Magnetotellurics Point to Serpentinization as a Potential Source of Hydrogen in the Bulqizë Ophiolite

Abstract Hydrogen was first detected in the Bulqizë ophiolite massif (Albania) in 1992, and its origin remains uncertain, with hypotheses ranging from active serpentinization to the release of trapped, fossil H 2 . To constrain the thickness of the ophiolite layer—a key parameter for evaluating hydrogen generation—we conducted a magnetotelluric survey using recording stations located both within and outside the massif. Data processing and subsequent 1D and 2D electrical resistivity models reveal a heterogeneous resistivity distribution, indicating a potential transition from unaltered to progressively serpentinized rocks. The ophiolite thickness is estimated at approximately 6,000 m, and thermal gradients suggest that temperatures may exceed 100°C at depth. These findings imply that regional water inputs could facilitate serpentinization and contribute to hydrogen production, providing important constraints on the geochemical processes occurring within the ophiolite.