| Abstract |
Selected thermal and mineral waters of Dikili town have been physically divided into three groups; Dikili Spa, Kaynarca and Kocaoba geothermal areas. Thermal and mineral waters, issuing from natural springs and drilling wells, were evaluated from hydrogeological and hydrogeochemical points of view. Origins, mineral saturations, aquifer temperatures, aquifer fluid compositions and aqueous species distributions have been studied by using analytical data of waters. Miocene Yuntda? volcanic-I, which consists of andesitic volcanics, is the oldest unit and occurs as aquifer for aforementioned all the geothermal systems. Overlying Pliocene Demirta? pyroclastics, which are ignimbrite and felsic pyroclastics, cap the systems because of their low permeability values. Quaternary alluvium is the aquifer for cold ground waters. ?18O and ?D data of geothermal waters indicate that they are of meteoric origin and show relatively ?18O enrichment. The measured outlet temperatures of the thermal waters range from 30?C to 99?C. Different geothermometers indicate that reservoir temperatures vary between 120-200?C in the study area. The types of thermal waters are Na-HCO3-SO4, Na-SO4-HCO3 and Na-Ca-SO4 in Dikili Spa, Kaynarca and Kocaoba respectively. Hardness values (oFr) of them are between 3 and 123. Their conductivity values vary between 1900-3200 ?S/cm. Thermal and mineral waters are generally undersaturated with respect to gypsum, quartz, amorphous silica, siderite and fluorite, and oversaturated with respect to calcite, aragonite and dolomite. Mineral equilibrium modelling shows that calcite, aragonite and dolomite scaling problems are expected in product wells during the extraction of thermal and mineral waters in the study area. These waters may cause environmental problems because of their high amount of boron and ion concentrations. Contribution of these waters to surface and ground waters should be prevented after the use of district and greenhouse heating, balneological and thermal tourism purposes. Thus, wastewaters should be re-injected to minimize the negative effects of it to the environment and to feed the geothermal aquifers. |