Abstract:

Naturally occurring hydrogen（NOH） shows wide distribution and low exploitation costs, highlightens a strong energy potential. Current research lacks a unified and systematic standard for understanding the types of natural hydrogen. Starting from the formation mechanisms of natural hydrogen, this paper categorizes its types, discusses the formation mechanisms of natural hydrogen in China based on the tectonic background, and finally analyzes the hydrogen generation potential in China. The results show that a total of 9 types and 21 chemical processes can form natural hydrogen, including: Primordial deep hydrogen, hydrogen generation from iron-bearing minerals reactions, hydrogen generation from deep fluid evolution and degassing, hydrogen generation processes related to radioactive elements, hydrogen generation during metamorphism, hydrogen generation from rock mechanical fracturing, phosphine hydrolysis, water auto-electrochemical reactions, and the (potential) hydrogen generation mechanism in upper mantle-crust metasomatism. There are natural hydrogen formation mechanisms in three tectonic domains: Plate boundaries (divergent, convergent, and conservative), rift tectonic systems, and cratonic basements; Extensive plate convergence zones, rift basins, and cratonic basements provide the material basis for the formation of natural hydrogen in China; Currently, the discovered natural hydrogen is primarily associated with the serpentinization reaction of ultramafic-mafic rocks, and the hydrogen generation potential of other reaction processes still requires further study.