Multi‐kilometre long pathway of geofluids migration: Clues concerning an ophiolite serpentinization setting possibly responsible for the inferred abiotic provenance of methane in thermal water outflows of the South‐West Carpathians (Romania)

Abstract

Methane occurrences displaying signatures of a possible abiotic origin had previously been reported in the South‐West Carpathians (Romania). Such an accumulation, at Tisoviţa, was intercepted by a well drilled in an ophiolitic rocks massif, whereas in two other localities—situated tens of kilometres faraway—the concerned methane is released via thermal groundwater outflows that are apparently not associated with any ultramafic products. By using groundwater ionic compositions, corroborated with previously published isotopic (13C‐CH4, 2H‐CH4, 3He/4He) and molecular gas analyses, we assessed in more detail the conjectured abiotic provenance of methane, and quantitatively investigated the hypothesis of a progressive mixing between two, abiotic and thermogenic, methane end‐members. The corresponding geofluids behaviour was modelled by hypothesizing a “concealed” ophiolite serpentinization setting (largely similar to that at Tisoviţa), whose abiotic methane production was “diverted” towards remote discharges at ground surface, via a ~20‐km‐long flowpath supposedly generated by recently operating extensional tectonics.

Characterizing Natural Hydrogen Occurrences in the Paris Basin Using OCR-Enhanced Well Database Studies

“…Notable examples include the "Bougou-1" well, which was drilled in 1987 in Mali, the concentration of H 2 was found to be 98 vol% (Maiga et al, 2023). The "Tisovita well", which was drilled before 1978 in Romania, the concentration of H 2 was found to be 28.7 vol% (Mitrofan et al, 2021). The "#1 Wilson Well" drilled in 2006 in the Kensas (USA).…”

Characterizing Natural Hydrogen Occurrences in the Paris Basin From Historical Drilling Records

“…The “Bougou‐1” water exploration well, which was drilled in 1987 in Mali, revealed H 2 concentration of 98 vol% at the well head (Maiga et al., 2023). The “Tisovita geothermal well,” which was drilled in the 1970’ in Romania, shown H 2 concentration as high as 28.7 vol% (Mitrofan et al., 2021). The “#1 Wilson” hydrocarbon exploration well, drilled in 2006 in the Kansas (USA), displayed H 2 concentration of 10.0 vol% (Newell et al., 2007).…”