High-resolution 2D throw-depth mapping to assess the evolution and reactivation histories of outer-arc faults in buckle folds

Maunde, Abubakar and Alves, Tiago M. ORCID: https://orcid.org/0000-0002-2765-3760 2026. High-resolution 2D throw-depth mapping to assess the evolution and reactivation histories of outer-arc faults in buckle folds. Journal of Applied Geophysics , 106501. 10.1016/j.jappgeo.2026.106501

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Abstract

Tectonic shortening can induce a continuum of internal deformation in strata and leads to the generation of outer-arc extensional faults in evolving folds and structural traps. High-quality three-dimensional (3D) seismic and borehole data from the Southern North Sea are used in this work to investigate the geometry and growth histories of outer-arc extensional faults via a detailed analysis of fault throws vs. their depths (T-z plots). The results show that faults nucleated first in more competent sandy intervals - those recording the larger fault throws between 21.3 m and 41.1 m, and a high competency ratio above 1.0. They propagated outwards to link with fault segments developing in less competent shale-rich intervals. These softer shaley intervals record fault throws between 5.2 m and 19.6 m and competency ratios below 1.0. Throw-depth distributions suggest fault growth via segment linkage whereby the segments with the larger throws propagate outwards towards each other to then link to strata recording small fault throws. Fault traces are also narrower, more localised and less segmented compared to incompetent shale-rich intervals. Recognising the geometry and growth histories of outer-arc extensional faults as those in this work is crucial to understanding how faults evolve and grow near folds and horizontally shortened traps. It also provides information on the timing of fault activity, a parameter directly affecting sub-surface fluid flow and the sealing potential of faults in geological reservoirs. As a corollary, we show that the loci where outer-arc faults first nucleated and subsequently propagated from is recorded by anomalous fault-throw distributions.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Earth and Environmental Sciences Schools > Physical, Chemical & Environmental Sciences
Publisher:	Elsevier
ISSN:	0926-9851
Last Modified:	08 Sep 2026 08:45
URI:	https://orca.cardiff.ac.uk/id/eprint/189449

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