Imaging and quantifying ophiolite-hosted natural hydrogen potential in the northern UAE Semail Ophiolite using petrophysically guided joint inversion of geophysical data

Natural hydrogen (H₂) emissions in the northern United Arab Emirates (UAE) occur within the northern continuation of the Semail Ophiolite, where serpentinized peridotites, fault permeability, and groundwater circulation jointly control H₂ generation and migration. Recent soil-gas surveys in Ras Al Khaimah (RAK) and the Masafi structural window report systematic H₂ anomalies above a regional background, including locally elevated concentrations along fault corridors and lithological contacts. In parallel, regional geophysical studies in the UAE–Oman mountain belt provide independent constraints on the ophiolite’s three-dimensional architecture, indicating kilometre-scale thickness variations and structural segmentation, while broadband magnetotelluric (MT) models resolve resistivity contrasts and conductive zones consistent with fluid-focused deformation along major fault systems.

Here we develop an integrated, exploration-oriented workflow that constrains depth-resolved ultramafic/serpentinized source geometry and evaluates its spatial consistency with mapped surface H₂ anomalies. We combine available gravity and magnetic datasets with petrophysical constraints and geological priors to perform petrophysically guided joint inversion, targeting (i) the depth extent and volume of ultramafic bodies, (ii) the distribution of serpentinization-related physical property changes, and (iii) structurally controlled corridors that may promote water ingress and gas migration. Where available, MT-derived constraints on conductive pathways and seismic interpretations of basin/foreland structure are used to reduce non-uniqueness and to test competing structural models.

We then translate the recovered 3D ultramafic geometry into bounded H₂ generation estimates by coupling volume-based metrics with physically realistic limits, including temperature constraints informed by regional geothermal/Curie-depth patterns and process caps imposed by hydrogen solubility and water supply. Spatial comparisons between predicted subsurface H₂-favourable domains and mapped soil-gas anomalies provide a quantitative test of whether surface signals preferentially occur above specific ophiolite blocks and fault systems. The results establish a reproducible template for assessing hydrogen in ophiolite-hosted environments under realistic data availability, supporting evidence-based prioritization of targets in the UAE and across the wider Arabian ophiolite belt.