Hydrothermal Fluids and Cold Meteoric Waters along Tectonic-Controlled Open Spaces in Upper Cretaceous Carbonate Rocks, NE-Iraq: Scanning Data from In Situ U-Pb Geochronology and Microthermometry
Round 1
Reviewer 1 Report
The Upper Cretaceous carbonates in Harir-Spelek Basin along the Zagros Thrust-Fold Belt experienced extensive hot brine fluids that produced several phases of hydrothermal cements, but the interpretation of these fluids remains controversial and fundamental questions remain unanswered. In this study, the authors studied fluid inclusion petrography and microthermometry, dolomite and calcite cements LA-ICP-Ms U-Pb dating, together with published data of oxygen and carbon isotopes, thus revealed paleo-temperatures and paleo-salinities of the dolomitizing fluids and determine the pulse chronology and their possible sources. The study found that 1) two fluid entrapment episodes with different formation temperatures and 2) two fluid migrations possibly occurred during the Late Cretaceous and Pliocene times, respectively. This study proposed insightful views for discussion of fluid evolution of the Upper Cretaceous carbonates in Harir-Spelek Basin, which is favorable for publication in Water subject to Moderate revision as I noted in the annotated PDF file.
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 1 Comments
First of all, I would like to express my grateful to the 1st Reviewer for his strong contribution in revising the manuscript in details, and below kindly find the answer to all his/her comments and suggestions:
Point 1: Font style difference between this paragraph and the latter (Abstract).
Response 1: font style are modified accordingly.
Point 2: The author asked to add fluid inclusions (FIs) instead of FIs only.
Response 2: I modified accordingly.
Point 3: What does "HT" stands for? Explain the abbreviation the first time it presented in the manuscript.
Response 3: This time the word HT (hydrothermal) is explained which put it Infront of it “…from the hydrothermal “HT” cements are recognized.”
Point 4: The ‘Introduction’ provides some context for the study but only within a restricted ‘local’ sense. It needs to present a rationale for this manuscript being published in an international journal – i.e., what are the implications beyond Harir-Spelek Basin?
Response 4: Kindly look again over the introduction, which there I had modified and add some other sentences, but in general the hydrothermal fluids in marine carbonate rocks is still in debate concerning their pulses, origin, especially the origin and timing, and this study together with previous one (Salih et al., 2019, 2020b) could solve a few problems in term of age and origin based on sophisticated techniques were used now and previously…
Really your feedback attracted my mind to put the introduction in a better shape…thanks again.
Point 5: The description of geological setting is not comprehensive.
Response 5: The text modified accordingly.
Point 6: Specify the heating and cooling rate. e.g. The heating rate was 1 °C/min from −40 to 30 °C. See Liu, Q., Sun, X., Li, D., Fu, Y., Zhai, W., Wei, H., ... & Zhang, X. (2019). The identification of the Guqiong orogenic Ag–Au polymetallic deposit in southern Tibet: evidences from mineralogy, geochronology and fluid evolution. Ore Geology Reviews, 111, 102950.
Response 6: Please look over the whole modified paragraph according to your feedbacks:
The occurrence of about 110 primary and secondary fluid inclusions are studied under the microscope. The temperatures are obtained by heating and cooling the inclusions in a chamber mounted on a microscope (Table 1). The fluid inclusions present contain two phases, i.e. a liquid (L) and a vapour phase (V). A minimum temperature of the fluid from which a specific mineral precipitated can be obtained during heating. The temperature at which the liquid and vapour phases homogenize is called the homogenization temperature (Th) and is the minimum temperature of entrapment of the fluid inclusion. Freezing and subsequent heating fluid inclusions allows to determine the temperature of first melting of aqueous solid phase and of the final melting. Based on these melting temperatures the major composition and of the salinity of the ambient fluid can be deduced respectively. The heating rate during homogenization of the fluid inclusions is 3°C/min and 1°C/min at the phase transitions during melting. The study and analyses have been performed at KU Leuven (Belgium). The preparation technique and measurement procedure have been described by Muchez et al. (1994).
