Constraints on the composition of the Aleutian arc lower crust from
Determining the bulk composition of island arc lower crust is essential for distinguishing between competing models for arc magmatism and assessing the stability of arc lower crust. We present new constraints on the composition of high P-wave velocity (VP = 7.3–7.6 km/s) lower crust of the Aleutian...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | en_US |
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American Geophysical Union
2014
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| Online Access: | http://hdl.handle.net/1721.1/87702 https://orcid.org/0000-0003-2402-3736 |
| _version_ | 1826195788609355776 |
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| author | Shillington, Donna J. Van Avendonk, Harm J. A. Behn, Mark Kelemen, Peter B. Jagoutz, Oliver E |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Shillington, Donna J. Van Avendonk, Harm J. A. Behn, Mark Kelemen, Peter B. Jagoutz, Oliver E |
| author_sort | Shillington, Donna J. |
| collection | MIT |
| description | Determining the bulk composition of island arc lower crust is essential for distinguishing between competing models for arc magmatism and assessing the stability of arc lower crust. We present new constraints on the composition of high P-wave velocity (VP = 7.3–7.6 km/s) lower crust of the Aleutian arc from best-fitting average lower crustal VP/VS ratio using sparse converted S-waves from an along-arc refraction profile. We find a low VP/VS of ~1.7–1.75. Using petrologic modeling, we show that no single composition is likely to explain the combination of high VP and low VP/VS. Our preferred explanation is a combination of clinopyroxenite (~50–70%) and alpha-quartz bearing gabbros (~30–50%). This is consistent with Aleutian xenoliths and lower crustal rocks in obducted arcs, and implies that ~30–40% of the full Aleutian crust comprises ultramafic cumulates. These results also suggest that small amounts of quartz can exert a strong influence on VP/VS in arc crust. |
| first_indexed | 2024-09-23T10:15:27Z |
| format | Article |
| id | mit-1721.1/87702 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:15:27Z |
| publishDate | 2014 |
| publisher | American Geophysical Union |
| record_format | dspace |
| spelling | mit-1721.1/877022024-05-15T03:22:15Z Constraints on the composition of the Aleutian arc lower crust from Shillington, Donna J. Van Avendonk, Harm J. A. Behn, Mark Kelemen, Peter B. Jagoutz, Oliver E Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Jagoutz, Oliver E. Jagoutz, Oliver E. Determining the bulk composition of island arc lower crust is essential for distinguishing between competing models for arc magmatism and assessing the stability of arc lower crust. We present new constraints on the composition of high P-wave velocity (VP = 7.3–7.6 km/s) lower crust of the Aleutian arc from best-fitting average lower crustal VP/VS ratio using sparse converted S-waves from an along-arc refraction profile. We find a low VP/VS of ~1.7–1.75. Using petrologic modeling, we show that no single composition is likely to explain the combination of high VP and low VP/VS. Our preferred explanation is a combination of clinopyroxenite (~50–70%) and alpha-quartz bearing gabbros (~30–50%). This is consistent with Aleutian xenoliths and lower crustal rocks in obducted arcs, and implies that ~30–40% of the full Aleutian crust comprises ultramafic cumulates. These results also suggest that small amounts of quartz can exert a strong influence on VP/VS in arc crust. Columbia University (Arthur D. Storke Chair) National Science Foundation (U.S.) (NSF grant OCE 0520378) National Science Foundation (U.S.) (NSF grant OCE 0728077) National Science Foundation (U.S.) (NSF grant EAR 0727013) 2014-06-09T16:08:04Z 2014-06-09T16:08:04Z 2013-06 2013-03 Article http://purl.org/eprint/type/JournalArticle 00948276 http://hdl.handle.net/1721.1/87702 Shillington, Donna J., Harm J. A. Van Avendonk, Mark D. Behn, Peter B. Kelemen, and Oliver Jagoutz. “ Constraints on the Composition of the Aleutian Arc Lower Crust from V P / V S .” Geophys. Res. Lett. 40, no. 11 (June 16, 2013): 2579–2584. https://orcid.org/0000-0003-2402-3736 en_US http://dx.doi.org/10.1002/grl.50375 Geophysical Research Letters Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Geophysical Union Jagoutz via Michael Noga |
| spellingShingle | Shillington, Donna J. Van Avendonk, Harm J. A. Behn, Mark Kelemen, Peter B. Jagoutz, Oliver E Constraints on the composition of the Aleutian arc lower crust from |
| title | Constraints on the composition of the Aleutian arc lower crust from |
| title_full | Constraints on the composition of the Aleutian arc lower crust from |
| title_fullStr | Constraints on the composition of the Aleutian arc lower crust from |
| title_full_unstemmed | Constraints on the composition of the Aleutian arc lower crust from |
| title_short | Constraints on the composition of the Aleutian arc lower crust from |
| title_sort | constraints on the composition of the aleutian arc lower crust from |
| url | http://hdl.handle.net/1721.1/87702 https://orcid.org/0000-0003-2402-3736 |
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