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Iron isotopic evidence for convective resurfacing of recycled arc‐front mantle beneath back‐arc basins
Author(s) -
Nebel O.,
Arculus R. J.,
Sossi P. A.,
Jenner F. E.,
Whan T. H. E.
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2013gl057976
Subject(s) - geology , mantle (geology) , arc (geometry) , convection , geophysics , front (military) , meteorology , oceanography , geometry , mathematics , physics
Geophysical observations suggest sub‐arc convective flow transports melt‐exhausted and metasomatized wedge mantle into deeper mantle regions. Reciprocally, asthenospheric, fertile mantle may supply back‐arc ridges distal to the trench by shallow, lateral mantle ingress, insinuating initial wedge mantle depletion in its back‐arc region. Here we show that light Fe isotope compositions of the Central Lau Spreading Centre located in the Lau back‐arc basin on the farside of the Tonga‐Kermadec arc are indicative for derivation from a modified arc‐front mantle with elemental and Nd‐isotopic memory of former slab fluid addition. We propose that this shallow wedge material has been transported from the sub‐arc mantle to the back‐arc either convectively or in a buoyant diapir. This implies that melt‐depleted mantle in subduction zones is, at least in parts, recycled in a resurfacing loop. This can explain the depletion in back‐arc regions, and the progressively depleted nature of island arc sources in maturing arc systems.