Carbon-bearing gas geothermometers for volcanic-hydrothermal systems
Carbon-bearing gas geothermometers for volcanic-hydrothermal systems
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DOI：
10.1016/j.chemgeo.2013.05.006
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发表时间：
2013-08
期刊：
影响因子：
3.9
通讯作者：
J. Fiebig;F. Tassi;W. D’Alessandro;O. Vaselli;A. Woodland
中科院分区：
文献类型：
--
作者：
J. Fiebig;F. Tassi;W. D’Alessandro;O. Vaselli;A. Woodland
研究了希腊Nisyros、维苏维奥、La Solfatara （Campi Flegrei）和意大利Pantelleria火山-热液气体中含碳物种（CO、CO2、CH4、C2H6、C3H8、c2h4和C3H6）的遗传关系。ch4 - co2体系的表观碳同位素温度为Nisyros ~ 360°C， Vesuvio ~ 420 ~ 460°C, La Solfatara ~ 450°C, Pantelleria ~ 540°C。这些温度由测量的丙烯/丙烷和H2/H2O浓度比证实。ch4和co2在沸腾前在单一液相中达到平衡，而丙烯和丙烷在饱和水蒸汽相中达到平衡。在这些高焓热液系统中，沸腾可能是等温发生的。一旦蒸汽从母体液体中提取出来，CO/ co2对上升气体遇到的温度梯度反应最为敏感。结果表明，ch4 - co2同位素地温计可以提供与火山活动有关的深部热液温度的可靠信息。丙烯/丙烷和H2/H2O的浓度比应与co2和ch4的碳同位素组成一起测量，以对表观碳同位素温度的地质意义提供独立的约束。
The genetic relationship between carbon-bearing species (CO, CO2, CH4, C2H6, C3H8, C2H4and C3H6) was investigated in volcanic-hydrothermal gases emitted from Nisyros (Greece), Vesuvio, La Solfatara (Campi Flegrei) and Pantelleria (all Italy).Apparent carbon isotopic temperatures of the CH4–CO2system are ~ 360 °C at Nisyros, 420–460 °C at Vesuvio, ~ 450 °C at La Solfatara and ~ 540 °C at Pantelleria. These temperatures are confirmed by measured propene/propane and H2/H2O concentration ratios. CH4and CO2equilibrate in the single liquid phase prior to the onset of boiling, whereas propene and propane attain equilibrium in the saturated water vapor phase. Boiling in these high-enthalpy hydrothermal systems might occur isothermally. Once vapor has been extracted from the parental liquid, CO/CO2responds most sensitively to the temperature gradient encountered by the ascending gases.Our results imply that the CH4–CO2isotopic geothermometer can provide reliable information about temperatures of deep hydrothermal liquids associated with volcanism. Propene/propane and H2/H2O concentration ratios should be measured along with the carbon isotopic composition of CO2and CH4to provide independent constraints on the geological significance of the apparent carbon isotopic temperatures.