A conceptual model for groundwater flow and geochemical evolution of thermal fluids at the Kizilcahamam geothermal area, Galatian volcanic Province

Ktzticahamam geothermal area is one of the most important geothermal fields in the Galatean Volcanic Province northern Central Anatolia of Turkey. Kizilcahamam geothermal field is liquid-dominated system that have been developed in the rugged terrain, and usually consists of a geothermal systems that occur commonly associated with terrestrial volcanism. This field is characterized by thermal and mineralized springs, travertine, with wide alteration zones. Thermal waters are issue through the faults and fracture zones of the volcanics. The temperatures of the wells in the Kizilcahamam town center varies between 42 and 81 degrees C, whereas the temperature of thermal and mineralized water springs in the area of Actsu Stream and Seyhamam varies between 23 and 43 degrees C. Electrical conductivity values for thermal waters are between 1029 and 3700 mu S/cm. Thermal waters in Kizticahamam area are mainly Na-HCO3-Cl and Na-Ca-HCO3 type, with high salinity, while cold groundwater is mostly of Ca (Na, Mg)-HCO3 type, with lower salinity. Both waters of Kizdcahamam town center and Actsu Stream appear to be derived from a deeper reservoir fluid, whereas Seyhamam thermal waters are compatible with shallow cold waters heated by steam absorbing high temperatures. High contents of some minor elements in thermal waters, such as F, B, Li, Rb, Sr and Cs probably derive from enhanced water rock interaction. The isotopic values of thermal water (delta O-18, delta H-2, delta H-3) indicates their deep-circulating meteoric origin and allow estimation of infiltration altitude ranging between 1350 and 1750 m.a.s.l.This datum, supported by structural data, suggests the Isikdag and Alucclag Mountains as the recharge area of the system. As frequently observed in many geothermal systems positive O-18 shifts of Kizilcahamam thermal waters relative to the local meteoric line were considered to be primarily due to interaction with host rocks at elevated temperature (T > 150 degrees C) and from CO2 exsolution of thermal and mineral springs. In this system, geothermal waters are heating by an intrusive-cupola and geothermal gradient, followed by the waters rising to the surface along faults and fractures that act as hydrothermal conduits. A conceptual hydrogeochemical model was developed for a hydrogeological flow system in the Kadcahamam Region.