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Mantle wedge control on back-arc crustal accretion

Mantle wedge control on back-arc crustal accretion At mid-ocean ridges, plate separation leads to upward advection and pressure-release partial melting of fertile mantle material; the melt is then extracted to the spreading centre and the residual depleted mantle flows horizontally away 1 . In back-arc basins, the subducting slab is an important control on the pattern of mantle advection and melt extraction, as well as on compositional and fluid gradients 2 . Modelling studies 3 predict significant mantle wedge effects on back-arc spreading processes. Here we show that various spreading centres in the Lau back-arc basin exhibit enhanced, diminished or normal magma supply, which correlates with distance from the arc volcanic front but not with spreading rate. To explain this correlation we propose that depleted upper-mantle material, generated by melt extraction in the mantle wedge, is overturned and re-introduced beneath the back-arc basin by subduction-induced corner flow. The spreading centres experience enhanced melt delivery near the volcanic front, diminished melting within the overturned depleted mantle farther from the corner and normal melting conditions in undepleted mantle farther away. Our model explains fundamental differences in crustal accretion variables between back-arc and mid-ocean settings. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Springer Journals

Mantle wedge control on back-arc crustal accretion

Martinez, Fernando; Taylor, Brian
Nature , Volume 416 (6879) – Mar 28, 2002
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References (32)

Publisher
Springer Journals
Copyright
Copyright © 2002 by Nature Publishing Group
Subject
Science, Humanities and Social Sciences, multidisciplinary; Science, Humanities and Social Sciences, multidisciplinary; Science, multidisciplinary
ISSN
0028-0836
eISSN
1476-4687
DOI
10.1038/416417a
Publisher site
See Article on Publisher Site

Abstract

At mid-ocean ridges, plate separation leads to upward advection and pressure-release partial melting of fertile mantle material; the melt is then extracted to the spreading centre and the residual depleted mantle flows horizontally away 1 . In back-arc basins, the subducting slab is an important control on the pattern of mantle advection and melt extraction, as well as on compositional and fluid gradients 2 . Modelling studies 3 predict significant mantle wedge effects on back-arc spreading processes. Here we show that various spreading centres in the Lau back-arc basin exhibit enhanced, diminished or normal magma supply, which correlates with distance from the arc volcanic front but not with spreading rate. To explain this correlation we propose that depleted upper-mantle material, generated by melt extraction in the mantle wedge, is overturned and re-introduced beneath the back-arc basin by subduction-induced corner flow. The spreading centres experience enhanced melt delivery near the volcanic front, diminished melting within the overturned depleted mantle farther from the corner and normal melting conditions in undepleted mantle farther away. Our model explains fundamental differences in crustal accretion variables between back-arc and mid-ocean settings.

Journal

Nature – Springer Journals

Published: Mar 28, 2002

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