Geochemistry of volcanic and hydrothermal gases of Mutnovsky volcano, Kamchatka: evidence for mantle, slab and atmosphere contributions to fluids of a typical arc volcano
Geochemistry of volcanic and hydrothermal gases of Mutnovsky volcano, Kamchatka: evidence for mantle, slab and atmosphere contributions to fluids of a typical arc volcano
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堪察加穆特诺夫斯基火山的火山和热液气体的地球化学：地幔、板片和大气对典型弧火山流体贡献的证据
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Y. Taran
中科院分区：
文献类型：
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作者：
M. Zelenski;Y. Taran
我们报告了堪察加半岛穆特诺夫斯基火山的火山和地热流体的化学成分（主要和痕量成分，包括轻质烃）、氢、氧、氦和氮同位素比率。讨论了流体地球化学的几个方面：化学平衡、不同来源流体的混合、母岩浆气体成分的评估以及堪察加俯冲带不同储层流体对岩浆蒸气的贡献。在活性物质中，火山蒸气中的氢和一氧化碳在 >300°C 的温度下与 SO2-H2S 氧化还原对达到化学平衡。在接近排放温度时达到饱和和不饱和轻质烃之间的亚稳态平衡。甲烷不平衡。穆特诺夫斯基陨石坑的三个喷气孔场可以区分出三种不同的流体来源：（1）来自大型对流岩浆体的岩浆气体通过活动漏斗排出，这是一个年轻的陨石坑，具有最热的喷气孔（高达 620°C），占火山气体总产量的约 80%； (2) 来自主火山口底部区域（96-280°C 喷气孔）下方单独浅岩浆体的火山流体； (3) 来自主火山口上部区域（96–285°C 喷气孔）的相对和绝对浓度较高的 CH4 热液。使用水同位素以及 He 与活动漏斗气体中其他成分之间的相关性来估计母岩浆气体的成分。 Mutnovsky 火山和热液流体的 He-Ar-N2 系统学与氮库存中大量源自板片的沉积氮输入一致，我们计算出只有约 1% 的岩浆 N2 源自地幔，<<1% 来自弧地壳。
We report chemical compositions (major and trace components including light hydrocarbons), hydrogen, oxygen, helium and nitrogen isotope ratios of volcanic and geothermal fluids of Mutnovsky volcano, Kamchatka. Several aspects of the geochemistry of fluids are discussed: chemical equilibria, mixing of fluids from different sources, evaluation of the parent magmatic gas composition and contributions to magmatic vapors of fluids from different reservoirs of the Kamchatkan subduction zone. Among reactive species, hydrogen and carbon monoxide in volcanic vapors are chemically equilibrated at temperatures >300°C with the SO2-H2S redox-pair. A metastable equilibrium between saturated and unsaturated light hydrocarbons is attained at close to discharge temperatures. Methane is disequilibrated. Three different sources of fluids from three fumarolic fields in the Mutnovsky craters can be distinguished: (1) magmatic gas from a large convecting magma body discharging through Active Funnel, a young crater with the hottest fumaroles (up to 620°C) contributing ~80% to the total volcanic gas output; (2) volcanic fluid from a separate shallow magma body beneath the Bottom Field of the main crater (96–280°C fumaroles); and (3) hydrothermal fluid with a high relative and absolute concentrations of CH4 from the Upper Field in the main crater (96–285°C fumaroles). The composition of the parent magmatic gas is estimated using water isotopes and correlations between He and other components in the Active Funnel gases. The He-Ar-N2 systematics of volcanic and hydrothermal fluids of Mutnovsky are consistent with a large slab-derived sedimentary nitrogen input for the nitrogen inventory, and we calculate that only ~1% of the magmatic N2 has a mantle origin and <<1% is derived from the arc crust.