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Understanding the offshore flood basalt sequence using onshore volcanic facies analogues: an example from the Faroe-Shetland basin

Jerram, Dougal A.; Single, Richard T.; Hobbs, Richard W.; Nelson, Catherine E

Understanding the offshore flood basalt sequence using onshore volcanic facies analogues: an example from the Faroe-Shetland basin Thumbnail


Authors

Dougal A. Jerram

Richard T. Single

Richard W. Hobbs

Catherine E Nelson



Abstract

Flood basalts in associated volcanic rifled margins, such as the North Atlantic Igneous Province, have a significant component of lavas which are preserved in the present clay in an offshore setting. A close inspection of the internal facies architecture of flood basalts onshore provides a framework to interpret the offshore sequences imaged by remote techniques such as reflection seismology. A geological interpretation of the offshore lava sequences in the Faroe-Shetland Basin, using constraints from onshore analogues such as the Faroe Islands, allows for the identification of a series of lava sequences which have characteristic properties so that they can be grouped. These are tabular simple flows, compound-braided flows, and sub-aqueously deposited hyaloclastite facies. The succession of volcanic rocks calculated in this study has a maximum thickness in excess of 6800 m. Down to the top of the sub-volcanic sediments, the offshore volcanic succession has a thickness of about 2700 m where it can be clearly identified across much of the area, with a further 2700 m or more of volcanic rock estimated from the combined gravity and seismic modelling to the north and west of the region. A large palaeo-waterbody is identified oil the basis of a hyaloclastite front/apron consisting of a series of clinoforms prograding towards the eastern part of the basin. This body was > 500 m deep, must have been present at the onset of volcanism into this region, and parts of, the water body would have been present during the continued stages of volcanism as indicated by the distribution of the hyaloclastite apron.

Citation

Jerram, D. A., Single, R. T., Hobbs, R. W., & Nelson, C. E. (2009). Understanding the offshore flood basalt sequence using onshore volcanic facies analogues: an example from the Faroe-Shetland basin. Geological Magazine, 146(3), 353-367. https://doi.org/10.1017/s0016756809005974

Journal Article Type Article
Publication Date May 1, 2009
Deposit Date May 25, 2010
Publicly Available Date Mar 29, 2024
Journal Geological Magazine
Print ISSN 0016-7568
Electronic ISSN 1469-5081
Publisher Cambridge University Press
Peer Reviewed Peer Reviewed
Volume 146
Issue 3
Pages 353-367
DOI https://doi.org/10.1017/s0016756809005974
Keywords British Tertiary, LIP, Hyaloclastite, Lava sequences.

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