Vincent Roche

I graduated with a Ph.D. in 2018 from the University of Orléans and BRGM (the French geological survey). My Ph.D. focused on the Menderes geothermal Province (Western Anatolia, Turkey) that offers the opportunity to study amagmatic high-temperature geothermal systems, without necessarily invoking a magmatic heat source in the upper crust. Then, I have been employed as a Postdoctoral Researcher at the “Institut des Sciences de la Terre de Paris” (Sorbonne University), and I have worked in partnership with TotalEnergies on rifted and transform margins at the east African scale. Then I have a post-doc position at Pau University where I worked on natural hydrogen in partnership with 45-8 Energy. My project was to explain the correlations between natural H2 generation and the presence of iron rich rocks. Currently, I hold a position of Associate Professor at the University of Le Mans.

My research focuses on the evolution of geodynamics and tectonics and their consequences for natural resources. I use a field approach (e.g., structural geology, petrography) combined with laboratory analysis (e.g., geochronology) and numerical modelling. I have mainly worked in Greece, Turkey, Namibia and Uruguay.

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. The subcircular depressions are numerous in this basin (> 2200) and cover an area of 4,000 square kilometers. The highest density occurs in the central basin a few kilometers away from Waterberg Plateau. Overall, however, the subcircular depressions distribution appears to be random. Magnetite, a known H2‑generating mineral, is ubiquitous and accompanied by other suspected H2‑generating minerals (biotite and siderite) in Chuos Formation. Wherever, Chuos Formation is deformed and metamorphosed as evidenced by the presence of biotite. 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. Based on the magnetic response map of the different lithologies around Waterberg Basin, the spatial distribution of Chuos Formation is inferred to underlie much if not most of Waterberg Basin. At some places, Chuos Formation continuously outcrops over several kilometers (>150 km) with an estimated thickness of several hundreds of meters, which is consistent with our field observations. We assume that H2 measurements in Waterberg Basin may be associated to an active H2‑generating system by oxidation of banded iron formations in subsurface. In addition, magmatic dolerite sills are also present in the basin, and may in parallel act as seals to allow accumulation of H2 like in Mali. The banded iron formations that constitute more than 60% of global iron ore reserves, should be targeted for H2 exploration.

Vincent Roche

University of Le Mans

Associate professor

< Back