Carbon sources in arc volcanism, with implications for the carbon cycle
Carbon sources in arc volcanism, with implications for the carbon cycle
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DOI：
10.1111/j.1365-3121.1992.tb00825.x
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发表时间：
1992-05
期刊：
影响因子：
2.4
通讯作者：
J. Varekamp;R. Kreulen;R. Poorter;M. J. Bergen
中科院分区：
文献类型：
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作者：
J. Varekamp;R. Kreulen;R. Poorter;M. J. Bergen
来自东巽他弧（印度尼西亚）的新的CO2/3 He数据证实了早期的观测结果，即弧火山气体比莫尔环境具有更高的CO2/3 He比率。平均而言，> 80%的弧火山CO2是再循环的，外生碳。地幔楔中加入少量碳酸盐沉积物可以解释弧气的碳丰度和碳同位素数据，但不能解释He同位素观测结果。在弧火山的CO2/3 He是不是强烈依赖于现代槽沉积物（例如深海粘土与富碳酸盐序列）的组成，方解石脉的热液蚀变俯冲板可能会提供一个贡献，弧的再循环碳通量。全球深俯冲沉积物和板碳的总和超过了估计的弧CO2通量，约3.5太摩尔的碳可能每年返回到地幔的会聚区。现代综合过程的莫尔火山作用，板片蚀变，俯冲火山作用不产生大量的碳通量进入外逸层，和海底扩张的速率变化是不太可能导致大气中的CO2作为一个结果，在火山CO2通量的变化的重大变化。然而，强烈的溢流玄武岩火山活动脉冲可能会在一千年左右的时间内改变大气中的二氧化碳含量，并影响全球气候。
New CO2/3 He data from the East Sunda Arc (Indonesia) confirm earlier observations that arc volcanic gases have higher CO2/3 He ratios than MOR environments.On average, > 80% of arc volcanic CO2 is recycled, exogene carbon. Addition of a few percent of carbonate-bearing sediments to the mantle wedge explains much of the carbon abundance andcarbon isotopic data of arc gases, but can not explain the He isotope observations. The CO2/3He in arc volcanoes is not strongly dependent on the composition of modem trough sediments (e.g. deep sea clays vs carbonate-rich sequences), and calcite veins in the hydrothermally altered subducted slab may provide a contribution to the recycled carbon flux of, arcs. The sum of globally deep-subducted sediment and slab carbon exceeds the estimated arc CO2 flux, and approximately 3.5 teramole of carbon may return annually to the mantle in convergent zones. The modem combined processes of MOR volcanism, slab alteration, and subduction volcanism do not produce a substantial carbon flux into the exosphere, and rate-changes in ocean floor spreading are unlikely to cause major changes in atmospheric CO2 as a result of changes in the volcanic CO2 fluxes. Intense pulses of flood basalt volcanism, however, may alter the CO2 contents of the atmosphere over the course of a millenium or so, and influence global climate.