High transient stress in the lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten Archipelago, northern Norway
Seismic activity below the standard seismogenic zone is difficult to investigate because the geological records of such earthquakes, pseudotachylytes, are typically reacted and/or deformed. Here, we describe unusually pristine pseudotachylytes in lower-crustal granulites from the Lofoten Archipelago...
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Freie Universität Berlin
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ftdatacite:10.17169/refubium-30060 2023-05-15T17:08:15+02:00 High transient stress in the lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten Archipelago, northern Norway Dunkel, Kristina G. Zhong, Xin Arnestad, Paal Ferdinand Valen, Lars Vesterager Jamtveit, Bjørn 2021 https://dx.doi.org/10.17169/refubium-30060 https://refubium.fu-berlin.de/handle/fub188/30320 unknown Freie Universität Berlin https://doi.org/10.1130/G48002.1 https://dx.doi.org/10.1130/g48002.1 https://doi.org/10.1130/G48002.1 Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode cc-by-4.0 CC-BY intermediate-depth earthquakes facies pseudotachylytes musgrave ranges shear zones constraints equilibria transition mylonites 500 Naturwissenschaften und Mathematik550 Geowissenschaften, Geologie551 Geologie, Hydrologie, Meteorologie Text article-journal Wissenschaftlicher Artikel ScholarlyArticle 2021 ftdatacite https://doi.org/10.17169/refubium-30060 https://doi.org/10.1130/g48002.1 2021-11-05T12:55:41Z Seismic activity below the standard seismogenic zone is difficult to investigate because the geological records of such earthquakes, pseudotachylytes, are typically reacted and/or deformed. Here, we describe unusually pristine pseudotachylytes in lower-crustal granulites from the Lofoten Archipelago, northern Norway. The pseudotachylytes have essentially the same mineralogical composition as their host (mainly plagioclase, alkali feldspar, orthopyroxene) and contain microstructures indicative of rapid cooling, i.e., feldspar microlites and spherulites and "cauliflower" garnets. Mylonites are absent, both in the wall rocks and among the pseudotachylyte clasts. The absence of features recording precursory ductile deformation rules out several commonly invoked mechanisms for triggering earthquakes in the lower crust, including thermal runaway, plastic instabilities, and downward propagation of seismic slip from the brittle to the ductile part of a fault. The anhydrous mineralogy of host and pseudotachylytes excludes dehydration-induced embrittlement. In the absence of such weakening mechanisms, stress levels in the lower crust must have been transiently high. Text Lofoten Northern Norway DataCite Metadata Store (German National Library of Science and Technology) Lofoten Norway Wall Rocks ENVELOPE(-129.312,-129.312,52.728,52.728) |
institution |
Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
unknown |
topic |
intermediate-depth earthquakes facies pseudotachylytes musgrave ranges shear zones constraints equilibria transition mylonites 500 Naturwissenschaften und Mathematik550 Geowissenschaften, Geologie551 Geologie, Hydrologie, Meteorologie |
spellingShingle |
intermediate-depth earthquakes facies pseudotachylytes musgrave ranges shear zones constraints equilibria transition mylonites 500 Naturwissenschaften und Mathematik550 Geowissenschaften, Geologie551 Geologie, Hydrologie, Meteorologie Dunkel, Kristina G. Zhong, Xin Arnestad, Paal Ferdinand Valen, Lars Vesterager Jamtveit, Bjørn High transient stress in the lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten Archipelago, northern Norway |
topic_facet |
intermediate-depth earthquakes facies pseudotachylytes musgrave ranges shear zones constraints equilibria transition mylonites 500 Naturwissenschaften und Mathematik550 Geowissenschaften, Geologie551 Geologie, Hydrologie, Meteorologie |
description |
Seismic activity below the standard seismogenic zone is difficult to investigate because the geological records of such earthquakes, pseudotachylytes, are typically reacted and/or deformed. Here, we describe unusually pristine pseudotachylytes in lower-crustal granulites from the Lofoten Archipelago, northern Norway. The pseudotachylytes have essentially the same mineralogical composition as their host (mainly plagioclase, alkali feldspar, orthopyroxene) and contain microstructures indicative of rapid cooling, i.e., feldspar microlites and spherulites and "cauliflower" garnets. Mylonites are absent, both in the wall rocks and among the pseudotachylyte clasts. The absence of features recording precursory ductile deformation rules out several commonly invoked mechanisms for triggering earthquakes in the lower crust, including thermal runaway, plastic instabilities, and downward propagation of seismic slip from the brittle to the ductile part of a fault. The anhydrous mineralogy of host and pseudotachylytes excludes dehydration-induced embrittlement. In the absence of such weakening mechanisms, stress levels in the lower crust must have been transiently high. |
format |
Text |
author |
Dunkel, Kristina G. Zhong, Xin Arnestad, Paal Ferdinand Valen, Lars Vesterager Jamtveit, Bjørn |
author_facet |
Dunkel, Kristina G. Zhong, Xin Arnestad, Paal Ferdinand Valen, Lars Vesterager Jamtveit, Bjørn |
author_sort |
Dunkel, Kristina G. |
title |
High transient stress in the lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten Archipelago, northern Norway |
title_short |
High transient stress in the lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten Archipelago, northern Norway |
title_full |
High transient stress in the lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten Archipelago, northern Norway |
title_fullStr |
High transient stress in the lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten Archipelago, northern Norway |
title_full_unstemmed |
High transient stress in the lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten Archipelago, northern Norway |
title_sort |
high transient stress in the lower crust: evidence from dry pseudotachylytes in granulites, lofoten archipelago, northern norway |
publisher |
Freie Universität Berlin |
publishDate |
2021 |
url |
https://dx.doi.org/10.17169/refubium-30060 https://refubium.fu-berlin.de/handle/fub188/30320 |
long_lat |
ENVELOPE(-129.312,-129.312,52.728,52.728) |
geographic |
Lofoten Norway Wall Rocks |
geographic_facet |
Lofoten Norway Wall Rocks |
genre |
Lofoten Northern Norway |
genre_facet |
Lofoten Northern Norway |
op_relation |
https://doi.org/10.1130/G48002.1 https://dx.doi.org/10.1130/g48002.1 https://doi.org/10.1130/G48002.1 |
op_rights |
Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode cc-by-4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.17169/refubium-30060 https://doi.org/10.1130/g48002.1 |
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1766063956146782208 |