Point 7: You need LABEL where your samples are collected from in the lithological column, figure (2).
Response 7: Thanks for your comment, because I had to cite this figure which published previously, and for label its hard to put the number of 200 samples because this is idealized litho-log from large area and the number of samples have been taken horizontally and vertically since we have a complex diagenesis due to hydrothermal fluids and the distribution body of hydrothermal fluids is different from crest or limb of anticline, beside the patch of different textural variation horizontally.
Point 8: Although the study recognized two types of fluid entrapment base on fluid inclusion petrography and microthermometry, the relationship between these fluid inclusions is less illustrated and their sequence is still dispute, thus the relationship between the formation fluid and studied fluid is unclear
Response 8: we re-write part of fluid entrapment in calcite and dolomite according to your comments, please look over the result part of calcite and the discussion part (2nd paragraph):
“The fluid inclusion petrography shows that most of the measured FIs in the saddle dolomites are aqueous fluid inclusions FIAs. The primary and secondary FIAs are the most dominant types, therefore the FIAs were entrapped during and after the crystal’s growth. Therefore, fluid inclusion petrography in saddle dolomites reveals two episodes of entrapments and thus more than one phase of HT fluid was channeled through the Bekhme carbonates. However, these two episodes were happened at two different times, but still the large secondary (mono-phase) fluid inclusions are trapped at the final stage of diagenesis, since the lack of vapour phase and characterized by large secondary FIs.”
Thanks again for fruitful comment.
Point 9: The picture seems blurry and I cannot see two phase of the FI (Figure 5).
Response 9: Kindly look over the new updated figure, I inserted a new figure also to be clear the fluid inclusion in closer scale.
Point 10: The font format in the pic seems strange (Figure 11).
Response 10: the font style and size are modified and homogenized …Please see the re-submitted file
Point 11: Use ABBREVIATION or FULL TITLE of the journals and make it consistent in all cited references.
Response 11: All the cited references have been checked and modified accordingly.
Point 12: I believe the title of this journal is Earth and Planetary Science Letters. Please check this problem.
Response 12: yes, the right journal name is Earth and Planetary Science Letters, it has been modified
Point 13: English language and style are fine/minor spell check required
Response 13: the whole manuscript has been edited again.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Authors,
I have read your interesting manuscript and find it a very well organized and well designed research output that fits well to the scope of the journal, Water. The manuscript combines many advanced techniques with good results that also provide interesting outcomes to consider in the general geology of the region. I think the manuscript technically ready for publication, however, to have it impactful some improvement is needed. I think the biggest shortfall of the manuscript is that the reader cant really get enough insight why this research is important and how its results fits or serve the big picture of the diagenesis and other major geological processes shaped your study area. I think some extra lines along this would be really good addition. Also, there are many minor issues that are individually not major, but all together just make the work fuzzy. I have marked those places ion the provided annotated PDF file. Also, the while the research is interesting and valid, the overall work is somehow floating e.g., disconnected. I think the discussion point a section would be really important to read how your results impact the general geological evolution picture of the study area, where and how this results could help us better understand the regional geotectonic and geoenvironmental evolution and how that influence the for instance the potential reservoir characteristics, etc.
I think a little bit more focused consideration of the above mentioned point would make the manuscript globally more relevant. I think a minor to moderate revision is needed.
Kind regard,
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 2 Comments
I would like to express my grateful to the 2st Reviewer for the valuable feedback in revising the manuscript, kindly below find the answer to all his/her comments and suggestions, major changes you will find it in the re-submitted file:
Point 1: (To gain insights on the origin and evolution of these diagenetic fluids, technique such as conventional petrography, cathodoluminescence, stable and radiogenic isotopes have been applied) do you mean in general or in your specific case?
