A distinct metal fingerprint in arc volcanic emissions
A distinct metal fingerprint in arc volcanic emissions
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DOI：
10.1038/s41561-018-0214-5
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发表时间：
2018-10-01
影响因子：
18.3
通讯作者：
Liu, Emma J.
中科院分区：
文献类型：
--
作者：
Edmonds, Marie;Mather, Tamsin A.;Liu, Emma J.
除了在地质时期调节气候的气体外，火山还向大气中排放大量金属，它们在大气中扮演着催化剂、污染物和营养物质的关键角色。在这里，我们将弧玄武岩火山金属排放的测量结果与热点地区的测量结果进行了比较。除了释放出更高的金属通量(类似于建造矿床)外，这些弧光排放物具有明显的成分指纹，与热点地区的弧光排放物相比，特别富含钨、砷、铊、锑和铅。我们认为，火山金属的释放受岩浆水含量和氧化还原的控制：未经历硫化物饱和的水合弧状岩浆产生富金属的含盐水溶液；晚期硫化物的浅层脱气和再吸收作用为夏威夷和冰岛的火山气体输送。尽管全球弧岩浆的化学成分差异很大，但我们的发现表明，与其他环境相比，弧内的火山喷发具有明显的指纹。全球火山金属排放的转变可能发生在地球过去，因为更多被氧化、富含水的岩浆变得普遍，影响了地表环境。
As well as gases that regulate climate over geological time, volcanoes emit prodigious quantities of metals into the atmosphere, where they have key roles as catalysts, pollutants and nutrients. Here we compare measurements of arc basaltic volcano metal emissions with those from hotspot settings. As well as emitting higher fluxes of metals (similar to those building ore deposits), these arc emissions possess a distinct compositional fingerprint, particularly rich in tungsten, arsenic, thallium, antimony and lead when compared with those from hotspots. We propose that volcanic metal emissions are controlled by magmatic water content and redox: hydrous arc magmas that do not undergo sulfide saturation yield metal-rich, saline aqueous fluid; shallow degassing and resorption of late-stage sulfides feeds volcanic gases in Hawai'i and Iceland. Although global arc magma chemistries vary considerably, our findings suggest that volcanic emissions in arcs have a distinct fingerprint when compared with other settings. A shift in global volcanic metal emissions may have occurred in Earth's past as more oxidized, water-rich magmas became prevalent, influencing the surface environment.