Experimentally derived high-pressure cumulates from hydrous arc magmas and consequences for the seismic velocity structure of lower arc crust

Details

Serval ID
serval:BIB_AD7524953E5A
Type
Article: article from journal or magazin.
Collection
Publications
Title
Experimentally derived high-pressure cumulates from hydrous arc magmas and consequences for the seismic velocity structure of lower arc crust
Journal
Geophysical Research Letters
Author(s)
Muntener O., Ulmer P.
ISSN-L
0094-8276
Publication state
Published
Issued date
2006
Peer-reviewed
Oui
Volume
33
Pages
L21308
Language
english
Abstract
This contribution explores the consequences of experimentally derived ultramafic plutonic rocks for estimates of continental crust composition. The formation of high-pressure cumulates from primitive to evolved hydrous arc magmas was investigated in the range 0.8 - 1.5 GPa and 1350 - 800 degrees C, to provide constraints on solid assemblages that form the roots of island arc crust. At pressures exceeding 0.8 GPa ( 25km), 40 - 60% of ultramafic cumulates are produced to obtain andesite to dacite compositions that are typical for evolved island- arc volcanic and plutonic rocks. Calculated cumulate densities are comparable or higher than upper mantle values, while seismic velocities ( V-p) vary continuously between 7.3 and 8 km/ s, resulting in a broad crust- mantle transition. The Moho represents a plagioclase saturation boundary. Our results are consistent with seismic imaging from continental margins and island arcs, revealing that beneath an active volcanic front a sharp geophysical Moho signature is sometimes absent.
Open Access
Yes
Create date
17/04/2009 23:56
Last modification date
20/08/2019 15:17
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