中国东部含幔源氦流体分布特征及运聚富集规律认识OA

Mantle-derived helium is a primary type of helium,but so far,its migration,enrichment and accumulation mechanisms have not been systematically studied.In this paper,the existing research findings are reviewed.Then,focusing on the eastern China,the spatio-temporal distribution patterns,occurrence characteristics,and migration and accumulation processes of mantle-derived helium are analyzed to clarify the coupling relationships between shallow accumulation and deep dynamics of mantle-derived helium in different areas,identify the factors controlling helium enrichment,and provide a new idea for the development of helium resources in China.The following results are obtained.First,the mantle-derived helium-bearing fluids in the eastern China are primarily distributed in Cenozoic rift-fault basins and volcanic activity belts,exhibiting significant spatio-temporal zoning.In the north,mantle-derived helium is enriched along the Tan-Lu fault zone,while in the south,it is concentrated in fault zones and diapiric areas at the boundaries between uplifts and depressions.Second,mantle-derived helium often occurs as oil and gas reservoir associated helium or as water-soluble helium in natural gas reservoirs or groundwater,and its 3He/4He ratio is significantly different from that of mantle endmembers.The average contribution rate of mantle-derived helium in helium-rich gas reaches 66.7%,with peak value exceeding 90.0%.Furthermore,the mineralization,dissolution,and precipitation of CO2 can significantly promote local helium enrichment.Third,Pacific plate subduction,lithospheric thinning,and discordogenic fault network are the core driving forces for the migration and accumulation of mantle-derived helium.The release mechanism of mantle-derived helium is controlled by mantle melting and magmatic degassing,while mineral-fluid reaction represents a critical enrichment effect of mantle-derived helium.In conclusion,the enrichment of mantle-derived helium in the eastern China is controlled by multi-scale geological processes ranging from the deep crust and mantle to shallow basins,and the proposed helium enrichment model of"deep-source and shallow-accumulation,macro-source and micro-accumulation"can provide an essential theoretical support for enhancing China's self-sufficiency in helium resources.