Lu, Yi-ChiaYi-ChiaLuWang, ChyiChyiWangSHENG-RONG SONGPEI-LING WANGSong, Ting-JuiTing-JuiSongTaguchi, SachihiroSachihiroTaguchiPeng, Tsung-RenTsung-RenPengLI-HUNG LINLee, Jian-ChengJian-ChengLeeLi, Hong-ChunHong-ChunLi2025-09-052025-09-052025-11https://www.scopus.com/pages/publications/105010861689https://scholars.lib.ntu.edu.tw/handle/123456789/731835The Tatun Volcano Group (TVG), located near the populated Taipei metropolitan area, is a promising geothermal energy source because of its active hydrothermal system. However, severe corrosion from acidic fluids hindered exploration in the 1970s. Given renewed global interest in renewable energy, this study examines the evolution and assesses the reservoir temperatures of neutral thermal fluids to mitigate corrosion-related challenges and facilitate geothermal exploration in the TVG. Water and carbonate samples were collected from hot springs, cores, cuttings, and outcrops along the TVG SW–NE corridor for geochemical analysis. A clumped isotope thermometer was used to calculate carbonate precipitation temperatures, combining stable water isotope analysis (18O and 2H), this approach provides carbonate clumped isotope composition-based reservoir temperatures of 181–276 °C in three areas. Distinct fluid origins and multiple chemical reactions across the depth (temperature) zones were identified. A geothermal model was generated to demonstrate the life cycle of non-strongly acidic fluids, from their deep origins to their upward migration and chemical interactions. Based on water and carbonate analyses, non-strongly acidic zones suitable for geothermal drilling have been identified in the active volcanic region of the TVG. Preliminary drilling data indicate that the vapor-dominated reservoirs in the TVG have significant potential for geothermal exploration and near-term development in conventional geothermal systems. This study further suggests that high-temperature, non-artesian well locations with carbonate deposits, which reflect a history of non-acidic environments, are excellent candidates for future enhanced geothermal systems, advanced geothermal systems, and superhot geothermal resource development.Clumped isotope thermometryGeothermal systemNeutral hot fluidTatun[SDGs]SDG7[SDGs]SDG13[SDGs]SDG14journal article10.1016/j.gexplo.2025.107814