MORGAN, RICHARD, STEVE HOLLINGWORTH, STEVE MERLIN, DANNY GRAHAM, and BOB GOSLING, Veritas DGC Ltd, Crawley, W. Sussex, U.K.

Abstract: The Structure of the Eastern Margin of the Faroe Volcanic Plateau as Imaged by Pre-stack Depth Migrated Seismic Data

Seismic imaging problems caused by layered, Palaeocene-early Eocene volcanic flows, which occur across large parts of the Faroe-Shetland Basin, have been ameliorated through the use of pre-stack depth imaging techniques. The combined development of velocity and geological models towards a shared interpretation has provided valuable geological insight in an area without well control, through the use of the velocity information inherent in the seismic data. The velocity models infer the volcanic pile to be seismically heterogeneous, suggesting a mixed composition of basalt flows and volcaniclastics. Volcanic escarpments have formed along the margin of the plateau creating easterly dipping slope faces, many hundreds of metres in height. These are considered to represent advancing palaeoshore-faces formed during periods of expansion of the volcanic plateau.

At least two phases of escarpment building are recognised, one contemporaneous with the Middle-Upper Series divisions recognised on the Faroe Islands, and giving rise to the Faroe-Shetland Escarpment, and an earlier phase expressed in the south eastern part of the margin, which correlates broadly with the Lower Series volcanic division. The older escarpment has been completely buried by sediment and by the later volcanic events which were not escarpment building in this part of the margin.The enormous thickness of accumulated volcanics (in excess of 15 km in some areas), and the fact that the uppermost layers of the volcanic pile are interdigitated with marine sediments, infers substantial and rapid subsidence to have occurred during volcanism.

AAPG Search and Discovery Article #90923@1999 International Conference and Exhibition, Birmingham, England