Oxidation state of subarc mantle
MetadataShow full item record
The subarc mantle is a primary control on the composition of arc magmas and the formation of arc-related ore deposits. Elevated ferric iron contents in arc lavas have been interpreted as a record of subarc mantle that is oxidized relative to mid-oceanic ridge basalt (MORB), but this conclusion is controversial. Measurements of spinel compositions in primitive arc lavas imply an arc magma source 1–4 log units more oxidized than MORB and ocean island basalts analyzed using the same technique. Samples from seven arcs show a significant correlation (P < 0.0005) between redox budget, subduction zone convergence rate, and subduction zone age. These results support the notion of oxidized arc lavas in the mantle source zone, but resolution of contradictory evidence regarding subarc mantle redox state requires further work.
Showing items related by title, author, creator and subject.
Evans, Katy; Tomkins, A. (2011)A number of lines of evidence point to a causal link between oxidised slab-derived fluids, oxidised sub-arc mantle, and the formation of economic concentrations of metals such as Cu and Au that require oxidised magmas. ...
Evans, Katy; Reddy, Steven; Tomkins, A.; Crossley, Rosalind; Frost, B. (2017)Magnetite breakdown during subduction of serpentinised ultramafic rocks may produce oxidised fluids that oxidise the deep Earth and/or the sub-arc mantle, either via direct transport of ferric iron, or via redox reactions ...
Tomkins, A.; Evans, Katy (2015)Liberation of fluids during subduction of oceanic crust is thought to transfer sulfur into the overlying sub-arc mantle. However, despite the importance of sulfur cycling through magmatic arcs to climate change, magma ...