Assessing the Role of Water in Alaskan Flat‐Slab Subduction
Abstract Low‐angle subduction has been shown to have a profound impact on subduction processes. However, the mechanisms that initiate, drive, and sustain flat‐slab subduction are debated. Within all subduction zone systems, metamorphic dehydration reactions within the down‐going slab have been hypot...
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ftdoajarticles:oai:doaj.org/article:5182b4961549427bb2efc542e40c180b 2023-12-03T10:31:40+01:00 Assessing the Role of Water in Alaskan Flat‐Slab Subduction Sarah E. Petersen Thomas D. Hoisch Ryan C. Porter 2021-05-01T00:00:00Z https://doi.org/10.1029/2021GC009734 https://doaj.org/article/5182b4961549427bb2efc542e40c180b EN eng Wiley https://doi.org/10.1029/2021GC009734 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2021GC009734 https://doaj.org/article/5182b4961549427bb2efc542e40c180b Geochemistry, Geophysics, Geosystems, Vol 22, Iss 5, Pp n/a-n/a (2021) Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.1029/2021GC009734 2023-11-05T01:36:02Z Abstract Low‐angle subduction has been shown to have a profound impact on subduction processes. However, the mechanisms that initiate, drive, and sustain flat‐slab subduction are debated. Within all subduction zone systems, metamorphic dehydration reactions within the down‐going slab have been hypothesized to produce seismicity, and to produce water that fluxes melting of the asthenospheric wedge leading to arc magmatism. In this work, we examine the role hydration plays in influencing slab buoyancy and the geometry of the downgoing oceanic plate. When water is introduced to the oceanic lithosphere, it is incorporated into hydrous phases, which results in lowered rock densities. The net effect of this process is an increase in the buoyancy of the downgoing oceanic lithosphere. To better understand the role of water in low‐angle subduction settings, we model flat‐slab subduction in Alaska, where the thickened oceanic lithosphere of the Yakutat oceanic plateau is subducting beneath the continental lithosphere. In this work, we calculate the thermal conditions and stable mineral assemblages in the slab crust and mantle in order to assess the role that water plays in altering the density of the subducting slab. Our slab density results show that a moderate amount of hydration (1–1.5 wt% H2O) in the subducting crust and upper lithospheric mantle reduces slab density by 0.5%–0.8% relative to an anhydrous slab, and is sufficient to maintain slab buoyancy to 300–400 km from the trench. These models show that water is a viable factor in influencing the subduction geometry in Alaska, and is likely important globally. Article in Journal/Newspaper Yakutat Alaska Directory of Open Access Journals: DOAJ Articles Geochemistry, Geophysics, Geosystems 22 5 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
spellingShingle |
Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 Sarah E. Petersen Thomas D. Hoisch Ryan C. Porter Assessing the Role of Water in Alaskan Flat‐Slab Subduction |
topic_facet |
Geophysics. Cosmic physics QC801-809 Geology QE1-996.5 |
description |
Abstract Low‐angle subduction has been shown to have a profound impact on subduction processes. However, the mechanisms that initiate, drive, and sustain flat‐slab subduction are debated. Within all subduction zone systems, metamorphic dehydration reactions within the down‐going slab have been hypothesized to produce seismicity, and to produce water that fluxes melting of the asthenospheric wedge leading to arc magmatism. In this work, we examine the role hydration plays in influencing slab buoyancy and the geometry of the downgoing oceanic plate. When water is introduced to the oceanic lithosphere, it is incorporated into hydrous phases, which results in lowered rock densities. The net effect of this process is an increase in the buoyancy of the downgoing oceanic lithosphere. To better understand the role of water in low‐angle subduction settings, we model flat‐slab subduction in Alaska, where the thickened oceanic lithosphere of the Yakutat oceanic plateau is subducting beneath the continental lithosphere. In this work, we calculate the thermal conditions and stable mineral assemblages in the slab crust and mantle in order to assess the role that water plays in altering the density of the subducting slab. Our slab density results show that a moderate amount of hydration (1–1.5 wt% H2O) in the subducting crust and upper lithospheric mantle reduces slab density by 0.5%–0.8% relative to an anhydrous slab, and is sufficient to maintain slab buoyancy to 300–400 km from the trench. These models show that water is a viable factor in influencing the subduction geometry in Alaska, and is likely important globally. |
format |
Article in Journal/Newspaper |
author |
Sarah E. Petersen Thomas D. Hoisch Ryan C. Porter |
author_facet |
Sarah E. Petersen Thomas D. Hoisch Ryan C. Porter |
author_sort |
Sarah E. Petersen |
title |
Assessing the Role of Water in Alaskan Flat‐Slab Subduction |
title_short |
Assessing the Role of Water in Alaskan Flat‐Slab Subduction |
title_full |
Assessing the Role of Water in Alaskan Flat‐Slab Subduction |
title_fullStr |
Assessing the Role of Water in Alaskan Flat‐Slab Subduction |
title_full_unstemmed |
Assessing the Role of Water in Alaskan Flat‐Slab Subduction |
title_sort |
assessing the role of water in alaskan flat‐slab subduction |
publisher |
Wiley |
publishDate |
2021 |
url |
https://doi.org/10.1029/2021GC009734 https://doaj.org/article/5182b4961549427bb2efc542e40c180b |
genre |
Yakutat Alaska |
genre_facet |
Yakutat Alaska |
op_source |
Geochemistry, Geophysics, Geosystems, Vol 22, Iss 5, Pp n/a-n/a (2021) |
op_relation |
https://doi.org/10.1029/2021GC009734 https://doaj.org/toc/1525-2027 1525-2027 doi:10.1029/2021GC009734 https://doaj.org/article/5182b4961549427bb2efc542e40c180b |
op_doi |
https://doi.org/10.1029/2021GC009734 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
22 |
container_issue |
5 |
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1784258094404993024 |