Stable Isotope Evaluation of Geothermal Gases from the Kızıldere and Tekke Hamam Geothermal Fields, Western Anatolia, Turkey
Round 1
Reviewer 1 Report
The manuscript entitled “Stable Isotope Evaluation of Geothermal Gases from the Kızıldere and Tekke Hamam Geothermal Fields, Western Anatolia, Turkey” (geosciences-2003566) by Süer et al. is very interesting paper discussing chemical and isotopic composition of volatiles in geothermal fluids in western Turkey.
The study area, Kizildere geothermal field, hosts the first geothermal power plant installed in Turkey and thermal fluids in this area have been investigated in several studies by means of isotope and water chemistry, geothermometry, and fluid-mineral equilibria. However, the manuscript by Süer et al. is a pioneering study on isotope evaluation of geothermal gases from the Kizildere and Tekke Hamam fields.
The methods and assessment presented in the paper are quite sufficient to achieve the aim of study. In the paper, authors used several isotope mixing diagrams to delineate the source of the fluids and identify the possible physicochemical processes that alter the initial fluid composition within the subsurface and during their ascent to the surface. As a conclusion, I would recommend acceptance of the manuscript for the Special Issue: Geogases in Fault Zones in the journal of Geosciences.
Author Response
- The manuscript was spell checked.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript focus on evaluation of stable isotopes in volatile geothermal gases. In the study all gas samples from Kızıldere and Tekkehamam were collected in September and November 2007. 13-C, 2-H and 15-N isotopic ratio in CO2, CH4 and N2 from gas samples from Kızıldere and Tekkehamam Geothermal Fields. This study indicate that CO2 is limestone origin and not organic origin according to CO2/He and 13-Carbon ratios.Also the study show that geothermometer temperatures too much higher than wellhead temperature acording to CO2-CH4 isotopic geothermometer in Kızıldere Geothermal Field. However hydrcarbon composition geothermometer gives a bit higher than wellhead temperate. It is signed that 13-Carbon in CO2 and ratio CO2/He put out that a dominant limestone source and an accompanying minor magmatic component in gas samples from both Kızıldere and Tekkehamam in the manuscript. In this manuscript estimated temperatures according to CO 2 -CH 4 isotope geothermometer were indicated temperatures 20–40 °C higher than wellhead temperature at Tekke Hamam and 100–160 °C higher than wellhead temperature at Kızıldere. The manuscript will contribute to science as great. Thanks to authors for their efforts.
Comments for author File: 
Comments.pdf
Author Response
- A detailed diagram showing the main geological framework of the Tekke Hamam and Kızıldere geothermal fields was inserted into Figure 1 (C).
- In Table 1, C1, C2 and C3 was replaced by CH4, C2H6 and C3H8, respectively.
- The sample names from both fields were inserted into Figure 2-3-4 and 5, near their respective symbols.
- In the caption of Figure 6, a short explanation was added regarding the air saturated water.
- The reservoir temperature representative for Tekke Hamam geothermal field was inserted into the text in section 4.6 (Reservoir Temperature Evaluation).
Author Response File: Author Response.docx
Reviewer 3 Report
Dear authors, I have read this text carefully. In my opinion, it is written correctly.
However, I have a suggestion about the structure of the manuscript, since in the whole 18-page article only basically 1 page of results with a table. Maybe it would be useful to move some of the data from the discussion to the results, or combine the results with the discussion?
Author Response
- The Results and Discussion parts of the manuscript were combined and the section numbers were modified.
Author Response File: Author Response.docx
