Article (Scientific journals)
δ13C, CO2/3He and 3He/4He ratios reveal the presence of mantle gas in the C02-rich groundwaters of the Ardennes massif (Spa, Belgium)
Defourny, Agathe; Blard, Pierre-Henri; Zimmermann, Laurent et al.
2022In Hydrology and Earth System Sciences, 26 (10), p. 2637-2648
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Keywords :
CO2; groundwater; Spa; isotope ratios; mantle gas; Ardennes; hydrogeology
Abstract :
[en] Although natural CO2-rich groundwaters of eastern Belgium have been known for centuries, the exact origin of their gas is still unclear. This paper presents the results of a sampling campaign in Belgium (Spa, Stoumont, Malmedy): 30 samples of both carbogaseous and non-carbogaseous groundwaters were analyzed for major elements, CO2 content, and carbon isotopic composition. Among them, 13 samples were also analyzed for 3He/4He and 4He/20Ne ratios. The combination of δ13C (between ca. −9 ‰ VPDB1 and −2 ‰ VPDB), CO2/3He ratio (between 1.9×108 and 2.9×109) and 3He/4He (between 0.92 and 2.70 Ra) shows with a high level of confidence that the CO2 in the carbogaseous groundwater of Spa and Bru has a mantle origin. It can likely be attributed to the degassing of the mantle from the neighboring Eifel volcanic fields, located at a distance of 100 km eastwards. The identity and nature of the deep-rooted fractures that act as CO2 transport pathways to the surface are still to be clarified, but several major thrust faults exist in the Rhenish Massif and could connect the Eifel volcanic fields with the studied area.
Research center :
UEE - Urban and Environmental Engineering - ULiège
Disciplines :
Geological, petroleum & mining engineering
Author, co-author :
Defourny, Agathe ;  Université de Liège - ULiège > Urban and Environmental Engineering
Blard, Pierre-Henri 
Zimmermann, Laurent
Jobé, Patrick
Collignon, Arnaud
Nguyen, Frédéric  ;  Université de Liège - ULiège > Urban and Environmental Engineering
Dassargues, Alain  ;  Université de Liège - ULiège > Urban and Environmental Engineering
Language :
Title :
δ13C, CO2/3He and 3He/4He ratios reveal the presence of mantle gas in the C02-rich groundwaters of the Ardennes massif (Spa, Belgium)
Publication date :
19 May 2022
Journal title :
Hydrology and Earth System Sciences
Publisher :
Copernicus GmbH
Volume :
Issue :
Pages :
Peer reviewed :
Peer Reviewed verified by ORBi
Name of the research project :
ROSEAU project, as part of the Walloon program “Doctorat en Entreprise”, co-funded by the SPW Région Wallonne of Belgium and the company Bru-Chevron S.A. (Spadel S.A.), grant number 7984
Funders :
SPW - Service Public de Wallonie [BE]
EU - European Union [BE]
Funding number :
Grant agreement no. 871149
Funding text :
The collaboration with the CRPG of Nancy was made possible thanks to the Europlanet Transnational Access Program, as this project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 871149. The authors acknowledge these two institutions for their support.
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