The Neogene stratigraphy of the glaciated European margin from Lofoten to Porcupine. Atlas - A product of the EC-supported STRATAGEM project..

M.S. Stoker, Tove Nielsen, Partners STRATAGEM

Publikation: Working paper eller internetudgivelseInternetpublikationForskning

Abstrakt

This stratigraphic atlas is one of two major products of the EC-supported STRATAGEM project; STRATAGEM is an acronym for 'Stratigraphic Development of the Glaciated European Margin'. The second main product of the project will be an evolutionary model for the area covered by the study, which will build upon the regional stratigraphic framework.

This volume presents a unified stratigraphic scheme for the Neogene (Miocene–Holocene) succession preserved along the Atlantic margin of NW Europe. The format and layout of this volume closely follows the style of presentation adopted for similar atlases published by the British Geological Survey (BGS), e.g. Stoker (1999), off NW Britain. This study combines lithostratigraphic and biostratigraphic data with a seismic-sequence stratigraphic framework derived from the integration of regional grids of high-resolution and commercial seismic-reflection profiles. The overall aim of this work has been to produce a Neogene stratigraphic framework that can be applied both to seismic and borehole/well data, and which will have the widest acceptance within the scientific community and industry. An additional element to this volume is a summary of the high-resolution stratigraphy for the middle Pleistocene–Holocene sediment record.

The area covered by this volume is the European Atlantic continental margin that has been influenced by glaciation, extending southwards from the Lofoten Islands off Mid-Norway (about 68ºN) to the Porcupine Seabight (about 50ºN) off SW Ireland. The continental margin is here taken to include the middle to outer shelf and slope of the Vøring, Møre, northern North Sea, Faroe–Shetland, Hebrides, Malin, Irish, Porcupine and Rockall margins and the adjacent deep-water areas of the Norwegian Basin, Faroe-Shetland/Faroe Bank Channel, Rockall Trough and Porcupine Seabight (Fig. 1).

The database utilised in the establishment of the Neogene framework consists of tens of thousands of line-kilometres of seismic-reflection data, 20 BGS shallow boreholes, 9 BGS rockdrill cores, 4 Irish shallow boreholes, 2 Deep Sea Drilling Project (DSDP) sites, 4 Ocean Drilling Program (ODP) sites and 37 released commercial wells and geotechnical borings (Fig. 2). Supplementary information was derived from published sources. Additionally, 36 short cores and 3 commercial geotechnical borings were utilised for the high-resolution stratigraphy.

The fundamental objectives of this study were to simplify the stratigraphic nomenclature and establish a unified regional stratigraphic classification and framework. To achieve an effective stratigraphic analysis, it was essential to recognise the correct level and method of correlation. Seismic-sequence stratigraphy represents the most practical approach to subdividing and correlating the Neogene succession on a regional basis, as this technique produces the most realistic stratigraphic correlation over large geographic areas, especially in frontier regions such as the NW European Atlantic margin. The seismic-sequence stratigraphic concept used in this volume follows the Geological Society's guide to stratigraphic procedure (Whittaker et al. 1991). The basis of the method is to use an integrated geological/geophysical database to define the sedimentary record in terms of depositional sequences. Emphasis has been placed on the establishment of megasequences, which bring together units that constitute important genetic packages. This level of mapping was deemed most appropriate in the establishment of a regional framework, as the development of megasequences tends to reflect major changes in continental margin evolution. Major phases of change are typically manifest by regional unconformities that form the megasequence boundaries (Hubbard et al. 1985). These boundaries are key elements in offshore sub-surface analysis and provide a first-order control on regional correlation. It should be noted that the Neogene succession has previously been subdivided into a multitude of seismic-stratigraphic units at various locations along the margin (e.g. Stoker et al. 1993; Rokoengen et al. 1995; King et al. 1996; McNeill et al. 1998; Andersen et al. 2000; Evans et al. 2002) which, over time, has resulted in a confusing plethora of stratigraphic terms. This new scheme aims to greatly simplify the stratigraphic nomenclature, yet provide a context for future, more detailed subdivision and meaningful correlation of the succession.
OriginalsprogEngelsk
UdgiverSTRATAGEM project
StatusUdgivet - 2002

Programområde

  • Programområde 3: Energiressourcer

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