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Reactivation of intrabasement structures during rifting: A case study from offshore southern Norway

Phillips, Thomas B.; Jackson, Christopher A-L.; Bell, Rebecca E.; Duffy, Oliver B.; Fossen, Haakon

Reactivation of intrabasement structures during rifting: A case study from offshore southern Norway Thumbnail


Authors

Thomas B. Phillips

Christopher A-L. Jackson

Rebecca E. Bell

Oliver B. Duffy

Haakon Fossen



Abstract

Pre-existing structures within crystalline basement may exert a significant influence over the evolution of rifts. However, the exact manner in which these structures reactivate and thus their degree of influence over the overlying rift is poorly understood. Using borehole-constrained 2D and 3D seismic reflection data from offshore southern Norway we identify and constrain the three-dimensional geometry of a series of enigmatic intrabasement reflections. Through 1D waveform modelling and 3D mapping of these reflection packages, we correlate them to the onshore Caledonian thrust belt and Devonian shear zones. Based on the seismic-stratigraphic architecture of the post-basement succession, we identify several phases of reactivation of the intrabasement structures associated with multiple tectonic events. Reactivation preferentially occurs along relatively thick (c. 1 km), relatively steeply dipping (c. 30°) structures, with three main styles of interactions observed between them and overlying faults: i) faults exploiting intrabasement weaknesses represented by intra-shear zone mylonites; ii) faults that initiate within the hangingwall of the shear zones, inheriting their orientation and merging with said structure at depth; or iii) faults that initiate independently from and cross-cut intrabasement structures. We demonstrate that large-scale discrete shear zones act as a long-lived structural template for fault initiation during multiple phases of rifting.

Journal Article Type Article
Acceptance Date Aug 16, 2016
Online Publication Date Aug 20, 2016
Publication Date Oct 31, 2016
Deposit Date Dec 19, 2018
Publicly Available Date Mar 22, 2019
Journal Journal of Structural Geology
Print ISSN 0191-8141
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 91
Pages 54-73
DOI https://doi.org/10.1016/j.jsg.2016.08.008
Public URL https://durham-repository.worktribe.com/output/1340932
Related Public URLs https://eartharxiv.org/ak5yb/

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