Focused fluid flow during subduction: Oxygen isotope data from high-pressure ophiolites of the western Alps

摘要: Abstract During subduction, hydrothermally altered oceanic crust undergoes extensive dehydration. The water released migrates upwards and may escape along the slab-mantle interface, or continue rising to hydrate mantle overlying subducting slab. Oxygen isotope ratios from eclogitic ophiolites of western Alps correlate closely with lithology. Samples little-altered basalt as a protolith have δ 18 O values 5.1–6.0‰. Material representing low-temperature alteration zone rocks 5.9–6.6‰ orginating in high-temperature zones 4.6–5.3‰. These isotopic approach those ocean unmetamorphosed ophiolites. data suggest that Alpine not experienced significant fluid flow during metamorphism, implying subducted is highly focused, probably structurally controlled pathways top then largely although portion it rises further mantle.