Mixing processes in hydrothermal spring systems and implications for interpreting geochemical data: a case study in the Cappadocia region of TurkeyProcessus de mélanges dans des systèmes de sources hydrothermales et implications pour l’interprétation de données géochimiques: un cas d’étude dans la région du Cappadoce en TurquieProcesos de mezcla en sistemas de manantiales hidrotermales e implicancia para la interpretación de datos geoquímicos: un caso de estudio en la región de Capadocia de Turquía热水泉系统中混合过程及解译地球化学资料的启示:土耳其Cappadocia地区研究实例Processos de mistura em sistemas de nascentes hidrotermais e implicações para a interpretação de dados geoquímicos: um caso de estudo na região da Capadócia, na Turquia Sıcak su kaynak sistemlerinde karışım süreçleri ve sonuçlarının jeokimyasal verilerle yorumlanması: Kapadokya bölgesi örnek çalışması, Türkiye

Mixing is a dominant hydrogeological process in the hydrothermal spring system in the Cappadocia region of Turkey. All springs emerge along faults, which have the potential to transmit waters rapidly from great depths. However, mixing with shallow meteoric waters within the flow system results in uncertainty in the interpretation of geochemical results. The chemical compositions of cold and warm springs and geothermal waters are varied, but overall there is a trend from Ca–HCO3 dominated to Na–Cl dominated. There is little difference in the seasonal ionic compositions of the hot springs, suggesting the waters are sourced from a well-mixed reservoir. Based on δ18O and δ2H concentrations, all waters are of meteoric origin with evidence of temperature equilibration with carbonate rocks and evaporation. Seasonal isotopic variability indicates that only a small proportion of late spring and summer precipitation forms recharge and that fresh meteoric waters move rapidly into the flow system and mix with thermal waters at depth. 3H and percent modern carbon (pmC) values reflect progressively longer groundwater pathways from cold to geothermal waters; however, mixing processes and the very high dissolved inorganic carbon (DIC) of the water samples preclude the use of either isotope to gain any insight on actual groundwater ages.