Geothermal waters from a 1,100-m-deep geothermal well (No. 7) in the vicinity of Yakedake volcano in Gifu Prefecture, central Japan, were monitored for 1 year for chemical and isotope (D, O, and Sr) composition to examine their source. Drill cuttings from the well and surrounding hot spring waters were also analyzed for ⁸⁷Sr/⁸⁶Sr ratios and chemical composition. Combining the calculated reservoir temperatures for geothermal waters from well No. 7 and the ⁸⁷Sr/⁸⁶Sr ratios obtained, we suggest a shallow source for the geothermal waters, such as the Cretaceous to Paleogene Kasagatake Rhyolites, and propose downward-flowing meteoric waters as dominant at depth where the geothermal waters are enriched in Ca²⁺, K⁺, and Sr²⁺ by the interaction with reservoir rock. The ⁸⁷Sr/⁸⁶Sr ratios of hot spring waters in the Shinhirayu area, west of well No.7, are lower than those in three adjacent areas (Nakao, Gamada, and Hirayu), reflecting differences between the geologic formations comprising the reservoir rocks. The geothermal water from well No. 7 and hot spring waters in the study area are not in chemical equilibrium with the reservoir rocks because the reservoirs are young and not strongly altered.

对日本中部岐阜县八岳岳火山附近1,100米深的地热井（7号井）的地热水进行了为期1年的化学和同位素（D，O和Sr）监测，以检查其地热资源。还分析了来自井水和周围温泉水的钻屑的⁸⁷ Sr / ⁸⁶ Sr比值和化学成分。结合从7号井获得的地热水的计算储层温度和所获得的⁸⁷ Sr / ⁸⁶ Sr比率，我们建议使用浅水来源的地热水，例如白垩纪至古近纪Kasagatake流纹岩，并建议使用向下流动的流水作为在地热水中富含Ca 2 ⁺，K的深度占优势⁺和Sr ^2+是通过与储层岩石的相互作用而产生的。在⁸⁷ SR / ⁸⁶在Shinhirayu区域温泉水的Sr比值，以及7号西，比在三个相邻区域（中尾，Gamada，和平汤）下，反映包含该储集岩的地质构造之间的差异。研究区的7号井的地热水和温泉水与储集层岩石不处于化学平衡状态，因为储层还很年轻并且没有发生强烈变化。