Geochemical studies documented the composition of ultra-fresh thermal water in the Fazenda Giráu, near Itabira (Minas Gerais state, Brazil) for the first time. The studied water is characterized by temperature of 35 °C, very low electric conductivity (approx. 20 μS/cm), uncommon Mg–Ca–HCO₃–NO₃ hydrochemical type, and an elevated radon concentration (about 500 Bq/L). The presence of tritium suggests the modern age of studied water, contained in highly resistant quartzite-dominated aquifer rocks. Application of a geothermometric approach gave an estimation of the equilibrium temperature in the geothermal system at about 42 °C. Inverse geochemical modelling quantified water-rock reactions responsible for the observed groundwater chemistry. Decomposition of soil organic matter and decay of primary (feldspars, biotites, muscovite) and secondary (montmorillonites, illite) aluminosilicate minerals accompanied by kaolinite and gibbsite formation are the dominant processes forming chemical composition of water. The investigated water has balneotherapeutic potential due its elevated temperature and high concentrations of radon and silicic acid.

地球化学研究首次记录了伊塔比拉（巴西米纳斯吉拉斯州）附近的 Fazenda Giráu 超新鲜热水的成分。所研究的水的特点是温度为 35 °C，电导率非常低（约 20 μS/cm），不常见的 Mg-Ca-HCO ₃ -NO ₃水化学类型，氡浓度升高（约 500 Bq/L）。氚的存在表明研究水的现代时代，包含在以石英岩为主的高抗性含水层岩石中。地热测量方法的应用估计了大约 42 °C 的地热系统中的平衡温度。逆地球化学建模量化了负责观察到的地下水化学的水岩反应。土壤有机质的分解和原生（长石、黑云母、白云母）和次生（蒙脱石、伊利石）铝硅酸盐矿物伴随高岭石和三水铝石的形成是形成水化学成分的主要过程。由于其高温和高浓度的氡和硅酸，所研究的水具有浴疗潜力。