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The Kesenozu thermal springs are located in northwestern Turkey, about 10 km south of Seben. The springs emerge from a fracture zone created by strike-slip faulting that strikes north–northwest, along the Hamambogazi Creek, in northwestern Anatolia. The reservoir comprises a steeply dipping fracture zone and deep, feeding aquifers hosted by limestones and conglomerates of the Kesenozu Formation. Eight springs and one shallow well discharge thermal water at a total rate of about 44 l/s with temperatures between 42 and 78 °C. The waters are of neutral pH, NaHCO3 type. The meteoric origin of the spa waters is evident from their chemical and isotopic (18O, 2H, 3H) compositions. The thermal system is driven by deep-reaching advective flows where rainwater becomes heated on descent, and after deep paths ascend along fractures that act as hydrothermal conduits. It can be described as an advective geothermal system. Silica (chalcedony) geothermometry indicates equilibrium temperatures between 89 and 94 °C. A recently drilled deep well encountered similar temperatures at about 2 km depth. The minimum heating power potential (direct use) of the fracture zone reservoir is about 10 MWth.

The Kozakli-NevAYehir geothermal field extends a long a NW-SE direction at SE of the Centrum of Kozakli. The area is not rugged and average elevation is 1,000 m. The Kozanozu Creek flows towards north of the area. In the Kozakli thermal Spa area, thermal waters are manifested along a valley with a length of 1.5 km and 200 m width. In this resort some hot waters are discharged with no use. The thermal water used in the area comes from wells drilled by MTA. In addition, these waters from wells are also utilized by hotels, baths and motels belonging to City Private Management, Municipality and private sector. The measured temperature of Kozakli waters ranges from 43-51A degrees C in springs and 80-96A degrees C in wells. Waters are issued in a wide swampy area as a small group of springs through buried faults. Electrical conductivity values of thermal spring and well waters are 1,650-3,595 mu S/cm and pH values are 6.72-7.36. Kozakli cold water has an electrical conductivity value of 450 mu S/cm and pH of 7.56. All thermal waters are dominated by Na+ and Cl-SO4 while cold waters are dominated by Ca+2 and HCO3 (-). The aim of this study was to investigate the environmental problems around the Kozakli geothermal field and explain the mechanisms of karstic depression which was formed by uncontrolled use of thermal waters in this area and bring up its possible environmental threats. At the Kozakli geothermal field a sinkhole with 30 m diameter and 15 m depth occurred in January, 17th 2007 at the recreation area located 20 m west of the geothermal well which belongs to the government of NevAYehir province. The management of the geothermal wells should be controlled by a single official institution in order to avoid the creation of such karstic structures affecting the environment at the source area.

The Terme and Karakurt thermal resorts are located in the center of KirAYehir city in central Anatolia. Thermal waters with temperatures of 44-60A degrees C are used for central heating and balneologic purposes. Paleozoic rocks of the KirAYehir Massif are the oldest units in the study area. The basement of the Massif comprises Paleozoic metamorphic schist and marbles which partly contain white quartzite layers of a few tens of cm thickness. The metamorphic schists which are cut by granites of Paleocene age are overlain by horizontally bedded conglomerate, sandstone, claystone, and limestone of upper Paleocene-Eocene age. Among the thermal and cold waters collected from the areas of Terme and Karakurt, those from thermal waters are enriched with Ca-HCO3 and cold waters are of Ca-Mg-HCO3 type waters. The pH values of samples are 6.31-7.04 for the thermal well waters, 6.41 for thermal spring, 7.25 and 7.29 for the cold waters, and 7.52 for the Hirla lake water. EC values are 917-2,295 mu S/cm for the thermal well waters, 2,078 mu S/cm for thermal spring, and 471 and 820 mu S/cm for the cold springs. The lowest TDS content is from water of T10 thermal well in the Terme area (740.6 mg/l). The hot and cold waters of Terme show very similar ion contents while the Karakurt hot waters at western most parts are characterized by distinct chemical compositions. There is ion exchange in thermal waters from the T5 (5), T6 (6), T12 (7), and T1 (8) wells in the Terme area. The thermal waters show low concentrations of Fe, Mn, Ni, Al, As, Pb, Zn and Cu. Waters in the study area are of meteoric origin, and rainwater percolated downwards through faults and fractures, and are heated by the geothermal gradient, later rising to the surface along permeable zones. delta C-13(VPDB) values measured on dissolved inorganic carbon in samples range from -1.65 to +5.61aEuro degrees for thermal waters and from -11.81 to -10.15aEuro degrees for cold waters. Carbon in thermal waters is derived from marine carbonates or CO2 of metamorphic origin while carbon in cold waters originates from freshwater carbonates.

