A new continental hydrogen play in Damara Belt (Namibia)

Serpentinization is commonly presented as the main source of natural hydrogen (H₂) in the continental domains. However, recent works in Australia and Brazil showed that Archean-Paleoproterozoic banded iron formations could be another natural source of H₂ gas. Although the reaction that produces hydrogen is similar (Fe²⁺ oxidation-H₂O reduction process), the iron content may be higher in banded iron formations than in mafic igneous lithologies, potentially generating H₂ more efficiently. Here, we present structural evidence that reported H₂ emissions from Waterberg Basin, Namibia are associated with underlying Neoproterozoic banded iron formations-the Chuos Formation. Magnetite, a known H₂-generating mineral, is ubiquitous and accompanied by other suspected H₂-generating minerals (biotite and siderite) in Chuos Formation. Magnetite occurs either as pervasive cm to dm continuous metamorphic laminations in foliation and fractures planes and/or diffusely disseminated in metachert and metacarbonate levels. From this, we infer that metamorphism does not negatively affect the Fe²⁺ content that is required to generate hydrogen. H₂ seepages in Waterberg Basin suggest that an active H₂-generating system may exist at depth and that the presence of potential traps and reservoirs is likely based on field observations.