The Nusfjord exhumed earthquake source (Lofoten, Norway): deep crustal seismicity driven by bending of the lower plate during continental collision
The origin of earthquakes in the lower crust at depth of 20-40 km, where dominantly ductile deformation is expected, is highly debated. Exhumed networks of lower crustal coeval pseudotachylytes (quenched frictional melt produced during seismic slip) and mylonites (produced during the post- and inter...
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ftunivhullir:oai:hull-repository.worktribe.com:3752753 2024-09-15T18:17:54+00:00 The Nusfjord exhumed earthquake source (Lofoten, Norway): deep crustal seismicity driven by bending of the lower plate during continental collision Menegon, Luca Campbell, Lucy Fagereng, Åke Pennacchioni, Giorgio 2020-05-04 https://hull-repository.worktribe.com/file/3752753/1/Published%20Abstract https://hull-repository.worktribe.com/output/3752753 https://doi.org/10.5194/egusphere-egu2020-7129 English eng https://hull-repository.worktribe.com/output/3752753 doi:https://doi.org/10.5194/egusphere-egu2020-7129 https://hull-repository.worktribe.com/file/3752753/1/Published%20Abstract doi:10.5194/egusphere-egu2020-7129 openAccess http://creativecommons.org/licenses/by/4.0 Presentation / Conference Contribution publishedVersion 2020 ftunivhullir https://doi.org/10.5194/egusphere-egu2020-7129 2024-07-15T14:12:00Z The origin of earthquakes in the lower crust at depth of 20-40 km, where dominantly ductile deformation is expected, is highly debated. Exhumed networks of lower crustal coeval pseudotachylytes (quenched frictional melt produced during seismic slip) and mylonites (produced during the post- and interseismic viscous creep) provide a snapshot of the earthquake cycle at anomalously deep conditions in the crust. Such natural laboratories offer the opportunity to investigate the origin and the tectonic setting of lower crustal earthquakes.The Nusfjord East shear zone network (Lofoten, northern Norway) represents an exhumed lower crustal earthquake source, where mutually overprinting mylonites and pseudotachylytes record the interplay between coseismic slip and viscous creep (Menegon et al., 2017; Campbell and Menegon, 2019). The network is well exposed over an area of 4 km2 and consists of three main intersecting sets of ductile shear zones ranging in width from 1 cm to 1 m, which commonly nucleate on former pseudotachylyte veins. Mutual crosscutting relationships indicate that the three sets were active at the same time. Amphibole-plagioclase geothermobarometry yields consistent P-T estimates in all three sets (700-750 °C, 0.7-0.8 GPa). The shear zones separate relatively undeformed blocks of anorthosite that contain pristine pseudotachylyte fault veins. These pseudotachylytes link adjacent or intersecting shear zones, and are interpreted as fossil seismogenic faults representing earthquake nucleation as a transient consequence of ongoing, localised aseismic creep along the shear zones (Campbell et al., under review).The coeval activity of the three shear zone sets is consistent with a local extensional setting, with a bulk vertical shortening and a horizontal NNW-SSE extension. This extension direction is subparallel to the convergence direction between Baltica and Laurentia during the Caledonian Orogeny, and with the dominant direction of nappe thrusting in the Scandinavian Caledonides. 40Ar‐39Ar dating of ... Other/Unknown Material Lofoten Northern Norway University of Hull: Repository@Hull |
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University of Hull: Repository@Hull |
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ftunivhullir |
language |
English |
description |
The origin of earthquakes in the lower crust at depth of 20-40 km, where dominantly ductile deformation is expected, is highly debated. Exhumed networks of lower crustal coeval pseudotachylytes (quenched frictional melt produced during seismic slip) and mylonites (produced during the post- and interseismic viscous creep) provide a snapshot of the earthquake cycle at anomalously deep conditions in the crust. Such natural laboratories offer the opportunity to investigate the origin and the tectonic setting of lower crustal earthquakes.The Nusfjord East shear zone network (Lofoten, northern Norway) represents an exhumed lower crustal earthquake source, where mutually overprinting mylonites and pseudotachylytes record the interplay between coseismic slip and viscous creep (Menegon et al., 2017; Campbell and Menegon, 2019). The network is well exposed over an area of 4 km2 and consists of three main intersecting sets of ductile shear zones ranging in width from 1 cm to 1 m, which commonly nucleate on former pseudotachylyte veins. Mutual crosscutting relationships indicate that the three sets were active at the same time. Amphibole-plagioclase geothermobarometry yields consistent P-T estimates in all three sets (700-750 °C, 0.7-0.8 GPa). The shear zones separate relatively undeformed blocks of anorthosite that contain pristine pseudotachylyte fault veins. These pseudotachylytes link adjacent or intersecting shear zones, and are interpreted as fossil seismogenic faults representing earthquake nucleation as a transient consequence of ongoing, localised aseismic creep along the shear zones (Campbell et al., under review).The coeval activity of the three shear zone sets is consistent with a local extensional setting, with a bulk vertical shortening and a horizontal NNW-SSE extension. This extension direction is subparallel to the convergence direction between Baltica and Laurentia during the Caledonian Orogeny, and with the dominant direction of nappe thrusting in the Scandinavian Caledonides. 40Ar‐39Ar dating of ... |
format |
Other/Unknown Material |
author |
Menegon, Luca Campbell, Lucy Fagereng, Åke Pennacchioni, Giorgio |
spellingShingle |
Menegon, Luca Campbell, Lucy Fagereng, Åke Pennacchioni, Giorgio The Nusfjord exhumed earthquake source (Lofoten, Norway): deep crustal seismicity driven by bending of the lower plate during continental collision |
author_facet |
Menegon, Luca Campbell, Lucy Fagereng, Åke Pennacchioni, Giorgio |
author_sort |
Menegon, Luca |
title |
The Nusfjord exhumed earthquake source (Lofoten, Norway): deep crustal seismicity driven by bending of the lower plate during continental collision |
title_short |
The Nusfjord exhumed earthquake source (Lofoten, Norway): deep crustal seismicity driven by bending of the lower plate during continental collision |
title_full |
The Nusfjord exhumed earthquake source (Lofoten, Norway): deep crustal seismicity driven by bending of the lower plate during continental collision |
title_fullStr |
The Nusfjord exhumed earthquake source (Lofoten, Norway): deep crustal seismicity driven by bending of the lower plate during continental collision |
title_full_unstemmed |
The Nusfjord exhumed earthquake source (Lofoten, Norway): deep crustal seismicity driven by bending of the lower plate during continental collision |
title_sort |
nusfjord exhumed earthquake source (lofoten, norway): deep crustal seismicity driven by bending of the lower plate during continental collision |
publishDate |
2020 |
url |
https://hull-repository.worktribe.com/file/3752753/1/Published%20Abstract https://hull-repository.worktribe.com/output/3752753 https://doi.org/10.5194/egusphere-egu2020-7129 |
genre |
Lofoten Northern Norway |
genre_facet |
Lofoten Northern Norway |
op_relation |
https://hull-repository.worktribe.com/output/3752753 doi:https://doi.org/10.5194/egusphere-egu2020-7129 https://hull-repository.worktribe.com/file/3752753/1/Published%20Abstract doi:10.5194/egusphere-egu2020-7129 |
op_rights |
openAccess http://creativecommons.org/licenses/by/4.0 |
op_doi |
https://doi.org/10.5194/egusphere-egu2020-7129 |
_version_ |
1810456034055028736 |