Natural Hydrogen in the northern Semail Ophiolite: A case study in the Emirate of Ras Al Khaimah, UAE
Gabriel Pasquet, Keanu Loiseau, Mohamed Diatta, Giacomo Firpo, P. H. Swire, Andrew Amey, T. Burckhart, Isabelle Moretti
Abstract
The Semail Ophiolite provides a rare geological snapshot of oceanic lithosphere rocks at the surface. Extensive studies in the southern region, particularly within the Sultanate of Oman, have highlighted active serpentinization processes and the associated natural hydrogen (H 2 ) production. However, the northern region of the ophiolite remains underexplored. This study aims to fill this knowledge gap by investigating the potential natural H 2 resources in the Emirate of Ras Al Khaimah (RAK), in the United Arab Emirates (UAE). Comprehensive surface gas measurements allowed us to construct an H 2 distribution map which reveals H 2 presence and, as usual, show that the faults are preferential migration pathways. We also examine the correlation between gas emissions and lithological variations from the metamorphic sole to various mantle peridotites and crustal upper gabbros. Findings indicate that structural windows exposing the metamorphic sole are key areas for locating higher H 2 concentration measurements. Additionally, prominent structural lineaments between the layered and upper gabbros formations represent potential migration pathways for H 2 from the underlying peridotites. New alkaline blue pools (pH∼9 and ongoing carbonation) have been identified; the gases sampled in these bubbling pools are very diversified. As in Oman, H 2 -rich gas, up to 88% after air correction, have been found but also N 2 and CH 4 -rich ones. A seasonal variation in the H 2 /N 2 ratio was observed at one site, suggesting significant fluctuations within the underground water table, which is necessary for H 2 generation. These new measurements highlight the northern Semail Ophiolite's potential for natural H 2 exploration and production (E&P) in the RAK Emirate. • Soil gas measurement campaigns for H 2 migration pathways on the Semail Ophiolite, UAE. • Up to 87% of H 2 in bubbling spring. • Seasonal variation on the H 2 /N 2 ratio of a bubbling spring.