Response 1: I meant here in general when we have a heterogeneity in carbonate rock, classical microscopes could not be enough to draw the complex sequential diagenesis of such rocks.
Point 2: cite your map figure here
Response 2: I cited map here (Figure 1)
Point 3: give an explanation sentence why? where are the issues and what cause them?
Response 3:
Previously and some recent studies interpreted HT as one phase based on general stratigraphy and structures of the studied area (Davies and Smith, 2006; Salih et al., 2019), while some recent estimated the absolute age of these fluids by utilizing laser ablation technique (U-Pb dating; Salih et al., 2020b)
Point 4: The Bekhme Formation is one of the carbonate reservoirs in the subsurface and is sometimes exposed to the surface. The question is oil or gas???
Response 4: The carbonate oil reservoirs, the question is answered accordingly and added in the text
Point 5: map resolution needs to be improved
Response 5: I inserted the map (Figure 1) in a high-resolution shape.
Point 6: add citation.
Response 6: The source is already inserted “During Permian, the opening of the Neotethys oceans started, and was associated with rifting along the ZFTB. The latter underwent complex tectonic events with extensional phases along both passive margins in the Late Triassic (Ismail et al., 2014)”
Point 7: while I think the figure is nice, it would be useful to see the real thing OR somehow link the fig 2 and 3 better
Response 7: Thanks for encouraging revision, but all these micro-digitized figures are taken from real one, and the reason why I could not link figure 2 and 3 because figure 2 is expressing the diagenetic event in different depth from that of figure 3.
Point 8: (Figure 5A and B) enlarge labeling as it cannot be read in the current style
Response 8: I modified the inserted text, also added another figure to be more clear (One=phase and two-phase of FIs )
Point 9: Add word condition: Petrographical observations indicate that saddle dolomites precipitated episodically during an early and late paragenetic sequence related to subaerial and submersion (Salih 315 et al., 2019).
Response 9: The modification is applied accordingly: Petrographical observations indicate that saddle dolomites precipitated episodically during an early and late paragenetic sequence related to subaerial condition and submersion (Salih 315 et al., 2019).
Point 10: The word extra-light means Low??: The cements filling open spaces were previously documented an extra-light value of δ18 O and δ13C and reported that the fluids involved in precipitation of these 361 cements is from hydrothermal fluids (Salih et al., 2019 & 2020b: see Figs. 10 & 11).
Response 10: Yes exactly, it does mean low oxygen isotope.
Point 11: English language and style are fine/minor spell check required
Response 11: the whole manuscript has been edited again.
Point 12: The final suggestions of the 1st Reviewer:
I have read your interesting manuscript and find it a very well organized and well-designed research output that fits well to the scope of the journal, Water. The manuscript combines many advanced techniques with good results that also provide interesting outcomes to consider in the general geology of the region. I think the manuscript technically ready for publication, however, to have it impactful some improvement is needed. I think the biggest shortfall of the manuscript is that the reader cant really get enough insight why this research is important and how its results fits or serve the big picture of the diagenesis and other major geological processes shaped your study area. I think some extra lines along this would be really good addition. Also, there are many minor issues that are individually not major, but all together just make the work fuzzy. I have marked those places ion the provided annotated PDF file. Also, the while the research is interesting and valid, the overall work is somehow floating e.g., disconnected. I think the discussion point a section would be really important to read how your results impact the general geological evolution picture of the study area, where and how this results could help us better understand the regional geotectonic and geo environmental evolution and how that influence the for instance the potential reservoir characteristics, etc.
I think a little bit more focused consideration of the above mentioned point would make the manuscript globally more relevant. I think a minor to moderate revision is needed.
Response 12: we modified the manuscript according to your comments and suggestions. Kindly look again to the re-submitted manuscript.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Dear Authors,
I have read your revised manuscript and find that you made all the requested corrections. I have no further request and recommend the manuscript to be accepted as it is.
Kind regards
