biostudies-literatureUnknown8(12)Zhao SYArc volcanics are more oxidized than mid-ocean ridge basalts (MORB), but it is debated whether this is a mantle feature or a result of magmatic evolution. Copper, a sulfur-loving element, has been used to trace the behavior of redox-sensitive sulfur during mantle melting and infer similar redox states of sub-arc and sub-ridge mantle. Previous studies, however, neglected elevated sulfur contents in the sub-arc mantle, leading to underestimation of oxygen fugacities, and did not recognize systematic Cu variations in arc volcanics. Here, we show that the Cu/Zr ratio is a sensitive indicator that responds to sulfur content, oxygen fugacity, and extent of melting of the mantle. Because of higher mantle S contents, Cu systematics of arc magmas require one log unit higher oxygen fugacities of subScience advanceseabk0718https://www.ebi.ac.uk/biostudies/studies/S-EPMC8942352biostudies-literatureOxidized primary arc magmas: Constraints from Cu/Zr systematics in global arc volcanics.PMC8942352Zhao TPLangmuir CHZhao SYYang AYfalseOxidized primary arc magmas: Constraints from Cu/Zr systematics in global arc volcanics.Arc volcanics are more oxidized than mid-ocean ridge basalts (MORB), but it is debated whether this is a mantle feature or a result of magmatic evolution. Copper, a sulfur-loving element, has been used to trace the behavior of redox-sensitive sulfur during mantle melting and infer similar redox states of sub-arc and sub-ridge mantle. Previous studies, however, neglected elevated sulfur contents in the sub-arc mantle, leading to underestimation of oxygen fugacities, and did not recognize systematic Cu variations in arc volcanics. Here, we show that the Cu/Zr ratio is a sensitive indicator that responds to sulfur content, oxygen fugacity, and extent of melting of the mantle. Because of higher mantle S contents, Cu systematics of arc magmas require one log unit higher oxygen fugacities of sub2022-01-01T00:00:00Z2022 Mar2025-04-04T19:10:29.7Z2025-04-04T19:10:29.7ZS-EPMC89423523531999510.1126/sciadv.abk0718