Geochemical characteristics of thermal waters of Hrvatsko zagorje

Abstract

In the region of Hrvatsko zagorje there are a lot of spa localities. The study area is in the northern Pannonian part ofCroatia which is characterized by a high geothermal gradient (0.049 °C/m) and surface heat flow (76 mW/m2). Althoughthere are a lot of thermal occurrences in the study area, only ten were taken into consideration because therewas a lack of geochemical data at other locations. The thermal springs considered are: Harina Zlaka, Krapinske toplice,Tuheljske toplice, Stubičke toplice, Sutinske toplice, Šemničke toplice, Topličica (Mađarevo), Topličica (Gotalovec),Podevčevo, Vraždinske toplice. A compilation of geochemical data from different sources together with ourown measurements has been used in this study. The aim of this paper is to review the thermal waters’ geochemicalcharacteristics and demonstrate how these features can be used to discern their origin and the aquifer they equilibratedwith. The geochemical characteristics of thermal waters of the study area suggest that the water is in equilibriumwith dolomite which means that dolomite is the thermal aquifer in the study area.