Stability of hydrous phases in subducting oceanic crust

Earth and Planetary Science Letters
By: , and 

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Abstract

Experiments in the basalt-H2O system at 600–950°C and 0.8–3.0 GPa, demonstrate that breakdown of amphibole represents the final dehydration of subducting oceanic tholeiite at T≥650°C; the dehydration H2O occurs as a free fluid or in silicate melt co-existing with an anhydrous eclogite assemblage. In contrast, about 0.5 wt% of H2O is stored in lawsonite at 600°C, 3.0 GPa. Our results suggest that slab melting occurs at depths shallower than 60 km for subducting young oceanic crust; along a subduction zone with an average thermal gradient higher than 7°C/km, H2O stored in hydrated low-potassium, metabasaltic layers cannot be subducted to depths greater than 100 km, then released to generate arc magma.

Publication type Article
Publication Subtype Journal Article
Title Stability of hydrous phases in subducting oceanic crust
Series title Earth and Planetary Science Letters
DOI 10.1016/0012-821X(96)00130-6
Volume 143
Issue 1-4
Year Published 1996
Language English
Publisher Elsevier
Description 11 p.
First page 161
Last page 171
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