Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data
New results from wide-angle seismic data collected parallel to the central Aleutian island arc require an intermediate to mafic composition for the middle crust and a mafic to ultramafic composition for the lower crust and yield lateral velocity variations that correspond to arc segmentation and tre...
Published in: | Geochemistry, Geophysics, Geosystems |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
2004
|
Subjects: | |
Online Access: | https://eprints.soton.ac.uk/15819/ |
id |
ftsouthampton:oai:eprints.soton.ac.uk:15819 |
---|---|
record_format |
openpolar |
spelling |
ftsouthampton:oai:eprints.soton.ac.uk:15819 2023-07-30T03:55:47+02:00 Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data Shillington, Donna J. Van Avendonk, Harm J.A. Holbrook, W. Steven Keleman, Peter B. Hornbach, Matthew J. 2004 https://eprints.soton.ac.uk/15819/ unknown Shillington, Donna J., Van Avendonk, Harm J.A., Holbrook, W. Steven, Keleman, Peter B. and Hornbach, Matthew J. (2004) Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data. Geochemistry, Geophysics, Geosystems, 5 (10), 1-32. (doi:10.1029/2004GC000715 <http://dx.doi.org/10.1029/2004GC000715>). Article PeerReviewed 2004 ftsouthampton https://doi.org/10.1029/2004GC000715 2023-07-09T20:33:26Z New results from wide-angle seismic data collected parallel to the central Aleutian island arc require an intermediate to mafic composition for the middle crust and a mafic to ultramafic composition for the lower crust and yield lateral velocity variations that correspond to arc segmentation and trends in major element geochemistry. The 3-D ray tracing/2.5-D inversion of this sparse wide-angle data set, which incorporates independent phase interpretations and new constraints on shallow velocity structure, produces a faster and smoother result than a previously published velocity model. Middle-crustal velocities of 6.5–7.3 km/s over depths of ~10–20 km indicate an andesitic to basaltic composition. High lower-crustal velocities of 7.3–7.7 km/s over depths of ~20–35 km are interpreted as ultramafic-mafic cumulates and/or garnet granulites. The total crustal thickness is 35–37 km. This result indicates that the Aleutian island arc has higher velocities, and thus more mafic compositions, than average continental crust, implying that significant modifications would be required for this arc to be a suitable building block for continental crust. Lateral variations in average crustal velocity (below 10 km) roughly correspond to trends in major element geochemistry of primitive (Mg # > 0.6) lavas. The highest lower-crustal velocities (and presumably most mafic material) are detected in the center of an arc segment, between Unmak and Unalaska Islands, implying that arc segmentation exerts control over crustal composition. Article in Journal/Newspaper Aleutian Island University of Southampton: e-Prints Soton Geochemistry, Geophysics, Geosystems 5 10 n/a n/a |
institution |
Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
unknown |
description |
New results from wide-angle seismic data collected parallel to the central Aleutian island arc require an intermediate to mafic composition for the middle crust and a mafic to ultramafic composition for the lower crust and yield lateral velocity variations that correspond to arc segmentation and trends in major element geochemistry. The 3-D ray tracing/2.5-D inversion of this sparse wide-angle data set, which incorporates independent phase interpretations and new constraints on shallow velocity structure, produces a faster and smoother result than a previously published velocity model. Middle-crustal velocities of 6.5–7.3 km/s over depths of ~10–20 km indicate an andesitic to basaltic composition. High lower-crustal velocities of 7.3–7.7 km/s over depths of ~20–35 km are interpreted as ultramafic-mafic cumulates and/or garnet granulites. The total crustal thickness is 35–37 km. This result indicates that the Aleutian island arc has higher velocities, and thus more mafic compositions, than average continental crust, implying that significant modifications would be required for this arc to be a suitable building block for continental crust. Lateral variations in average crustal velocity (below 10 km) roughly correspond to trends in major element geochemistry of primitive (Mg # > 0.6) lavas. The highest lower-crustal velocities (and presumably most mafic material) are detected in the center of an arc segment, between Unmak and Unalaska Islands, implying that arc segmentation exerts control over crustal composition. |
format |
Article in Journal/Newspaper |
author |
Shillington, Donna J. Van Avendonk, Harm J.A. Holbrook, W. Steven Keleman, Peter B. Hornbach, Matthew J. |
spellingShingle |
Shillington, Donna J. Van Avendonk, Harm J.A. Holbrook, W. Steven Keleman, Peter B. Hornbach, Matthew J. Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data |
author_facet |
Shillington, Donna J. Van Avendonk, Harm J.A. Holbrook, W. Steven Keleman, Peter B. Hornbach, Matthew J. |
author_sort |
Shillington, Donna J. |
title |
Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data |
title_short |
Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data |
title_full |
Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data |
title_fullStr |
Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data |
title_full_unstemmed |
Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data |
title_sort |
composition and structure of the central aleutian island arc from arc-parallel wide-angle seismic data |
publishDate |
2004 |
url |
https://eprints.soton.ac.uk/15819/ |
genre |
Aleutian Island |
genre_facet |
Aleutian Island |
op_relation |
Shillington, Donna J., Van Avendonk, Harm J.A., Holbrook, W. Steven, Keleman, Peter B. and Hornbach, Matthew J. (2004) Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data. Geochemistry, Geophysics, Geosystems, 5 (10), 1-32. (doi:10.1029/2004GC000715 <http://dx.doi.org/10.1029/2004GC000715>). |
op_doi |
https://doi.org/10.1029/2004GC000715 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
5 |
container_issue |
10 |
container_start_page |
n/a |
op_container_end_page |
n/a |
_version_ |
1772809727232704512 |