Subducting serpentinites release reduced, not oxidized, aqueous fluids

Piccoli, F.; Hermann, J.; Pettke, T.; Connolly, J.A.D.; Kempf, E. D.; Vieira Duarte, J. F. (2019). Subducting serpentinites release reduced, not oxidized, aqueous fluids. Scientific reports, 9(1) Springer Nature 10.1038/s41598-019-55944-8

[img]
Preview
Text (Gold Open Access)
Piccoli-et-al_Nat-Sci-Rep_2019.pdf - Published Version
Available under License Creative Commons: Attribution (CC-BY).

Download (2MB) | Preview

The observation that primitive arc magmas are more oxidized than mid-ocean-ridge basalts has led to the paradigm that slab-derived fluids carry SO2 and CO2 that metasomatize and oxidize the subarc mantle wedge. We combine petrography and thermodynamic modelling to quantify the oxygen fugacity (fO2) and speciation of the fluids generated by serpentinite dehydration during subduction. Silicate-magnetite assemblages maintain fO2 conditions similar to the quartz-fayalite-magnetite (QFM) buffer at fore-arc conditions. Sulphides are stable under such conditions and aqueous fluids contain minor S. At sub-arc depth, dehydration occurs under more reducing conditions producing aqueous fluids carrying H2S. This finding brings into question current models in which serpentinite-derived fluids are the cause of oxidized arc magmatism and has major implications for the global volatile cycle, as well as for redox processes controlling subduction zone geodynamics.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Rock-Water Interaction

UniBE Contributor:

Piccoli, Francesca; Hermann, Jörg; Pettke, Thomas; Kempf, Elias Dominik and Vieira Duarte, Joana Filipa

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

2045-2322

Publisher:

Springer Nature

Funders:

[UNSPECIFIED] Swiss National Science Foundation grants No. 200021_172688 to T.P.
[UNSPECIFIED] Swiss National Science Foundation grants No. 200021_169062 to J.H.

Language:

English

Submitter:

Thomas Pettke

Date Deposited:

29 Jan 2020 16:09

Last Modified:

12 May 2020 07:58

Publisher DOI:

10.1038/s41598-019-55944-8

BORIS DOI:

10.7892/boris.139262

URI:

https://boris.unibe.ch/id/eprint/139262

Actions (login required)

Edit item Edit item
Provide Feedback