Controlling factor of incoming plate hydration at the north-western Pacific margin

Gou Fujie,Tsutomu Takahashi,Yuka Kaiho,Yojiro Yamamoto,Tomoaki Yamada,Shuichi Kodaira,Seiichi Miura

doi:10.1038/s41467-018-06320-z

Gou Fujie, Tsutomu Takahashi + Show 5 more

Open Access

https://doi.org/10.1038/s41467-018-06320-z

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Abstract

Hydration of the subducting oceanic plate determines the amount of water transported from Earth’s surface into its interior, and plate bending-related faulting (bend faulting) just prior to subduction is considered to promote hydration. Bend faulting shows significant spatial variation, but its contribution to hydration is still poorly understood. Here we present the results of controlled-source seismic surveys around the junction of the Japan and Kuril trenches. We found structural changes caused by bend faulting before subduction differed distinctly between both trenches and were well correlated with plate hydration after subduction, suggesting the bend faulting controls spatial variations in plate hydration. Differences in bend faulting are closely related to the angle between the current trench and the ancient spreading ridge, and the hydration is more extensive where this trench-ridge angle is oblique in the study area. Thus, we propose this angle is a major factor controlling plate hydration.

Highlights

Hydration of the subducting oceanic plate determines the amount of water transported from Earth’s surface into its interior, and plate bending-related faulting just prior to subduction is considered to promote hydration
Dehydration occurring within the subducting oceanic plate induces intra-slab intermediate-depth earthquakes, and the expelled water leads to arc magmatism, promotes metamorphism, lowers the slab temperature, and affects interplate coupling[1,2]
Unlike hydrothermal circulation near the spreading ridge, which is confined to the oceanic crust, bend faulting near the subduction trench can potentially cut across the entire crust and reach to the upper mantle

Summary

Introduction

Hydration of the subducting oceanic plate determines the amount of water transported from Earth’s surface into its interior, and plate bending-related faulting (bend faulting) just prior to subduction is considered to promote hydration. Differences in bend faulting are closely related to the angle between the current trench and the ancient spreading ridge, and the hydration is more extensive where this trench-ridge angle is oblique in the study area We propose this angle is a major factor controlling plate hydration. In the Kuril Trench, the throw is less than half (at most 400 m), and the spacing is much less (roughly 5 km) (Fig. 2d) These differences make this trench junction a good place to investigate the contribution of bend faulting and its spatial variations to plate hydration

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