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AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin

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Age determination of the volcanic sequence, Faroe-Shetland Basin, Northeast Atlantic Ocean

Abstract

In the Faroe-Shetland Basin a Paleocene to Early Eocene (T25-T45) sedimentary succession, stemming from the UK, interacts with the volcanic succession, originating from the Faroe Islands. The interaction and relative time relations, is studied from well and seismic data in order to obtain a consistent timing of the geological evolution of the area. The siliciclastic sequence is biostratigraphically dated from offshore well data whereas the volcanic sequence is both biostratigraphically and radiometrically dated from onshore samples. These two dating methods are not comparative and in addition to that, the two existing biostratigraphic studies are not comparative to each other. It can be mentioned that one of the biostratigraphic study support the radiometric dating method. Based on seismic interpretation in the central Faroe-Shetland Basin, the sedimentary succession can be extrapolated towards the west and the interpretation indicates that the upper part of the volcanic material is time equivalent to the Flett Formation as T40 is found below and T45 above the volcanic. The onshore coal bearing Prestfjall Formation (A-horizon) is identified as a bright reflector in offshore seismic data. The A-horizon is traced into the central Faroe-Shetland Basin, and corresponds here to the boundary between T40/F1A and T40/F1B. Seismic interpretation in the Judd Sub-basin show that the lower part of the volcanic succession recorded in the wells is time equivalent with Lamba (T36-T38) and Vaila (T25-T36) formations. Thus indirect age determination using dated sediment in wells and seismic interpretation place an age estimate of the volcanic material to be T25-T45 (possibly down to T22) which pronouncedly revise the dating of the volcanics and renews the idea of the geological development of the area, which is of importance regarding the hydrocarbon exploration.