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Stability of hydrous phases in subducting oceanic crust

J. Liu·S.R. Bohlen·W. G. Ernst
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Abstract

Experiments in the basalt-H 2 O 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 H 2 O occurs as a free fluid or in silicate melt co-existing with an anhydrous eclogite assemblage. In contrast, about 0.5 wt% of H 2 O 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, H 2 O stored in hydrated low-potassium, metabasaltic layers cannot be subducted to depths greater than 100 km, then released to generate arc magma.

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BibTeXRIS

J. Liu, S.R. Bohlen, W. G. Ernst. 1996. Stability of hydrous phases in subducting oceanic crust. https://doi.org/10.1016/0012-821x(96)00130-6

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