Hong Zhibin¹, Wang Xiaofeng¹, Li Xiaobin², Wang Zuodong², Wu Dahuan³, Liu Yongchao¹, Zhao Dong⁴, Chen Keyu¹, Zhang Dongdong¹, Liu Wenhui¹

(¹State Key Laboratory of Continental Evolution and Early Life, Northwest University, Xi’an, Shaanxi 710069, China;²Institute of Eco-Environmental Resources, Northwest CAS, Oil & Gas Resources Center, Lanzhou, Gansu 730000, China;³South Fujian Geological Party, Zhangzhou, Fujian 363000, China;⁴School of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, China)

Abstract: Deep fluids serve as a critical link between deep Earth geodynamic processes and the surficial geological environment. Against the backdrop of Pacific plate subduction and lithospheric thinning, Eastern China exhibits pronounced geothermal anomalies and active deep degassing. Due to its unique physicochemical properties and the stark contrast between crustal and mantle isotopic signatures, helium is the most sensitive tracer for mantle-derived contributions. By systematically analyzing the geochemical characteristics of helium and its associated carrier gases in hot spring volatiles from representative geothermal areas across Eastern China, this study explores the migration patterns and enrichment mechanisms of mantle-derived helium. Our findings reveal significant spatial heterogeneity in helium isotopic compositions, with mantle-derived contributions varying drastically across different tectonic units; specifically, the Late Cenozoic volcanic zones in Northeast China exhibit exceptionally high mantle helium fractions due to direct asthenospheric degassing, while deep-seated fault systems like the Tan-Lu Fault Zone facilitate the advective transport of deep volatiles despite the absence of recent volcanism. In contrast, the Southeastern Coastal Extension Belt displays distinctive crust-mantle fluid mixing under high heat flow, with significant mantle input observed near NE-striking faults. Furthermore, the negative correlation between CO₂/³He ratios and total helium concentrations observed across almost all sampled sites. This trend indicates that the preferential removal of CO₂ through mineral carbonation during hydrothermal circulation, acts as a fundamental driver for the secondary enrichment of helium. As CO₂ is stripped from the ascending fluid phase, the relatively inert helium becomes progressively concentrated, particularly along long-distance migration pathways in fault-controlled systems. In conclusion, this study demonstrates that the geochemical signatures of mantle-derived helium in Eastern China are synergistically controlled by the intensity of lithospheric thinning, the permeability of crustal-scale faults, geothermal anomalies and the coupling processes between helium and its carrier gases. These insights provide a quantitative framework for evaluating the formation of high-concentration helium resources in tectonically active regions.

Keywords: Eastern China, mantle-derived helium, release variation, enrichment mechanism

Author Profile:

Hong Zhibin, Male, PhD Candidate, mainly engaged in helium enrichment mechanism research. E-mail: 202410418@stumail.nwu.edu.cn