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Titel |
Crustal structure variation along the Lesser Antilles Arc |
VerfasserIn |
David Schlaphorst, Mike Kendall, Jon Blundy, Elena Melekhova, Brian Baptie, Joan Latchman, Marie-Paule Bouin, Steve Tait |
Konferenz |
EGU General Assembly 2014
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 16 (2014) |
Datensatznummer |
250097941
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Publikation (Nr.) |
EGU/EGU2014-13570.pdf |
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Zusammenfassung |
Subduction zones are the major location for the formation of continental crust. Therefore, an
investigation of the crustal and mantle structure variation of these areas helps understanding
the process of continental crust growth.
Here we focus on a seismological investigation of the Lesser Antilles Arc. This island arc
system is built by the relatively slow subduction (~ 2cm-yr) of the North and South
American plates beneath the Caribbean plate.
From the island of Grenada in the South to the Virgin Islands in the North significant
variations in sediment load, petrology and volcanism are observed along the arc. The
abundance of broadband seismic stations on the Lesser Antilles islands in combination with
the abundance of cumulated samples allows for a link between the seismic methods with a
detailed petrological analysis. We use data from three-component broadband stations located
on the individual islands along the arc.
We investigate crustal structure using receiver functions to determine Moho depth and
V P-V S ratio. The ratio gives an idea about the material of the subsurface as well as its
water and its melt contents. We use the extended-time multitaper frequency domain
cross-correlation receiver-function (ETMTRF) by Helffrich (2006) to compute the receiver
functions. This method has the advantage of resistance to noise and gives stable solutions for
the data, despite its large amount of oceanic noise. Our results show clear along-arc crustal
properties. There are regions where the Moho is not very sharp due to a low velocity
contrast.
The real data results are then compared to synthetic receiver functions based on plausible
models. We compute a range of synthetic crustal models and receiver functions based on
petrologic constraints from cumulates. The seismic velocities are obtained from experimental
data using different temperatures and pressures to simulate different depths. The initial water
content was also varied to model dry and wet slab conditions. Our results suggest that
receiver functions are very sensitive to the amount of water in lower-crustal assemblages in
arc settings. |
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