Roche V, Geymond U, Boka-Mene M, Delcourt N, Portier E, Revillon S, Moretti I
Laboratoire des Fluides Complexes et leurs Réservoirs - IPRA, E2S-UPPA, TotalEnergies, CNRS, Université de Pau et des Pays de l'Adour, UMR5150, Pau, France.
Laboratoire de Planétologie et Géosciences, LPG UMR 6112, CNRS, Le Mans Université, Univ Angers, Nantes Université, Avenue Olivier Messiaen, 72085, Le Mans, France.
Sci Rep. 2024 May 22;14(1):11655. doi: 10.1038/s41598-024-62538-6.
Serpentinization is commonly presented as the main source of natural hydrogen (H) 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 gas. Although the reaction that produces hydrogen is similar (Fe oxidation-HO reduction process), the iron content may be higher in banded iron formations than in mafic igneous lithologies, potentially generating H more efficiently. Here, we present structural evidence that reported H emissions from Waterberg Basin, Namibia are associated with underlying Neoproterozoic banded iron formations-the Chuos Formation. Magnetite, a known H-generating mineral, is ubiquitous and accompanied by other suspected H-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 content that is required to generate hydrogen. H seepages in Waterberg Basin suggest that an active H-generating system may exist at depth and that the presence of potential traps and reservoirs is likely based on field observations.
蛇纹石化通常被认为是大陆地区天然氢（H）的主要来源。然而，澳大利亚和巴西最近的研究表明，太古宙—古元古代条带状含铁建造可能是氢气的另一个天然来源。尽管产生氢气的反应相似（铁氧化—水还原过程），但条带状含铁建造中的铁含量可能高于镁铁质火成岩岩性，有可能更高效地产生氢气。在此，我们提供结构证据表明，纳米比亚沃特贝格盆地报告的氢排放与下伏新元古代条带状含铁建造——乔斯建造有关。磁铁矿是一种已知的产氢矿物，在乔斯建造中普遍存在，并伴有其他疑似产氢矿物（黑云母和菱铁矿）。磁铁矿以两种形式出现，一种是在片理和断裂面中呈普遍的厘米到分米级连续变质纹层，另一种是在变质燧石和变质碳酸盐层中呈弥散状分布。据此，我们推断变质作用不会对产氢所需的铁含量产生负面影响。沃特贝格盆地的氢渗漏表明，深部可能存在一个活跃的产氢系统，并且根据野外观察，可能存在潜在的圈闭和储层。
