Serpentinization-sourced hydrogen systems in rift inversion orogens: a geological/holistic perspective

Serpentinization-sourced H₂ has become a promising source of decarbonated energy. It can be generated in fiver tectonic settings, namely: (1) intra-craton settings, (2) divergent settings such as hyperextended rifts, ocean continent transitions and mid ocean ridges, (3) subduction systems, (4) obduction, and (5) rift-inverted orogens. Most recently, many studies have been focusing on parts of the H₂-system, i.e., the kitchen, plumbing system, reservoir, cap rock and trapping and preservation mechanisms or on the detection of leaking natural H₂ systems at or near the surface. However, a holistic understanding of a serpentinization-sourced H₂ system is still in its infancy and an exploration protocol tailored to the different tectonic settings is missing to date.   

In our study, we aim to develop a protocol to predict, quantify and explore serpentinization-sourced H₂ systems in rift-inverted orogens. To do so, we use the Grisons area (SE Alps in Switzerland) as a field analogue. In this area all play-elements of the serpentinization-sourced H₂ system exist and can be accessed and the rift and convergent structures are well exposed and investigated. This allows us to examine the interplay, in time and space, between the play-elements of a serpentinization-sourced H₂ system and to develop a predictive exploration protocol. In this perspective, we first seek  to define a serpentinization-sourced H₂ system in a rift-inversion orogen and second to address when and where the serpentinization-sourced H₂ forms, what are the essential play-elements and how they interact in time and space, impacting the location and timing of H₂ production by considering the two dominant parameters, temperature and access to water, which determine entry into the serpentinization window (kitchen) for mantle rocks. In our presentation, we show the first preliminary results of our holistic, geological approach aiming to integrate different data sets from the Grisons area. We are aware that to develop a predictive play-element based exploration protocol for a serpentinization-sourced H₂ system in rift-inverted orogens, similar to that developed in oil and gas systems, further studies will be necessary.