Geochemical and Geo-thermometers Characteristics of Thermal Groundwater at Khan Ezabeeb Area, in Central Jordan

Abstract

Chemical analysis was conducted of 38 wells discharging thermal fluids in central Jordan near Khan Ezabeeb area. 6 samples of cold water and 7 samples of thermal water were sampled from all over Jordan for comparative analysis; 22 samples and 7 samples were reviewed and studied for stable and radioactive isotope respectively. Chemical characteristics of the thermal fluids were also studied. The data was interpreted by use of WATCH program for speciation and construction of mineral equilibrium diagrams and other graphical representations and classifications. The maximum reservoir temperature for the wells as predicted by calculation of various geo-thermometers exceeds 100°C. There is an evidence of mixing with cold water.  The thermal fluids are of bicarbonate type with two main aquifers and the reservoir rocks were mainly marly and cherty limestone. The calculated Quartz and Chalcedony geo-thermometer values for the geothermal well waters indicate reservoir temperature of 60°–80°C’ the Na-K-Ca geo-thermometers give mostly higher values; however, calculation of mineral saturation for the geothermal water shows fluid from some wells to be close to the equilibrium at 115°C and some degree of under saturation with anhydrite, fluorite and chalcedony. The chemical composition of the waters in the studied area was governed by water rock interaction in this study the Cl-SO₄-HCO₃, Na- K- Mg triangular diagrams, and stable isotopes were used to classify the geothermal and cold waters and to study some processes in the geothermal system. The geothermal waters are bicarbonate type with some samples of chloride and sulfide - indicating reactions with sedimentary rocks (sandstone). Origins of the fluids are of meteoric water and the age dated between 20,000 years up to 38,000 years.

Keywords: Geochemical, Geo-Thermometers, Thermal Fluids, Age Determination, Khan Ezabeeb, Jordan.