Abstract: Origins of spring waters in southeastern Gansu province and the relationship between the geochemical variation and the 2008 Wenchuan M_{S8.0 earthquake were discussed based on the hydrochemical and isotopic data. The total dissolved solids (TDS) of water samples of seven springs(Tongwei Tangchihe spring, Qingshui station, Tianshui station, Wushan station, Wushan 22th well, Chengxian station, Wudu station) ranged from 241.7 mg/L to 2372.1 mg/L. The spring water can be classified into four chemical types (Na·Ca-SO4、Ca·Mg-SO4、Na-HCO3·SO4、Ca·Mg-SO4·HCO3). Chemical types of the waters were related to fault depths and the lithology of surrounding rocks. The TDS was in positive correlation with fault depths in general. Values of δ¹⁸O and δD for Tongwei Tangchihe spring and Wudu station were in the range of -11.4‰ ~ -7.6‰ and -85.7‰ ~ -57.1‰ respectively, and the ³He/⁴He values of water samples were 0.4×10^-7 and 12.7×10^-7, respectively. The isotope characteristics indicate that those spring waters were originated from atmospheric precipitation followed by interaction between water and rock during circulation with a probable mix of earth’s surface water. The concentration of K⁺, Ca²⁺ increased and concentration of SO^2-4, Cl^- decreased in general while the amount of Na⁺ changed unremarkably after the break of 2008 Wenchuan MS8.0 earthquake, and the depths of hot water circulation were altered because of the earthquake. In this article, the sources of springs in southeast of Gansu province, origins of water chemistry types and its relationship with MS8.0 earthquake in Wenchuan are determined.}

Key words: Fluid geochemistry, Hot spring, Ion concentration, Isotope