Hydrogeochemical and Isotopic Characteristics of the Hot Springs in the Litang Fault Zone, Southeast Qinghai–Tibet Plateau

Round 1

Reviewer 1 Report

The aim of the study is to obtain the hydrogeochemical characteristics of hot  spring water in the Litang fault zone, and to establish a conceptual model to discuss the process of ground fluid circulation, and the relationship between ground fluid circulation and earthquakes occurred in the fault zone.

The paper appears well-structured; however, some sections must be improved.  Therefore, I believe

the manuscript should be published only after major revision.

Comments (R = row#):

R=186: Statistical characteristics could be better described using box plots

R= 278: the authors write: according to Shchukarev classification….. (insert a reference biblio)

R=284: To evaluate the chemical composition of the water it is not enough to use the Piper diagram because it does not take into account (as proposed by the authors) salinity, I suggest using a TIS salinity diagram, as proposed by:

Apollaro, C.; Vespasiano, G.; De Rosa, R.: Marini L. Use of mean residence time and flowrate of thermal waters to evaluate the volume of reservoir water contributing to the natural discharge and the related geothermal reservoir volume. Application to Northern Thailand hot springs. Geothermics 2015, 58, 62-74

R=301: The authors write: This phenomenon indicates that the cation exchange is an important process that controls hydrochemical features……. This diagram alone is not sufficient to describe the exchange phenomena. Insert a diagram with CAI data. See for example the work:

Peng, Chen, Yuanming Liu, Huiyu Chen, Qiaowei Yuan, Qingzhi Chen, Shilong Mei, and Zhonghu Wu. "Analysis of Hydrogeochemical Characteristics of Tunnel Groundwater Based on Multivariate Statistical Technology." Geofluids 2021 (2021).

R=316: In the diagram of figure 5 the colors of the symbols are different for the same areas in figure a and in figure b. example Maoya, in figure a it is green, while in figure b it is blue!

R=487: Given the presence of carbonate rocks, it might be useful to compare the results of the geothermometer with the Ca/Mg proposed by Chiodini et al., 1995

R=530:  Which database was used?

R=546: In calculating the saturation index with dolomite, which mineral was used? Ordered or Disordered? Consult this work to understand the differences:

Apollaro, C., Caracausi, A., Paternoster, M., Randazzo, P., Aiuppa, A., De Rosa, R., Fuoco, I., Mongelli, G., Muto, F., Vanni, E. and Vespasiano, G., 2020. Fluid geochemistry in a low-enthalpy geothermal field along a sector of southern Apennines chain (Italy). Journal of Geochemical Exploration, 219, p.106618.

Furthermore,  It could be useful to improve discussion with further diagrams such as Cl vs 18O and Cl vs. D or others mobile costituent. Mobile constituents help comprehension about relationships and evolutions of systems. In this case, to improve knowledge about mixing between different sources.

Discussions and conclusions need to be rewritten taking into account previous comments

ADD THESE REFERENCES

Apollaro C., Vespasiano G., Muto F., De Rosa R., Barca D. & Marini L. (2016): Use of mean residence time of water, flowrate, and equilibrium temperature indicated by water geothermometers to rank geothermal resources. Application to the thermal water circuits of Northern Calabria. Journal of Volcanology and Geothermal Research.  328, 147–158

Chiodini, G., Frondini, F. and Marini, L. (1995). Theoretical geothermometers and 761 pCO2 indicators for aqueous solutions coming from hydrothermal systems of 762 medium-low temperature hosted in carbonate-evaporite rocks. Application to the 763 thermal springs of the Etruscan Swell. Italy. Applied Geochemistry, 10, 337-346.

Apollaro, C., Caracausi, A., Paternoster, M., Randazzo, P., Aiuppa, A., De Rosa, R., Fuoco, I., Mongelli, G., Muto, F., Vanni, E. and Vespasiano, G., 2020. Fluid geochemistry in a low-enthalpy geothermal field along a sector of southern Apennines chain (Italy). Journal of Geochemical Exploration, 219, p.106618.

Peng, Chen, Yuanming Liu, Huiyu Chen, Qiaowei Yuan, Qingzhi Chen, Shilong Mei, and Zhonghu Wu. "Analysis of Hydrogeochemical Characteristics of Tunnel Groundwater Based on Multivariate Statistical Technology." Geofluids 2021 (2021).

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors,

Please see attachment file.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Remarks from  reviewers have been correctly addressed, and the paper is now more focuse on his core topic
In my opinion it is now acceptable.
Best regards

Reviewer 2 Report

 Manuscript has been sufficiently improved to warrant publication in Water.