Mobilization of isotopically heavy sulfur during serpentinite subduction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39110792.
- Also identified by DOI 10.1126/sciadv.adn0641 and PMC identifier 11305377.
- 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
Primitive arc magmas are more oxidized and enriched in sulfur-34 (<sup>34</sup>S) compared to mid-ocean ridge basalts. These findings have been linked to the addition of slab-derived volatiles, particularly sulfate, to arc magmas. However, the oxidation state of sulfur in slab fluids and the mechanisms of sulfur transfer in the slab remain inconclusive. Juxtaposed serpentinite and eclogitic metagabbro from the Voltri Massif (Italy) provide evidence for sulfur mobilization and associated redox processes during infiltration of fluids. Using bulk rock and in situ δ<sup>34</sup>S measurements, combined with thermodynamic calculations, we document the transfer of bisulfide-dominated, <sup>34</sup>S-enriched fluids in equilibrium with serpentinite into adjacent metagabbro. We argue that the process documented in this study is pervasive along the subduction interface and infer that subsequent melting of these reacted slab-mantle interface rocks could produce melts that display the characteristic oxygen fugacity and sulfur isotope signatures of arc magmas worldwide.