10.5880/GFZ.2.5.2024.001 Zwaan, Frank Frank Zwaan 0000-0001-8226-2132 GFZ German Research Centre for Geosciences, Potsdam, Germany University of Fribourg, Department of Geosciences, Fribourg, Switzerland Pilz, Peter Peter Pilz GFZ German Research Centre for Geosciences, Potsdam, Germany Niedermann, Samuel Samuel Niedermann 0000-0003-1626-5284 GFZ German Research Centre for Geosciences, Potsdam, Germany Zimmer, Martin Martin Zimmer 0000-0002-8848-2336 GFZ German Research Centre for Geosciences, Potsdam, Germany Lefeuvre, Nicolas Nicolas Lefeuvre 0000-0001-5527-8016 CVA Group, Pau, France Petit, Valentin Valentin Petit CVA Group, Pau, France University of Pau et des Pays de l’Adour, Pau, France Vieth-Hillebrand, Andrea Andrea Vieth-Hillebrand 0000-0002-3688-662X GFZ German Research Centre for Geosciences, Potsdam, Germany Gaucher, Eric C. Eric C. Gaucher 0000-0002-7976-8455 Lavoisier H2 Geoconsult, Chamonix, France Schmidt-Hattenberger, Cornelia Cornelia Schmidt-Hattenberger 0000-0002-3058-7469 GFZ German Research Centre for Geosciences, Potsdam, Germany Brune, Sascha Sascha Brune 0000-0003-4985-1810 GFZ German Research Centre for Geosciences, Potsdam, Germany University of Potsdam, Potsdam, Germany GFZ Data Services 2024 Zwaan, Frank Frank Zwaan 0000-0001-8226-2132 GFZ German Research Centre for Geosciences, Potsdam, Germany University of Fribourg, Department of Geosciences, Fribourg, Switzerland Zwaan, Frank Frank Zwaan 0000-0001-8226-2132 GFZ German Research Centre for Geosciences, Potsdam, Germany University of Fribourg, Department of Geosciences, Fribourg, Switzerland Zwaan, Frank Frank Zwaan 0000-0001-8226-2132 GFZ German Research Centre for Geosciences, Potsdam, Germany University of Fribourg, Department of Geosciences, Fribourg, Switzerland Zwaan, Frank Frank Zwaan 0000-0001-8226-2132 GFZ German Research Centre for Geosciences, Potsdam, Germany University of Fribourg, Department of Geosciences, Fribourg, Switzerland Zwaan, Frank Frank Zwaan 0000-0001-8226-2132 GFZ German Research Centre for Geosciences, Potsdam, Germany University of Fribourg, Department of Geosciences, Fribourg, Switzerland Pilz, Peter Peter Pilz GFZ German Research Centre for Geosciences, Potsdam, Germany Niedermann, Samuel Samuel Niedermann 0000-0003-1626-5284 GFZ German Research Centre for Geosciences, Potsdam, Germany Zimmer, Martin Martin Zimmer 0000-0002-8848-2336 GFZ German Research Centre for Geosciences, Potsdam, Germany Lefeuvre, Nicolas Nicolas Lefeuvre 0000-0001-5527-8016 CVA Group, Pau, France Petit, Valentin Valentin Petit CVA Group, Pau, France University of Pau et des Pays de l’Adour, Pau, France Vieth-Hillebrand, Andrea Andrea Vieth-Hillebrand 0000-0002-3688-662X GFZ German Research Centre for Geosciences, Potsdam, Germany Gaucher, Eric C. Eric C. Gaucher 0000-0002-7976-8455 Lavoisier H2 Geoconsult, Chamonix, France Schmidt-Hattenberger, Cornelia Cornelia Schmidt-Hattenberger 0000-0002-3058-7469 GFZ German Research Centre for Geosciences, Potsdam, Germany Brune, Sascha Sascha Brune 0000-0003-4985-1810 GFZ German Research Centre for Geosciences, Potsdam, Germany University of Potsdam, Potsdam, Germany Geochemistry Laboratories (GFZ German Research Centre for Geosciences, Germany) GFZ German Research Centre for Geosciences, Potsdam, Germany Laboratory for Compound-specific Isotope Analysis (GFZ German Research Centre for Geosciences, Germany) GFZ German Research Centre for Geosciences, Potsdam, Germany Noble Gas Lab (GFZ German Research Centre for Geosciences, Germany) GFZ German Research Centre for Geosciences, Potsdam, Germany Zwaan, Frank GFZ German Research Centre for Geosciences, Potsdam, Germany Dataset 10.1029/2021GC009917 10.1016/j.apgeochem.2022.105396 10.1016/S0016-7037(97)00102-6 CC BY 4.0 This data set contains the results from a 2023 GFZ Innovative Research Expedition project to explore for natural hydrogen gas (H2) occurrences in the NW Pyrenean foreland, near the town of Biarritz in France. The data represent in-situ measurements of soil and spring water gas, as well as in-situ spring water property measurements, complemented with laboratory analysis results of gas contents and noble gas isotopic compositions of gas and spring water samples collected during the expedition.

This GFZ Innovative Research Expedition was inspired by previous exploration efforts in the region by Lefeuvre et al. (2021, 2022). These authors detected elevated concentrations of natural H2 gas in the soil and interpreted this natural H2 to be derived from serpentinizing mantle rocks below the Pyrenees.

The main aims of this expedition were the following: (1) in-situ measuring soil gas contents and taking soil gas samples for laboratory analysis at a site near the town of Peyrehorade in the NW of the general study area of Lefeuvre et al. (2021), thus improving the soil gas data coverage along the NW end of the North Pyrenean Frontal Thrust (NPFT); (2) taking gas samples from degassing springs (or water samples from non-degassing springs to be degassed in the lab) in the general Lefeuvre et al. (2021) study area for additional laboratory analysis of gas contents and noble gas isotopic compositions, which may be indicative of (deep) gas origins; and (3) performing a detailed soil gas analysis by means of a portable mass spectrometer at Sauveterre-de-Béarn, a site along the NPFT where Lefeuvre et al. (2022) measured elevated concentrations of natural H2 in the soil. Furthermore, we also measured the properties of the visited springs (temperature, pH, conductivity) while on site, and performed additional in-situ soil gas measurements from manual drillholes.

Details on the measurement and sampling methods, on the laboratory analyses, as well as the results of these measurements and analyses are provided in the data description file

The expedition involved six field days in July 2023, during which a total of 26 sites were visited. These sites were selected for their vicinity near a major geological contact or fault zone that could have facilitated upward circulation of gas or (thermal) water from the (deep) subsurface (i.e., potentially from the mantle).
Study site in the Pyrenees -1.6 -0.4 43 43.9 Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ http://dx.doi.org/10.13039/501100010956 GFZ Innovative Research Expedition 2023 Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ http://dx.doi.org/10.13039/501100010956 GFZ Discovery Fund fellowship CVA Group, Pau, France University of Pau et des Pays de l’Adour, Pau, France