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Studying the hydrogeochemical characteristics of hot springs provides essential geochemical information for monitoring earthquake precursors and understanding the relationship between fluids, fractures, and earthquakes. This paper investigates the hydrogeochemical characteristics of hot springs along the Tingri–Nyima Rift (TNR) in southern Tibet, a seismically active zone at the collision front of the Indian and Asian-European plates. The major elements, hydrogen, and oxygen isotopes of seven thermal springs were analyzed from July 2019 to September 2021. The findings indicate that Mount Everest's meteoric water, which has a recharge elevation of roughly 7.5–8.4 km, is the main source of recharge for the hot springs. The water samples have two main hydrochemical types: HCO3-Na and Cl-Na. The temperature of the geothermal reservoir is between 46.5 and 225.4 °C, while the circulation depth is between 1.2 and 5.0 km based on silica-enthalpy mixing models and traditional geothermometers. Furthermore, continuous measurements of major anions and cations at the Yundong Spring (T06) near Mount Everest reveal short-term (8 days) seismic precursor anomalies of hydrochemical compositions before an ML4.7 earthquake 64.36 km away from T06. Our study suggests that seismicity in the northern section of the TNR is controlled by both hydrothermal activity and tectonic activity, while seismicity in the southern section is mainly influenced by tectonic activity. In addition to magnitude and distance from the epicenter, geological forces from deep, large fissures also affect how hot springs react to seismic occurrences. A fluid circulation model is established in order to explain the process of groundwater circulation migration. The continuous hydrochemical monitoring of hot springs near Everest is critical for studying the coupling between hot springs, fractures, and earthquakes, as well as monitoring information on earthquake precursory anomalies near Everest. [ABSTRACT FROM AUTHOR]

• Hydrothermal helium is mainly from radiogenic production in the crust with 7.52 % is mantle derived. • CO 2 is mainly constrained by both decarbonization of Tethyan marine carbonate rocks and mantle fluid. • The He-CO 2 system is constrained by the regional magmatic intrusions and degassing process. • The contrasting slab subduction style and the south boundary of EHS are constrained by helium isotopes. • Location of mantle suture in EHS is extended and the south boundary is also constrained by helium isotopes. While understanding the origins of volatiles has strong implications on heat and tectonic processes, the relationship has not well understood, especially in the Eastern Himalayan Syntaxis (EHS) in the Tibetan Plateau, where tectonic framework, petrologic properties, stress field, and geomorphic water system changes greatly due to the strongest continental collision. Based on samples from warm/hot springs in the EHS, geothermal fluid is sourced from local precipitation and simultaneously recharged by deeply-sourced mantle volatiles. Volatiles from hydrothermal systems are mixture of crustal and mantle origin, in which helium is mainly from radiogenic production in the crust with only up to 7.52% is mantle derived whereas CO 2 is mainly constrained by both decarbonization of Tethyan marine carbonate rocks and mantle volatiles. The helium fluxes are estimated to be almost 1–2 orders higher than some representative volcanically and tectonically active continental regions. The He-CO 2 system is dominantly constrained by the regional magmatic intrusions and hydrothermal degassing process. The boundary of the Indian plate underplating beneath Tibet is extended eastward to across the EHS by evidences from He isotope and this boundary is probably the south boundary of the EHS. Differences of helium isotopes between the EHS and its southeastern region indicate the contrasting slab subduction style in the deep structure. These results present some quantitative constraints for the interpretations of regional tectonic processes on transportation of deeply-sourced volatiles and its indications on continental collision style and present essential basis for understanding volatiles degassing and cycling in the continental collision settings. [ABSTRACT FROM AUTHOR]