Slab portal beneath the western Aleutians
Tomographic images of the distribution of shear-wave speed beneath the northwestern Pacific delineate the configuration of the subducted oceanic lithosphere beneath the western Aleutian arc. At similar to 100 km depth, a fast shear-wave speed anomaly is beneath the Aleutian arc everywhere east of 17...
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Language: | English |
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ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_2809003 2023-05-15T16:59:15+02:00 Slab portal beneath the western Aleutians Levin, V. Shapiro, N. Park, J. Ritzwoller, M. 2005 https://gfzpublic.gfz-potsdam.de/pubman/item/item_2809003 eng eng info:eu-repo/semantics/altIdentifier/doi/10.1130/g20863.1 https://gfzpublic.gfz-potsdam.de/pubman/item/item_2809003 Geology info:eu-repo/semantics/article 2005 ftgfzpotsdam https://doi.org/10.1130/g20863.1 2022-09-14T05:56:36Z Tomographic images of the distribution of shear-wave speed beneath the northwestern Pacific delineate the configuration of the subducted oceanic lithosphere beneath the western Aleutian arc. At similar to 100 km depth, a fast shear-wave speed anomaly is beneath the Aleutian arc everywhere east of 173 degrees E. Between 164 degrees E and 173 degrees E, however, seismic velocities at this depth are slow relative to the surrounding mantle. The lateral termination of the fast shear-wave speed anomaly at depth coincides with a gap in deep seismicity beneath the Aleutians. The absence of these two distinctive traits of subducting slabs leads us to conclude that this segment of the Aleutian arc overlies a very large window in the otherwise continuous lithospheric slab that we term a "slab portal." This portal is likely to facilitate the production of distinctive volcanic rocks (adakites or high-Mg# andesites) by partially melting the adjacent edges of the slab. The Miocene age of most adakites in the westernmost Aleutians where no slab is present may indicate that the portal formed relatively recently. The chemistry of western Aleutian adakites approximates that of typical continental crust, so their genesis and subsequent lateral transport toward Kamchatka is a plausible mechanism for new continent formation. Article in Journal/Newspaper Kamchatka GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) Pacific The Portal ENVELOPE(159.167,159.167,-78.100,-78.100) Geology 33 4 253 |
institution |
Open Polar |
collection |
GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
op_collection_id |
ftgfzpotsdam |
language |
English |
description |
Tomographic images of the distribution of shear-wave speed beneath the northwestern Pacific delineate the configuration of the subducted oceanic lithosphere beneath the western Aleutian arc. At similar to 100 km depth, a fast shear-wave speed anomaly is beneath the Aleutian arc everywhere east of 173 degrees E. Between 164 degrees E and 173 degrees E, however, seismic velocities at this depth are slow relative to the surrounding mantle. The lateral termination of the fast shear-wave speed anomaly at depth coincides with a gap in deep seismicity beneath the Aleutians. The absence of these two distinctive traits of subducting slabs leads us to conclude that this segment of the Aleutian arc overlies a very large window in the otherwise continuous lithospheric slab that we term a "slab portal." This portal is likely to facilitate the production of distinctive volcanic rocks (adakites or high-Mg# andesites) by partially melting the adjacent edges of the slab. The Miocene age of most adakites in the westernmost Aleutians where no slab is present may indicate that the portal formed relatively recently. The chemistry of western Aleutian adakites approximates that of typical continental crust, so their genesis and subsequent lateral transport toward Kamchatka is a plausible mechanism for new continent formation. |
format |
Article in Journal/Newspaper |
author |
Levin, V. Shapiro, N. Park, J. Ritzwoller, M. |
spellingShingle |
Levin, V. Shapiro, N. Park, J. Ritzwoller, M. Slab portal beneath the western Aleutians |
author_facet |
Levin, V. Shapiro, N. Park, J. Ritzwoller, M. |
author_sort |
Levin, V. |
title |
Slab portal beneath the western Aleutians |
title_short |
Slab portal beneath the western Aleutians |
title_full |
Slab portal beneath the western Aleutians |
title_fullStr |
Slab portal beneath the western Aleutians |
title_full_unstemmed |
Slab portal beneath the western Aleutians |
title_sort |
slab portal beneath the western aleutians |
publishDate |
2005 |
url |
https://gfzpublic.gfz-potsdam.de/pubman/item/item_2809003 |
long_lat |
ENVELOPE(159.167,159.167,-78.100,-78.100) |
geographic |
Pacific The Portal |
geographic_facet |
Pacific The Portal |
genre |
Kamchatka |
genre_facet |
Kamchatka |
op_source |
Geology |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1130/g20863.1 https://gfzpublic.gfz-potsdam.de/pubman/item/item_2809003 |
op_doi |
https://doi.org/10.1130/g20863.1 |
container_title |
Geology |
container_volume |
33 |
container_issue |
4 |
container_start_page |
253 |
_version_ |
1766051478960603136 |