Programme des sessions > Recherche par auteur > Dimasi Francesca

Climate-CO2 emission models point to the urgency for European society to transition from high to

low carbon energy sources. In this frame, H2 could be a key component of the decarbonization

strategy. Among the various colours of H2, white (i.e., native) H2 is one of the most promising. The

most efficient way to produce native H2 is serpentinization, a high temperature hydrothermal

process that forms serpentinites from Earth mantle rocks. This hydrothermal alteration

transforms primary magmatic Fe-Mg-bearing silicates (olivine, pyroxenes) into secondary hydrous

minerals (e.g. serpentine, brucite) and oxides (magnetite). Serpentinization also produces

molecular hydrogen (H2) through oxidation of ferrous Fe (FeII) released from the dissolving

primary minerals, to ferric Fe (FeIII) that precipitates in serpentine and magnetite. The

serpentinization process has been extensively documented at various geological settings such as

mid-ocean ridges or subduction zones. In contrast, it has received much less attention at rift

inverted orogens and continental rifts, representing classical sources of oil and gas, but nowadays

being at the forefront of carbon capture, geothermal energy, and new decarbonated energy

resources such as native hydrogen. In conclusion, understanding the iron redox state in a Wilson

cycle will allow us to predict when, where and how serpentinized sourced hydrogen is produced,

which is a prerequisite to develop a successful exploration strategy.

Our approach to achieve this goal is based on a representative sampling area, state-of-the-art

analyses and modelling (the evolution of redox and the production of H2). A series of analytical

methods will be conducted on serpentinites from well-defined sites (Tasna, Platta, Totalp, Val

Malenco and Lanzo) documenting the Wilson cycle of the Alpine-Tethys system. The analysis will

constrain the conditions of serpentinization, i.e., temperature of fluid-rock interactions, PT paths

recorded by mantle rocks, and redox state. Finally, the new data will constrain the evolution of

iron speciation and H2 production during serpentinization and may be used to either test or

calibrate numerical modelling results used for the quantification of H2 production.