Campbell, LR, Lloyd, GE orcid.org/0000-0002-7859-2486, Phillips, RJ et al. (2 more authors) (2020) Stress fields of ancient seismicity recorded in the dynamic geometry of pseudotachylyte in the Outer Hebrides Fault Zone, UK. Journal of the Geological Society. jgs2020-101. ISSN 0016-7649
Abstract
Heterogeneous sequences of exhumed fault rocks preserve a record of long-term evolution of fault strength and deformation behaviour during prolonged tectonic activity. Along the Outer Hebrides Fault Zone (OHFZ), UK, numerous pseudotachylytes record palaeoseismic slip events within sequences of mylonites, cataclasites and phyllonites.
To date, the kinematics and controls on seismicity within the long active history of the OHFZ have been poorly constrained. Additional uncertainties over the relative location of a meteorite impact and possible pre-OHFZ brittle faulting also complicates interpretation of the diffuse seismic record. This study presents kinematic analyses of seismicity in the OHFZ, combining observations of offset markers, en-echelon injection veins, and injection vein geometry to reconstruct slip directions and stress fields. This new dataset indicates that a range of fault orientations, slip directions and slip senses hosted seismicity in the OHFZ. Such complexity requires several stress field orientations, in contrast to NW-SE Caledonian compression traditionally attributed to frictional melting along the OHFZ, indicating that seismicity had a long-term presence across the fault zone. Persistence of strong frictional failure alongside the simultaneous development of weak fault rocks and phyllonitic shear zones in parts of the OHFZ has significant implications for understanding seismic hazard along mature continental faults.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Journal of the Geological Society, 2020. https://doi.org/10.1144/jgs2020-101. © 2020 The Author(s). Published by The Geological Society of London. All rights reserved. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 22 Oct 2020 15:50 |
Last Modified: | 01 Oct 2021 00:38 |
Status: | Published online |
Publisher: | Geological Society |
Identification Number: | 10.1144/jgs2020-101 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:166975 |