Natural hydrogen (H 2 ) is also known as gold H 2 and is a carbon-free energy resource with potential exploitation and utilization due to its renewable, environmentally friendly, and cost-effective characteristics. In numerous shallow depressions with circular and oval shapes, seep gases have been found with H 2 concentrations of tens to more than a thousand parts per million (ppm), which highlights the potential for underground H 2 resources. This has accelerated the exploration for natural H 2 , and many energy companies in the United States, United Kingdom, Australia, France, and Brazil have developed exploration plans. Academician Jin Zhijun and his team discovered high-concentration H 2 leakage with a maximum value of 6948 ppm in the Sanshui Basin for the first time. The related results have been published in Science Bulletin .
The Sanshui Basin is a rift basin that developed on the continental margin of South China during the Late Cretaceous to Miocene. The lithosphere beneath the basin is the thinnest in mainland China. Academician Jin Zhijun and his team conducted extensive fieldwork, and soil-gas measurements and sampling with portable gas analyzers for H 2 , CO 2 , and Rn in the Sanshui Basin. The results show that anomalously high concentrations of H 2 occur in multiple fault zones, with high 222 Rn and CO 2 anomalies. The chemical and H–C isotopic compositions of the soil gas were determined in the laboratory. Academician Jin considered that the H 2 concentration anomalies in the soil gas reflect seepage of H2 from deep levels. Based on the geological context and geochemical features of soil gas in the Sanshui Basin, he proposed the detected H 2 may be related to magmatic degassing, serpentinization and thermal degradation. Deep extensional faults and small faults distributed along the main faults in the basin are ideal channels for H 2 ascent. The small size of the H 2 molecule enables rapid diffusion. To find economic H 2 reservoirs, favorable storage conditions are crucial. Salt formation with an overall thickness of 70–120 m in the Sanshui Basin are located in the third member of the Paleogene Buxin Formation. He speculated that the low-porosity and low-permeability, dense salt rocks in the Buxin Formation of the Sanshui Basin may be a high-quality cap rock for H 2 accumulation.
Academician Jin proposed a source–transport–capture model to guide H 2 exploration, which includes the three critical elements for a H 2 accumulation system: (1) sources that generate H 2 ; (2) faults that connect H 2 sources; and (3) traps that accumulate H 2 . He speculated seepage of high concentrations of H 2 in the Sanshui Basin may indicate the existence of a vast accumulation or a continuous source of H 2 . Therefore, the traps in the Sanshui Basin, which are connected to deep faults and covered by salt cap rocks, are likely favorable locations for H 2 accumulation and exploration. In addition, he proposed that rift basins that have experienced mantle upwelling and crustal thinning, such as the Bohai Bay, Songliao, Sanshui, and Subei basins, are favorable areas for H 2 exploration.
Science Bulletin