Mantle dynamics, element recycling, and magma genesis beneath the Kermadec Arc-Havre Trough.

Haase, Karsten, Worthington, Timothy, Stoffers, Peter, Garbe-Schönberg, D. and Wright, I. (2002) Mantle dynamics, element recycling, and magma genesis beneath the Kermadec Arc-Havre Trough. Geochemistry, Geophysics, Geosystems, 3 . DOI 107110.1029/2002gc000335.

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Abstract

[1] New geochemical and isotopic data are presented for lavas from three sites in the Havre Trough-Lau Basin back arc and six volcanoes along the Kermadec arc. The back arc basalts range from MORB-like to arc-like in composition and contain a variable contribution from the underlying slab. The least contaminated MORB-like back arc lavas from 24degrees-29degreesS are low degree partial melts of a source with Pacific MORB isotopic characteristics. A transition occurs at 30 S between the strongly depleted northern Kermadec (and Tonga) arc lavas and the mildly depleted southern Kermadec arc lavas. This transition does not correlate with changes in the back arc extension rate or width but may reflect inhibited mantle wedge replenishment behind the shallower-dipping northern Kermadec- Tonga slab. Northern Kermadec lavas require mixing between two components: (1) depleted Havre Trough mantle and (2) fluid derived from altered MORB crust with a slight input of sediment lead. Inter-volcano differences in fluid compositions probably reflect local variations on the subducting slab rather than mineralogical variation in the mantle wedge. Southern Kermadec lavas require an additional component: (3) Pacific sediment melt. This sediment melt is only detected where the subduction rate is <7 cm/year, and requires thermal heating of the slab to >650degreesC before passing through the sub-arc melt generation zone.

Document Type: Article
Keywords: volcanic arc mantle depletion element recycling geochemistry Sr-Nd-Pb isotopes Tonga-Kermadec arc Havre Trough southern lau basin subduction-zone sw pacific island-arc trace-elements oceanic-crust isotope geochemistry southwest pacific continental-crust tonga trench
Research affiliation: Kiel University
DOI etc.: 107110.1029/2002gc000335
ISSN: 1525-2027
Date Deposited: 02 Feb 2012 07:02
Last Modified: 08 Oct 2012 10:36
URI: http://oceanrep.geomar.de/id/eprint/16239

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