 | Supra-subduction zone ophiolites retain hydrogen generation potential after 300 Myr Abstract: The Ural Mountains host well documented natural hydrogen (H2) emissions, yet the Palaeozoic ultramafic complexes are 250–400 Ma old and could have exhausted serpentinisation potential through progressive alteration over geological time. We revisit overlooked Soviet observations from the Kempirsay chromitite district and compare them with recent data from the younger, Jurassic Bulqizë ophiolite in Albania. In both massifs, H2-rich seeps (>80–90 vol. % H2) occur within ∼300 m of podiform chromitite bodies. At Kempirsay, degassing takes place at low temperatures (14–30 °C), and experiments on Kempirsay rocks show that Fe-bearing minerals can generate H2 at near-ambient conditions. New radiocarbon data from Bulqizë methane (apparent age ∼26 ka) demonstrate that associated CH4-H2 inventories are renewed on 104 year time scales. We interpret chromitite bodies and their damage zones as catalytic and hydraulic hubs embedded in a supra-subduction zone ophiolitic architecture that localises serpentinisation and preserves reactive peridotite. This chromitite centred architecture implies that chromitite-bearing mantle slabs can retain hydrogen generation potential for hundreds of millions of years and constitute priority targets for natural hydrogen exploration and stimulated geological hydrogen production. |
<< Previous issue
