Origin and Key Enrichment Factors of Helium Resource in the Lower Yangtze Region, Eastern China.

Helium is a critical, scarce, and strategic resource, often found in association with natural gas. This study reports the first discovery of overpressured helium-rich natural gas in the Lower Yangtze Region of Eastern China, with helium concentrations reaching as high as 4.5%, significantly surpassing the commercial extraction threshold of 0.1%. Comprehensive geochemical analyses, including helium isotopes ratios, carbon isotope compositions of CH and CO, and gas compositional data, indicate that the helium in this region is predominantly crustal in origin. This finding contrasts with the mantle-derived helium commonly observed in the Mesozoic and Cenozoic lacustrine rift basins of Eastern China. These results suggest that helium exploration in Eastern China should account for both crustal and mantle-derived sources, challenging previous assumptions that focused primarily on mantle-originated helium. Key geological factors contributing to the observed helium enrichment include: (1) the presence of an ancient Proterozoic granite basement as the primary helium source rock; (2) large and deep fault systems acting as vertical migration pathways; (3) thick gypsum layers functioning as effective caprock seals; and (4) the simple stratigraphic architecture of the central transition belt, which provides favorable conditions for large-scale gas accumulation and preservation. These findings suggest that the central transition belt of the Lower Yangtze Region has significant potential for helium resource development. Future research will prioritize helium reserve estimation and the evaluation of economic extraction feasibility within this area.