Focused fluid transfer through the mantle above subduction zones

Pirard, Cassian, and Hermann, Joerg (2015) Focused fluid transfer through the mantle above subduction zones. Geology, 43 (10). pp. 915-918.

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Abstract

Volcanic arcs above subduction zones are enriched in volatiles and fluid-mobile elements with respect to mid-oceanic ridge basalts. There is general consensus that this particular subduction zone signature is generated by fluid-induced extraction of these elements from subducted oceanic crust and its sedimentary cover. However, how these fluids are transferred through the mantle wedge to the locus of partial melting and what modification the fluids will experience is unresolved. Here we investigate the interaction of slab fluids with the mantle wedge through a series of high-pressure experiments. We explore two end-member processes of focused and porous reactive flow of hydrous slab melts through the mantle. Transfer by porous flow leads to the formation of hydrous minerals that sequester fluid-mobile elements and residual fluids characterized by trace element patterns inconsistent with typical arc lavas. In contrast, no hydrous minerals are formed in the reaction zone of experiments mimicking focused flow, and the typical trace element signature acquired during fluid extraction from the slab is preserved, indicating that this is an efficient process for element transfer through the mantle wedge.

Item ID: 41793
Item Type: Article (Research - C1)
ISSN: 1943-2682
Funders: Australian Research Council (ARC)
Date Deposited: 08 Dec 2015 16:44
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040304 Igneous and Metamorphic Petrology @ 60%
04 EARTH SCIENCES > 0402 Geochemistry > 040202 Inorganic Geochemistry @ 40%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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