Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary
The Nootka fault zone is a ridge‐trench‐trench transform fault that was initiated ~4 Ma when the Explorer ridge became independent of the Juan de Fuca ridge. Multibeam data around the fault zone and a compilation of several seismic reflection surveys provide insight into initiation of strike‐slip fa...
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Online Access: | https://oceanrep.geomar.de/id/eprint/44937/ https://oceanrep.geomar.de/id/eprint/44937/1/Rohr_Riedel_2018.pdf https://doi.org/10.1029/2018GC007851 |
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ftoceanrep:oai:oceanrep.geomar.de:44937 2023-05-15T17:12:07+02:00 Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary Rohr, Kristin M. M. Furlong, Kevin P. Riedel, Michael 2018-10-13 text https://oceanrep.geomar.de/id/eprint/44937/ https://oceanrep.geomar.de/id/eprint/44937/1/Rohr_Riedel_2018.pdf https://doi.org/10.1029/2018GC007851 en eng AGU (American Geophysical Union) Wiley https://oceanrep.geomar.de/id/eprint/44937/1/Rohr_Riedel_2018.pdf Rohr, K. M. M. , Furlong, K. P. and Riedel, M. (2018) Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary. Open Access Geochemistry, Geophysics, Geosystems, 19 (11). pp. 4290-4312. DOI 10.1029/2018GC007851 <https://doi.org/10.1029/2018GC007851>. doi:10.1029/2018GC007851 info:eu-repo/semantics/openAccess Article PeerReviewed 2018 ftoceanrep https://doi.org/10.1029/2018GC007851 2023-04-07T15:42:30Z The Nootka fault zone is a ridge‐trench‐trench transform fault that was initiated ~4 Ma when the Explorer ridge became independent of the Juan de Fuca ridge. Multibeam data around the fault zone and a compilation of several seismic reflection surveys provide insight into initiation of strike‐slip faults. Previous interpretations assumed that the two faults seen cutting the seafloor are subparallel to shear between the Explorer and Juan de Fuca plates and formed instantaneously at 4 Ma. Increased data density shows that these faults are subparallel to seafloor magnetic anomalies and appear to have utilized extensional faults formed at the ridge. They are surrounded by numerous buried steeply dipping, small‐offset growth faults; at least some of which are likely still active. Our observations corroborate analogue models of strike‐slip fault initiation that predict formation of Riedel‐like shears within a zone of faulting and that displacement localizes over time. The existence of several long subparallel faults and a very wide zone of faulting has been predicted by models of distributed shear at depth. Along the Nootka fault zone basement has risen by several hundred meters and bright reversed‐polarity reflectors some of which are interpreted to be methane hydrate reflectors are common. Hydration, likely as serpentinization, of the upper mantle could explain both sets of observations: Serpentinization can result in a 30–50% volume expansion and methane is observed in vents driven by this process. Biogenic sources of methane are likely to be present and concentrated by currently active fluid flow in the faulted sediments. Article in Journal/Newspaper Methane hydrate OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Geochemistry, Geophysics, Geosystems 19 11 4290 4312 |
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Open Polar |
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OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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ftoceanrep |
language |
English |
description |
The Nootka fault zone is a ridge‐trench‐trench transform fault that was initiated ~4 Ma when the Explorer ridge became independent of the Juan de Fuca ridge. Multibeam data around the fault zone and a compilation of several seismic reflection surveys provide insight into initiation of strike‐slip faults. Previous interpretations assumed that the two faults seen cutting the seafloor are subparallel to shear between the Explorer and Juan de Fuca plates and formed instantaneously at 4 Ma. Increased data density shows that these faults are subparallel to seafloor magnetic anomalies and appear to have utilized extensional faults formed at the ridge. They are surrounded by numerous buried steeply dipping, small‐offset growth faults; at least some of which are likely still active. Our observations corroborate analogue models of strike‐slip fault initiation that predict formation of Riedel‐like shears within a zone of faulting and that displacement localizes over time. The existence of several long subparallel faults and a very wide zone of faulting has been predicted by models of distributed shear at depth. Along the Nootka fault zone basement has risen by several hundred meters and bright reversed‐polarity reflectors some of which are interpreted to be methane hydrate reflectors are common. Hydration, likely as serpentinization, of the upper mantle could explain both sets of observations: Serpentinization can result in a 30–50% volume expansion and methane is observed in vents driven by this process. Biogenic sources of methane are likely to be present and concentrated by currently active fluid flow in the faulted sediments. |
format |
Article in Journal/Newspaper |
author |
Rohr, Kristin M. M. Furlong, Kevin P. Riedel, Michael |
spellingShingle |
Rohr, Kristin M. M. Furlong, Kevin P. Riedel, Michael Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary |
author_facet |
Rohr, Kristin M. M. Furlong, Kevin P. Riedel, Michael |
author_sort |
Rohr, Kristin M. M. |
title |
Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary |
title_short |
Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary |
title_full |
Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary |
title_fullStr |
Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary |
title_full_unstemmed |
Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary |
title_sort |
initiation of strike‐slip faults, serpentinization, and methane: the nootka fault zone, the juan de fuca‐explorer plate boundary |
publisher |
AGU (American Geophysical Union) |
publishDate |
2018 |
url |
https://oceanrep.geomar.de/id/eprint/44937/ https://oceanrep.geomar.de/id/eprint/44937/1/Rohr_Riedel_2018.pdf https://doi.org/10.1029/2018GC007851 |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_relation |
https://oceanrep.geomar.de/id/eprint/44937/1/Rohr_Riedel_2018.pdf Rohr, K. M. M. , Furlong, K. P. and Riedel, M. (2018) Initiation of Strike‐Slip Faults, Serpentinization, and Methane: The Nootka Fault Zone, the Juan de Fuca‐Explorer Plate Boundary. Open Access Geochemistry, Geophysics, Geosystems, 19 (11). pp. 4290-4312. DOI 10.1029/2018GC007851 <https://doi.org/10.1029/2018GC007851>. doi:10.1029/2018GC007851 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1029/2018GC007851 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
19 |
container_issue |
11 |
container_start_page |
4290 |
op_container_end_page |
4312 |
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1766068892906553344 |