Serpentinite-derived slab fluids control the oxidation state of the subarc mantle.
Serpentinite-derived slab fluids control the oxidation state of the subarc mantle.
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DOI：
10.1126/sciadv.abj2515
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发表时间：
2021-11-26
期刊：
影响因子：
13.6
通讯作者：
Klein F
中科院分区：
文献类型：
--
作者：
Zhang Y;Gazel E;Gaetani GA;Klein F
合并不同量的氧化板流体导致全球不均匀的亚弧地幔的氧化状态。最近的地球化学证据证实了弧岩浆的氧化性质，但调节弧下地幔氧化还原状态的基本过程仍有待确定。利用B同位素和B/Nb作为流体指标，建立了蛇纹岩±蚀变洋壳（AOC）脱水形成的深俯冲相关流体与岩浆演化过程中Cu富集和V/Y B指示的弧岩浆氧化性质之间的联系。我们的研究结果表明，弧岩浆来自源区的蛇纹岩（±AOC）流体成分的影响记录较高的氧逸度。这一组成部分纳入弧下地幔的俯冲系统的热力学条件和几何控制。我们的研究结果表明，弧下地幔的氧化还原状态是不均匀的全球性：原始弧岩浆与平坦，温暖的俯冲整体氧化程度低于陡峭，寒冷的俯冲带。
Incorporation of variable amounts of oxidizing slab fluids leads to globally heterogeneous oxidation state of the subarc mantle. Recent geochemical evidence confirms the oxidized nature of arc magmas, but the underlying processes that regulate the redox state of the subarc mantle remain yet to be determined. We established a link between deep subduction-related fluids derived from dehydration of serpentinite ± altered oceanic crust (AOC) using B isotopes and B/Nb as fluid proxies, and the oxidized nature of arc magmas as indicated by Cu enrichment during magma evolution and V/Yb. Our results suggest that arc magmas derived from source regions influenced by a greater serpentinite (±AOC) fluid component record higher oxygen fugacity. The incorporation of this component into the subarc mantle is controlled by the subduction system’s thermodynamic conditions and geometry. Our results suggest that the redox state of the subarc mantle is not homogeneous globally: Primitive arc magmas associated with flat, warm subduction are less oxidized overall than those generated in steep, cold subduction zones.
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