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An onshore-offshore interpretation of structures in the Devonian rocks of the Pentland Firth, Scotland using high resolution bathymetry and drone-enabled field observations.

Utley, Thomas A.G.; Holdsworth, Robert E.; Walker, Richard J.; Dempsey, Edward D.; McCaffrey, Ken J.W.; Dichiarante, Anna; Jones, Thomas L.

An onshore-offshore interpretation of structures in the Devonian rocks of the Pentland Firth, Scotland using high resolution bathymetry and drone-enabled field observations. Thumbnail


Authors

Thomas A.G. Utley

Edward D. Dempsey

Anna Dichiarante

Thomas L. Jones



Abstract

Strong tidal currents in the Pentland Firth separating NE Scotland and Orkney have stripped recent seafloor sediments revealing geological structures in parts of the Devonian Orcadian Basin that are otherwise limited to narrow coastal outcrops. Here we interpret and analyse a 220 km2 high-resolution bathymetric dataset and combine these findings with onshore aerial imagery, field observations, and photogrammetric Virtual Outcrop Models created from coastal outcrops. This approach allows a reappraisal of the structure, stratigraphy and tectonic evolution of the Orcadian Basin, and gives new insights into fold and fault structures developed at sub-seismic to reservoir scales. A major basin-scale Devonian structure – the Brough-Brims-Risa Fault – can be traced from Caithness to Hoy and has partitioned reactivation-related deformation in the Orcadian Basin during later deformation episodes. Carboniferous inversion-related folds formed during E-W shortening are mapped and correlated between Caithness and Orkney. These structures are cross-cut by widespread highly connected fracture networks formed by steeply-dipping ENE-WSW and subordinate WNW-ESE trending structures developed during Permian NW-SE transtensional rifting. The offshore dataset demonstrates the continuity and topology of structures related to superimposed rifting and basin inversion events across a much greater scale range than was hitherto possible.

Citation

Utley, T. A., Holdsworth, R. E., Walker, R. J., Dempsey, E. D., McCaffrey, K. J., Dichiarante, A., & Jones, T. L. (2023). An onshore-offshore interpretation of structures in the Devonian rocks of the Pentland Firth, Scotland using high resolution bathymetry and drone-enabled field observations. Journal of Structural Geology, 174, Article 104922. https://doi.org/10.1016/j.jsg.2023.104922

Journal Article Type Article
Acceptance Date Jul 26, 2023
Online Publication Date Jul 29, 2023
Publication Date 2023-09
Deposit Date Sep 4, 2023
Publicly Available Date Sep 4, 2023
Journal Journal of Structural Geology
Print ISSN 0191-8141
Electronic ISSN 1873-1201
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 174
Article Number 104922
DOI https://doi.org/10.1016/j.jsg.2023.104922
Keywords Geology
Public URL https://durham-repository.worktribe.com/output/1729179

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