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The Application of Rift Segmentation Models to the Sub-Basalt Region of the Faroe-Shetland Basin, NE Atlantic Margin

Moy, David J.1; Imber, Jonathan 1; Ellis, David 2; Gallagher, Joseph W.2
1 Department of Earth Sciences, Durham University, Durham, United Kingdom.
2 Statoil UK Ltd, London, United Kingdom.

The NE Atlantic margin formed during Early Cenozoic continental break-up between NW Europe and Greenland following a protracted phase of crustal stretching. The rifts have a NE-SW orientation, but regional potential field datasets highlight a series of NW-SE trending lineaments or “transfer zones” along the length of the margin. The origin and significance of these lineaments is however unclear, but an improved geological understanding of these transfer zones is of practical interest to the hydrocarbon industry. This presentation synthesizes the results of a 3 year investigation into the structural and stratigraphic expression of transfer zones using well-calibrated 3D seismic reflection data from the Faroe-Shetland Basin and elsewhere along the NE Atlantic margin.

Seismic imaging of transfer zones within the Faroe-Shetland Basin is problematic due to a thick (up to 7km) Cenozoic lava and hyaloclastite succession deposited at the time of continental separation. Initial results focusing on the Mesozoic rift within the better-imaged UK sector have revealed a lack of seismically resolvable transfer zones. Nevertheless, ongoing sub-basalt seismic mapping, onshore field mapping and regional potential field interpretations point to the existence of clear NW-SE trends, primarily within the north-western (Cenozoic) part of the basin. Detailed tectono-stratigraphic analysis of sub-basalt structures is not possible with current datasets. The second part of this presentation therefore synthesizes and applies results obtained from a study of analogous structures within the better-imaged NW Vøring Basin, offshore Norway.

The NW Vøring Basin is characterized by two NE-SW trending structural highs, the Gjallar Ridge and Nyk High, which formed during Late Cretaceous-Paleocene rifting. The highs are offset in an apparent dextral sense across the NW-SE trending Rym Transfer Zone with a second NW-SE trending feature segmenting the Gjallar Ridge; here termed the Gleipne Accommodation Zone. The results suggest that although the two lineaments are likely to have contrasting structural and stratigraphic expressions, each structure impacted on the pre- to syn-breakup accommodation space within the basin. Application of these findings to the Faroe-Shetland basin suggest that structures analogous to the Rym Transfer Zone may be identified in the potential field data, but structures analogous to the Gleipne Accommodation Zone are not likely to be resolved using current datasets.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009