Skip to main content

Research Repository

Advanced Search

Spatial variation of subduction zone fluids during progressive subduction: Insights from Serpentinite Mud Volcanoes

Menzies, Catriona D.; Price, Roy E.; Ryan, Jeffrey; Sissmann, Olivier; Takai, Ken; Wheat, C. Geoffrey

Spatial variation of subduction zone fluids during progressive subduction: Insights from Serpentinite Mud Volcanoes Thumbnail


Authors

Roy E. Price

Jeffrey Ryan

Olivier Sissmann

Ken Takai

C. Geoffrey Wheat



Abstract

Geological processes at subduction zones control seismicity, plutonism and volcanism, and geochemical cycling between the oceans, crust, and mantle. The down-going plate experiences metamorphism, and the associated dehydration and fluid flow alters the physical properties of the plate interface and mantle wedge, as well as controlling the composition of material descending into the mantle. Any direct study of slab evolution during subduction is inhibited by the prohibitive depths at which these processes occur. To examine these processes we use serpentinite mud volcanoes in the Mariana forearc, that permit sampling of serpentinite materials and their pore waters that ascend from the subduction channel. We present new pore water chemical data from the summit and flanks of three serpentinite mud volcanoes that were drilled during International Ocean Discovery Program Expedition 366 which are reflective of reactions within the crust and mantle during the early, shallow (<20 km) stages of subduction. We show, via thermodynamic modelling, that our new data on the evolution of pore water chemical compositions reflect mineralogical characteristics of a predominately basaltic source from the downgoing Pacific Plate. However, a component from sedimentary sources is likely, especially for those mud volcanoes near the trench. Other potential slab-derived constituents, such as lithospheric serpentinite, carbonate-rich sediments, or seamount basalts with an intraplate geochemical character, are not required to explain our results. Our results indicate that with progressive subduction the lawsonite-epidote mineral transformation boundary at ∼250 °C may help drive slab carbonate destabilisation, despite its apparent thermodynamic stability at such temperatures and projected pressures (∼300 °C and ∼0.6 GPa). New dissolved gas data also point to primary thermodynamic controls over methane/ethane production within the subduction channel as depths-to-slab increase. Our findings provide direct evidence for the progressive mineralogical and chemical evolution of a subducting oceanic plate, which liberates a progressively evolving fluid phase into the subduction channel.

Citation

Menzies, C. D., Price, R. E., Ryan, J., Sissmann, O., Takai, K., & Wheat, C. G. (2022). Spatial variation of subduction zone fluids during progressive subduction: Insights from Serpentinite Mud Volcanoes. Geochimica et Cosmochimica Acta, 319, 118-134. https://doi.org/10.1016/j.gca.2021.10.030

Journal Article Type Article
Acceptance Date Oct 29, 2021
Online Publication Date Nov 2, 2021
Publication Date Feb 15, 2022
Deposit Date Dec 17, 2021
Publicly Available Date Dec 17, 2021
Journal Geochimica et Cosmochimica Acta
Print ISSN 0016-7037
Electronic ISSN 1872-9533
Publisher Meteoritical Society
Peer Reviewed Peer Reviewed
Volume 319
Pages 118-134
DOI https://doi.org/10.1016/j.gca.2021.10.030
Public URL https://durham-repository.worktribe.com/output/1220179

Files






You might also like



Downloadable Citations