Volcanoes find a new carbon platform The geological carbon cycle assumes that carbon is emitted by volcanic eruptions and removed through various forms of burial. Mason et al. found that not all volcanic eruptions have the same source for carbon in their volcanic gas. Arc volcanic activity appears to harvest carbon from old carbonate platforms, which results in a massive difference in the isotopic signature of the carbon emitted during eruption. This discovery requires revision of the global carbon cycle, decreasing the amount of organic carbon believed to be being buried. Science, this issue p. 290 A revision in the carbon isotope budget from the global volcanic arc gas output requires less organic carbon burial. The flux of carbon into and out of Earth’s surface environment has implications for Earth’s climate and habitability. We compiled a global data set for carbon and helium isotopes from volcanic arcs and demonstrated that the carbon isotope composition of mean global volcanic gas is considerably heavier, at –3.8 to –4.6 per mil (‰), than the canonical mid-ocean ridge basalt value of –6.0‰. The largest volcanic emitters outgas carbon with higher δ13C and are located in mature continental arcs that have accreted carbonate platforms, indicating that reworking of crustal limestone is an important source of volcanic carbon. The fractional burial of organic carbon is lower than traditionally determined from a global carbon isotope mass balance and may have varied over geological time, modulated by supercontinent formation and breakup.

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地壳碳的再动员可能主导火山弧排放

火山找到新的碳平台 地质碳循环假设碳是由火山喷发排放的，并通过各种形式的掩埋被清除。梅森等人。发现并非所有火山喷发的火山气体中的碳来源都相同。弧形火山活动似乎从旧的碳酸盐平台收集碳，这导致喷发期间排放的碳的同位素特征存在巨大差异。这一发现需要修正全球碳循环，减少被认为被掩埋的有机碳的数量。科学，这个问题 p。290 对全球火山弧气体输出的碳同位素预算的修订需要较少的有机碳埋藏。进出地球表面环境的碳通量对地球的气候和宜居性有影响。我们汇编了火山弧中碳和氦同位素的全球数据集，并证明全球平均火山气体的碳同位素组成比典型的大洋中脊玄武岩重得多，为 –3.8 至 –4.6 per mil (‰) –6.0‰的值。最大的火山排放源以较高的 δ13C 释放碳，并且位于具有增生碳酸盐台地的成熟大陆弧，表明地壳灰岩的再加工是火山碳的重要来源。有机碳的部分掩埋低于传统上根据全球碳同位素质量平衡确定的，并且可能随地质时间而变化，受超大陆形成和分裂的影响。