Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth

Ronit Kessel*, Max W. Schmidt, Peter Ulmer, Thomas Pettke

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1144 Scopus citations

Abstract

Fluids and melts liberated from subducting oceanic crust recycle lithophile elements back into the mantle wedge, facilitate melting and ultimately lead to prolific subduction-zone arc volcanism. The nature and composition of the mobile phases generated in the subducting slab at high pressures have, however, remained largely unknown. Here we report direct LA-ICPMS measurements of the composition of fluids and melts equilibrated with a basaltic eclogite at pressures equivalent to depths in the Earth of 120-180 km and temperatures of 700-1,200°C. The resultant liquid/mineral partition coefficients constrain the recycling rates of key elements. The dichotomy of dehydration versus melting at 120 km depth is expressed through contrasting behaviour of many trace elements (U/Th, Sr, Ba, Be and the light rare-earth elements). At pressures equivalent to 180 km depth, however, a supercritical liquid with melt-like solubilities for the investigated trace elements is observed, even at low temperatures. This mobilizes most of the key trace elements (except the heavy rare-earth elements, Y and Sc) and thus limits fluid-phase transfer of geochemical signatures in subduction zones to pressures less than 6 GPa.

Original languageAmerican English
Pages (from-to)724-727
Number of pages4
JournalNature
Volume437
Issue number7059
DOIs
StatePublished - 29 Sep 2005

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