Comparison of the isotope hydrogeological features of thermal and cold karstic waters in the Denizli Basin (Turkey) and Buda Thermal Karst (Hungary)

Abstract

The isotopic compositions of the Hungarian warm and cold water samples are spread in a wide range along the Global Meteoric Water Line (GMWL), which is a result of the significant change in the climate (mainly temperature) during infiltration (Last Glaciation and Holocene) and of the mixing process along the fault zone. The thermal karst water is isotopically lighter as it was infiltrated in a 7 to 9 °C cooler climate in the Ice Age. However, in the Denizli Basin isotopic composition of all of the thermal, lukewarm and cold waters varies in a relatively narrow range, with the exception of some warm waters whose d18O values have been shifted as a result of water-rock interaction. Isotope data prove that all the waters in the Denizli Basin infiltrated in the Holocene under more or less the same climate, so these waters are young indicating much shorter transit time from the recharge to the discharge areas because of faster flow under the surface or shorter path of the subsurface flow.