Isotope and chemical compositions of thermal fluids at Tekman Geothermal Area (Eastern Turkey)

Abstract

The aim of this study was to understand geochemistry of thermal fluids circulating in the basin at the southwest of Tekman (Erzurum, Turkey) Geothermal Province in Eastern Anatolia as well as to estimate reservoir temperature and its heat source by assessment of helium and carbon isotopic compositions of liquid and gas samples.Deep thermal and cold shallow groundwaters are NaCl type (Cerme and Ilipinar springs) and Ca-Mg-HCO 3 type, respectively. The discharge temperatures of thermal waters vary between 29 and 57°C. The reservoir temperatures were estimated by solute silica and cation geothermometers vary from 80 to 110°C. CO 2 is the dominant gas in geothermal fluids with variable amounts of nitrogen, helium and CH 4 . The isotopic ratios of helium that range from 1.03 to 1.54Ra c show a range crustal to magmatic-type values. The isotopic composition of carbon (CO 2 ) obtained from the bubbling and dissolved gases shows the variation from -0.2 to 3.4‰ vs. PDB. The mantle derived fluids interact at shallower levels with circulating meteoric waters and originate geothermal systems from which equilibration temperatures were estimated up to 192°C by gas geothermometers.

The Local Earthquake Tomography of Erzurum (Turkey) Geothermal Area

“…It is emphasized that the geothermal potential of the region in the geochemical studies carried out in Erzurum and its surroundings (Bayraktutan et al 1996;Yuce and Taskiran 2013;Kilic and Inceoz 2015;Kaygusuz et al 2018). Bayraktutan et al (1996) reported signs belonging to the hot spring water in the studies carried out on active faults in Erzurum and its surroundings.…”

“…Bayraktutan et al (1996) reported signs belonging to the hot spring water in the studies carried out on active faults in Erzurum and its surroundings. Yuce and Taskiran (2013) found that the thermal waters had deep mantle traces and these waters were magmaic based, as a result of the analysis of gas and water samples taken from thermal waters with the temperature of 57 degrees. Kaygusuz et al (2018) reported that magmatic materials were transported along active tectonic units in the study carried out by Kandilli and its vicinity.…”

“…Moreover, there are some attempts associated with geothermal potential (Bektas et al 2007;Gulec and Hilton 2016), geochemical (Bayraktutan et al 1996;Keskin e al. 1998;Italiono et al 2013;Yuce and Taskiran 2013;Kilic and Inceoz 2015;Gulbay 2015;Kaygusuz et al 2018) and petroleum (Oruc et al 2013) features of the area. In recent years, there are several seismological studies for the Eastern part of Turkey such as: Maden and Ozturk (2015), Ozturk (2015;2017;2018) and these studies are very important in the evaluation of seismotectonic properties of the Eastern Anatolian region.…”

Geochemical and Isotopic Compositions and Geothermometry of Thermal Waters in the Magumsan Area, South Korea

“…The low Mg content of thermal waters can be explained by the absorption of Mg in high-temperature geothermal systems. As the geothermal fluids flow from a high temperature to a low temperature environment, it appears to adsorb large amounts of Mg into contacting host rocks [13,18]. The occurrence of Mn in thermal water might be due to the dissolution of secondary Mn-bearing minerals that are associated with epithermal activity.…”

“…Chemical compositions of the groundwaters (MG) are of the Ca-HCO 3 type, whereas the thermal waters (MH) can be chemically divided into a Na-HCO 3 type at lower temperatures (type I) and an Na-Cl (HCO 3 − , SO 4 2− ) type at higher temperatures (type II). It is generally considered that, in the geochemical evolution of thermal waters and deep groundwater in granite and gneiss areas of South Korea, the waters are of the Ca-HCO 3 type initially, progressing through the Ca(Na)-HCO 3 type to the alkaline Na-HCO 3 type in the final stage [13,19]. The two different types of thermal water appear to have evolved in different geological environments.…”