A new continental hydrogen play in Damara Belt (Namibia)
Vincent Roche, Ugo Geymond, Molly Boka-Mene, N. Delcourt, Éric Portier, Sidonie Révillon, Isabelle Moretti
Abstract
Abstract Serpentinization is commonly presented as the main source of natural hydrogen (H 2 ) in the continental domains. However, recent works in Australia and Brazil showed that Archean–Paleoproterozoic banded iron formations could be another natural source of H 2 gas. Although the reaction that produces hydrogen is similar (Fe 2+ oxidation—H 2 O reduction process), the iron content may be higher in banded iron formations than in mafic igneous lithologies, potentially generating H 2 more efficiently. Here, we present structural evidence that reported H 2 emissions from Waterberg Basin, Namibia are associated with underlying Neoproterozoic banded iron formations—the Chuos Formation. Magnetite, a known H 2 -generating mineral, is ubiquitous and accompanied by other suspected H 2 -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 Fe 2+ content that is required to generate hydrogen. H 2 seepages in Waterberg Basin suggest that an active H 2 -generating system may exist at depth and that the presence of potential traps and reservoirs is likely based on field observations.