The Hamambogazi spa in western Turkey was built around natural hot springs with discharge temperatures in the range of 30–54°C; the waters have near neutral pH values of 6.50–7.10 and a TDS content between 2,694 and 2,982 mg/l. Thermal water with a temperature of 47.5–73°C has been produced at 325 l/s from five wells since 1994, causing some springs to go dry. A management plan is required in the study area to maximize the benefits of this resource, for which currently proposed direct uses include heating in the district and greenhouses, as well as balneology in new spas in the area. The best use for the water from each spring or well will depend on its temperature, chemistry and location. The thermal waters are mixed Na–Mg–HCO3–SO4 fluids that contain a significant amount of CO2 gas. The chemical geothermometers applied to the Hamambogazi thermal waters yield a maximum reservoir temperature of 130°C. Isotope results (18O, 2H, 3H) indicate that the thermal waters have a meteoric origin: rainwater percolates downward along fractures and faults, is heated at depth, and then rises to the surface along fractures and faults that act as a hydrothermal conduit. The basement around the Banaz Hamambogazi resort is comprised of Paleozoic metamorphic schist and marbles exposed 8 km south and 15 km north of Banaz. Mesozoic marble, limestone and ophiolitic complex are observed a few km west and in the northern part of Banaz. These units were cut at a depth of 350–480 m in boreholes drilled in the area. Overlying lacustrine deposits are composed of fine clastic units that alternate with gypsum, tuff and tuffites of 200–350 m thickness. The marble and limestones form the thermal water aquifer, while lacustrine deposits form the impermeable cap.

The Oylat spa is located 80 km southeast of Bursa and 30 km south of Inegol in the Marmara region. With temperature of 40°C and discharge of 45 l/s, the Oylat main spring is the most important hot water spring of the area. Southeast of the spa the Forest Management spring has a temperature of 39.4°C and discharge of 2 l/s. The Goz spring 2 km north of the spa, which is used for therapy of eye disease, and cold waters of the Saadet village springs with an acidic character are the further important water sources of the area. EC values of Main spring and Forest Management hot spring (750–780 μS/cm) are lower than those of Saadet and Goz spring waters (2,070–1,280 μS/cm) and ionic abundances are Ca > Na + K > Mg and SO4 > HCO3 > Cl. The Oylat and Sizi springs have low Na and K contents but high Ca and HCO3 concentrations. According to AIH classification, these are Ca–SO4–HCO3 waters. Based on the results of δ18O, 2H and 3H isotope analyses, the thermal waters have a meteoric origin. The meteoric water infiltrates along fractures and faults, gets heated, and then returns to surface through hydrothermal conduits. Oylat waters do not have high reservoir temperatures. They are deep, circulating recharge waters from higher enhanced elevations. δ13CDIC values of the Main spring and Forest Management hot spring are −6.31 and −4.45‰, respectively, indicating that δ13C is derived from dissolution of limestones. The neutral pH thermal waters are about +18.7‰ in δ34S while the sulfate in the cold waters is about +17‰ (practically identical to the value for the neutral pH thermal waters). However, the Goz and Saadet springs (acid sulfate waters) have much lower δ34S values (~+4‰).