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dc.contributor.authorShillington, Donna J.  Concept link
dc.contributor.authorVan Avendonk, Harm J. A.  Concept link
dc.contributor.authorHolbrook, W. Steven  Concept link
dc.contributor.authorKelemen, Peter B.  Concept link
dc.contributor.authorHornbach, Matthew J.  Concept link
dc.date.accessioned2006-01-26T16:07:37Z
dc.date.available2006-01-26T16:07:37Z
dc.date.issued2004-10-21
dc.identifier.citationGeochemistry Geophysics Geosystems 5 (2004): Q10006en
dc.identifier.urihttps://hdl.handle.net/1912/459
dc.descriptionAuthor Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 5 (2004): Q10006, doi:10.1029/2004GC000715.
dc.description.abstractNew 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.en
dc.description.sponsorshipFunding for this work was provided by the University of Wyoming Graduate School.en
dc.format.extent7230986 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen
dc.publisherAmerican Geophysical Unionen
dc.relation.urihttps://doi.org/10.1029/2004GC000715
dc.subjectContinental crusten
dc.subjectCrustal geophysicsen
dc.subjectIsland arcen
dc.subjectMajor element geochemistryen
dc.titleComposition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic dataen
dc.typeArticleen
dc.identifier.doi10.1029/2004GC000715


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