Geochemical evidence for mélange melting in global arcs.
Geochemical evidence for mélange melting in global arcs.
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DOI：
10.1126/sciadv.1602402
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发表时间：
2017-04
期刊：
影响因子：
13.6
通讯作者：
Marschall HR
中科院分区：
文献类型：
--
作者：
Nielsen SG;Marschall HR
弧熔岩形成于混杂岩的熔融;沉积物熔融和板状流体不是主要贡献者。在俯冲带，沉积物和热液蚀变的洋壳共同构成俯冲板片的一部分，它们对地表喷发的熔岩的化学成分起作用，形成火山弧。这种物质从板块到上覆地幔楔的运输被认为涉及从板块各个部分释放的离散熔体和流体。我们使用的地球化学数据的荟萃分析，从8个全球代表性的弧表明，熔体和流体从个别板组件不能负责弧熔岩的形成。相反，数据是兼容的模型，首先调用物理混合板组件和地幔楔，广泛称为高压混杂，弧岩浆产生之前。
Arc lavas form from melting of mélange rocks; sediment melts and slab-derived fluids are not major contributors. In subduction zones, sediments and hydrothermally altered oceanic crust, which together form part of the subducting slab, contribute to the chemical composition of lavas erupted at the surface to form volcanic arcs. Transport of this material from the slab to the overlying mantle wedge is thought to involve discreet melts and fluids that are released from various portions of the slab. We use a meta-analysis of geochemical data from eight globally representative arcs to show that melts and fluids from individual slab components cannot be responsible for the formation of arc lavas. Instead, the data are compatible with models that first invoke physical mixing of slab components and the mantle wedge, widely referred to as high-pressure mélange, before arc magmas are generated.