Modification of fumarolic gases by the ice-covered edifice of Erebus volcano, Antarctica
Modification of fumarolic gases by the ice-covered edifice of Erebus volcano, Antarctica
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DOI：
10.1016/j.jvolgeores.2019.05.017
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发表时间：
2019-09-01
影响因子：
2.9
通讯作者：
Sano, Y.
中科院分区：
文献类型：
--
作者：
Ilanko, T.;Fischer, T. P.;Sano, Y.
在冰洞和南极洲埃里伯斯火山温暖的地热地面测量的气体化学表明，气体排放主要是空气，并增加了不同数量的火山二氧化碳。这表明空气在火山建筑物中的广泛循环，以及岩浆脱气作用在空间或时间上的变化。第一个是CO2溶解在水中，导致岩浆三角洲C-13-CO2值的分馏，估计约为-4%。到更重的值，高达1%。假设所有的岩浆CO2都溶解在中性水中作为HCO 2 '，这需要超过120摄氏度的热液温度。然而，可能存在其他相，如方解石，这意味着甚至更高的温度，而较低的水pH值可能导致类似的同位素比在低得多的温度下，如60摄氏度，pH值为53。大部分的岩浆CO2必须损失到这个热液系统或与空气混合。热液的影响局限于火山的某些地区，这可能与以前的研究中通过地震层析成像确定的高速区有关。相比之下，两个具有较强岩浆特征的地点位于代表可能的浅岩浆储存的低速区之上。第二个变化是从深源和空气来源的气体中去除氧气。这可能是由于地下的主要条件，因为它与气体的原始来源和热液变化无关;因此可能影响具有岩浆、空气或热液特征的地点。(C)2019 Elsevier B. V.版权所有。
The chemistry of gases measured in ice caves and from warm geothermal ground at Erebus volcano, Antarctica, shows that gas emissions are dominated by air, with varying amounts of added volcanic CO2. This suggests widespread circulation of air through the volcanic edifice, as well as spatially or temporally varying contributions from magmatic degassing.The resulting gases are further modified by two processes. The first is CO2 dissolution in water, resulting in fractionation from magmatic delta C-13-CO2 values, which are estimated to be around -4%., to heavier values, up to 1%.. Assuming all magmatic CO2 is dissolved in neutral water as HCOi', this requires hydrothermal temperatures of over 120 degrees C. However, other phases such as calcite may be present, implying even higher temperatures, while lower water pH values could result in similar isotope ratios at much lower temperatures, such as 60 degrees C at pH of 53. A large proportion of magmatic CO2 must be lost to this hydrothermal system or to mixing with air. The hydrothermal influence is localized to certain areas on the volcano, which may be associated with high velocity zones identified in previous studies by seismic tomography. Two sites with stronger magmatic signatures, by contrast, are above low velocity zones representing possible shallow magma storage.The second modification is the removal of oxygen from both deeply-sourced and air-derived gases. This is likely due to prevailing conditions in the subsurface, as it is independent of the original source of the gases and of hydrothermal modifications; and thus may affect sites with magmatic, air-like, or hydrothermal signatures. (C) 2019 Elsevier B.V. All rights reserved.