a post-glacial river system re-using the pre-existing tunnel valley as a downstream fluvial pathway. This uncertainty in the interpretation has important consequences for prediction of the rock content and reservoir characteristics of the tunnel-valley infill, in that either meltwater deposits or fluvial sediments form a considerable part of the tunnel-valley infill.
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Glaciogenic Reservoirs and Hydrocarbon Systems
Glaciogenic reservoirs and hydrocarbon systems occur intermittently throughout the stratigraphic record, with particular prominence in Neoproterozoic, Late Ordovician, Permo-Carboniferous and Late Cenozoic strata. Recent interest in glaciogenic successions has been fuelled by hydrocarbon discoveries in ancient glaciogenic reservoirs in North Africa, the Middle East, Australia and South America. Glaciogenic deposits of Pleistocene age are noteworthy for their content of groundwater onshore and potentially prospective and/or hazardous gas accumulations offshore. The abundant imprints of Pleistocene glaciations in both hemispheres can be used to reconstruct complex histories of repeated ice cover and retreat, and glacier-bed interactions, thus informing our view on the dynamics of older ice caps and predictions of future glaciations. This volume aims to provide a better understanding of glaciogenic processes, their stratigraphic record and reservoir characteristics of glaciogenic deposits. The book comprises 3 overview papers and 16 original case studies of Neoproterozoic to Pleistocene successions on 6 continents and will be of interest to sedimentologists, glaciologists, geophysicists, hydrologists and petroleum geologists alike.