Isotope compositions in a natural gas seep, French Alps

The Fontaine Ardente (FA) and Rochasson (ROC) natural gas seepage sites are located southwest (FA) and east (ROC) of Grenoble, France. For both field sites, gas is thought to originate from buried Middle Jurassic mudstones and argillaceous limestones and thought to migrate upward along small faults. At FA, the site located along a small seepage close to the river bed of a small creek. The gas seepage site at ROC is located along the flank of a thalweg and is linked to a small landslide in clayey horizons.

New methane clumped isotope data is correlated to previously published data by Gal et al (2017) and recent isotopic data acquired within SECURe deliverable 3.4.

During October 2019, 5 samples were collected from the FA and ROC sites and the following analyses were conducted:

• Gas composition (C1-C5, CO2, N2, H2S, Ar) and and stable isotope analyses (methane δ13C and δD, CO2 δ13C, δ15N)
• Methane clumped isotope analyses (Δ13CD and ΔDD)

The dataset was created within SECURe project (Subsurface Evaluation of CCS and Unconventional Risks) - https://www.securegeoenergy.eu/. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 764531