Zinc isotope evidence for sulfate-rich fluid transfer across subduction zones.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 27982033.
- Also identified by DOI 10.1038/ncomms13794 and PMC identifier 5171646.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Subduction zones modulate the chemical evolution of the Earth's mantle. Water and volatile elements in the slab are released as fluids into the mantle wedge and this process is widely considered to result in the oxidation of the sub-arc mantle. However, the chemical composition and speciation of these fluids, which is critical for the mobility of economically important elements, remain poorly constrained. Sulfur has the potential to act both as oxidizing agent and transport medium. Here we use zinc stable isotopes (δ<sup>66</sup>Zn) in subducted Alpine serpentinites to decipher the chemical properties of slab-derived fluids. We show that the progressive decrease in δ<sup>66</sup>Zn with metamorphic grade is correlated with a decrease in sulfur content. As existing theoretical work predicts that Zn-SO<sub>4</sub><sup>2-</sup> complexes preferentially incorporate heavy δ<sup>66</sup>Zn, our results provide strong evidence for the release of oxidized, sulfate-rich, slab serpentinite-derived fluids to the mantle wedge.