Progressive sub-arc mantle oxidation modulated by sediment melt.
basic_science · Level V
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- Record sourced from PubMed, PMID 41931617.
- Also identified by DOI 10.1126/sciadv.aeb9023.
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Abstract
The redox state of the sub-arc mantle beneath volcanic arcs is typically oxidized but exhibits substantial variability. Previous studies proposed that the incorporation of slab components alters both arc magma compositions and sub-arc mantle redox state, whereas the dominant component remains debated. Here, by compiling global Cenozoic primitive arc basalt and olivine-hosted melt inclusion data, we show that sediment melt dominated by terrigenous origin plays the controlling role. Progressive influx of sediment melts into the sub-arc mantle results in gradual enrichment of potassium oxide and most incompatible elements in arc magmas. Increases in potassium oxide content in primitive magmas also correlates with rising oxygen fugacity (<i>f</i>o<sub>2</sub>) values, highlighting the strong oxidizing potential of sediment melt. The high-potassium oxide, high-<i>f</i>o<sub>2</sub> arc magmas spatially correlate with the distribution of Cenozoic porphyry copper-gold deposits, showing that the sediment melt influx not only elevates the sub-arc mantle <i>f</i>o<sub>2</sub> but also enhances the metallogenetic potential for porphyry deposits.