Geochemical datasets associated with the article “Tracking Deep Magma Migration Through Diffuse CO₂ Degassing: Insights from Piton de la Fournaise Volcano (2013–2023)”

Here, we present the datasets associated with the article “Tracking Deep Magma Migration Through Diffuse CO₂ Degassing: Insights from Piton de la Fournaise Volcano (2013–2023)” submitted to the AGU journal “Geochemistry, Geophysics, Geosystems”. The data are (1) the soil CO2 concentrations, air temperatures, atmospheric pressures and δ13C isotopic compositions recorded by the four soil CO2 monitoring stations of the Observatoire Volcanologique du Piton de la Fournaise – Institut de physique du Globe de Paris (OVPF/IPGP) from the date of their respective installation up to May 22rd 2023, as well as (2) the geochemical composition of lava and tephra samples from eruptions which occurred between 2013 and 2023. Soil CO2 concentrations, air temperatures and atmospheric pressures are acquired hourly and transmitted in real time at the Observatoire Volcanologique du Piton de la Fournaise (OVPF/IPGP). Stations PNRN, PCRN, BLEN and GITN are located on the island of La Réunion. The stations were designed by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) Sezione di Palermo (Gurrieri et al., 2008). For the measurement of soil CO2 concentrations, a 50 cm long probe is inserted into the soil and connected by a Teflon pipe to a Gascard NG dual-wavelength nondispersive infrared gas analyzer (CO2 gas measurement range 0–10%). The molar fraction of CO2 is measured in a soil-air gas mixture pumped at 0.8 L/min and are automatically corrected for air temperature and atmospheric pressure effects on gas molecular density (Gurrieri and Valenza, 1988). Air temperature and atmospheric pressure are measure at each station a height of two meters. Temperature is measured by Mela® sensors PK-ME with a precision of ± 0.2K. Pressure is measured by STS® sensors ATM.ECO with a precision of ± 0.375 psi. The CO₂ isotopic composition (δ13C) is regularly (approximately quarterly) monitored at all four soil CO2 stations. Soil gas samples are collected in Labco 12 ml Exetainer vials. Ground air is manually pumped from each station probe after sealing with a syringe, then collected in vials after purging. CO₂ concentrations and δ13C ratios are analyzed via gas chromatography and isotope ratio mass spectrometry (GC-IRMS) at INGV in Palermo. Lava and tephra samples were collected and in most cases quenched in water during or shortly after each eruptive event. The date of each sample corresponds to the date the magma was erupted. Trace elements were measured by ICP-MS at the Laboratoire Magmas et Volcans (OPGC; Clermont Ferrand). Samples were dried, crushed and powdered before analysis. The strontium was purified using Eichrom specific resins (Sr.Spec), and its isotopic composition was measured by Thermal Ionisation Mass Spectrometry (TIMS) at LMV with a precision of 15 ppm/amu (2σ). A detailed description of the analytical methods is given in Vlastélic et al. (2009). (2025-07-23)