50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...
50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...
50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...
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5 Dept. of Mineral Sciences, Smithsonian<br />
Institution, Washington, USA.<br />
6 Research School of Earth Sciences, Australian<br />
National University, Canberra.<br />
(richardw*jamstec.go.jp)<br />
Convergent margins, where oceanic lithosphere is<br />
subducted back into the mantle, form the key<br />
interface for large–scale element recycling between<br />
ocean, crust, mantle, and atmosphere. Recycling of<br />
elements in occurs as sediments and altered oceanic<br />
crust (AOC) in the subducting slab dehydrate<br />
and/or melt, releasing water and mobile elements<br />
into the overlying mantle wedge, initiating melting<br />
and the generation of arc magmatism. The<br />
composition of arc magmas reflects these multiple<br />
sources and is further complicated by assimilation<br />
of arc crust and hydrothermal fluids and brines as<br />
the magma ascends. Deconvolving the origin and<br />
transport mechanism of slab fluids and melts in<br />
subduction zones requires identifying tracer<br />
elements specific to a source and/or mechanism.<br />
Fluid-mobile elements such as Cl, Ba, and Pb<br />
provide the potential to investigate the composition<br />
and source of aqueous fluids derived from the<br />
subducting slab in arc systems. In the southern<br />
Kermadec arc – Havre Trough (KAHT) pillowbasalt<br />
glasses have water (~1.5 wt.%) and carbon<br />
(