Saline aqueous fluid circulation in mantle wedge inferred from olivine wetting properties

Yongsheng Huang,Catherine Mccammon,Takayuki Nakatani,Michihiko Nakamura

doi:10.1038/s41467-019-13513-7

Yongsheng Huang, Catherine Mccammon + Show 2 more

Open Access

https://doi.org/10.1038/s41467-019-13513-7

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Journal: Nature Communications	Publication Date: Dec 1, 2019
Citations: 18	License type: open-access

Affiliation: University of Bayreuth, Tohoku University

Abstract

Recently, high electrical conductors have been detected beneath some fore-arcs and are believed to store voluminous slab-derived fluids. This implies that the for-arc mantle wedge is permeable for aqueous fluids. Here, we precisely determine the dihedral (wetting) angle in an olivine–NaCl–H2O system at fore-arc mantle conditions to assess the effect of salinity of subduction-zone fluids on the fluid connectivity. We find that NaCl significantly decreases the dihedral angle to below 60° in all investigated conditions at concentrations above 5 wt% and, importantly, even at 1 wt% at 2 GPa. Our results show that slab-released fluid forms an interconnected network at relatively shallow depths of ~80 km and can partly reach the fore-arc crust without causing wet-melting and serpentinization of the mantle. Fluid transport through this permeable window of mantle wedge accounts for the location of the high electrical conductivity anomalies detected in fore-arc regions.

Highlights

High electrical conductors have been detected beneath some fore-arcs and are believed to store voluminous slab-derived fluids
The released aqueous fluid can control the partial melting of the mantle wedge because the presence of aqueous fluid effectively decreases the peridotite solidus temperature, which leads to the formation of arc magma[8,9,10,11]
Water mass balance and geophysical observations, have indicated that a water output flux other than volcanic emission should exist in subduction zones

Summary

Introduction

High electrical conductors have been detected beneath some fore-arcs and are believed to store voluminous slab-derived fluids. Watson and Brenan[28] investigated θ between olivine and aqueous fluid with 27.5 wt% NaCl at 1 GPa and 1000 °C, further systematic studies are required to reveal the pressure and temperature dependence of θ in a wide range of NaCl concentrations under mantle wedge conditions.

Results

Conclusion