Geochemistry of Pyritic Mudstones from the Singa Formation, Malaysia: Insights into Gold Potential, Source of Sulfur and Organic Matter

Round 1

Reviewer 1 Report

Comments on the manuscript entitled “Geochemistry of pyritic mudstones from the Singa Formation, Malaysia: insights into gold potential, source of sulfur and organic matter” by Makoundi et al. submitted to “Geosciences”.

 

 

Global impression

 

As I said during my acceptation of review, I’m not a specialist of the sedimentary geochemical environment also I concentrate my review mostly on the organization part of the paper rather than on scientific consequences. Globally, this contribution appears as a good quality one, well presented and well written with enough illustrations. The quality of the data looks excellent such as the obtained results. Indeed my recommendation regards only minor revisions before publication and also a problem of internal organization that is consequent. See my main remarks below and others in the attached annotated pdf.

 

Regarding the manuscript organization, the main comments are:

• The presentation of the regional geology is a little too simplifies and needs, in my opinion, additional comments and information.
• In my opinion, the figures 1 and 2 can be re-organized as one. The figure 1 is not useful and can be erased or reduced as an insert.
• They are still some confusion with the geological map of the figure 1 in which some units are cited in the text and not in the figure. The map is too simplified to be informative. We don’t have idea of the general structuring, the geological relationship between different units, etc….Please improve this figure and the associated comments in the geological setting part.
• The part result is too short and need more information. I don’t understand why the results given by figure 10 or the Table 7 are presented during the discussion and not into the results part. I think that this point don’t help the reading and understanding of the paper. Although these figures effectively, these figures can represent data interpretation, I’m not sure that they are at the good place…Please, improve and strengthen the result part and reserve the discussion part to real discussion and not to data presentation.
• Finally, they are still a lack of clarified message given by your contribution that needs to be addressed in the introduction. The consequence on Au distribution? The source? Etc…
•  

Regarding the scientific part, and even if I’m not a specialist, my main comments are:

• I wonder if is possible to have black and reduced shale within a glacial-type deposit? Is this consistent? And moreover, the concept of glacial sediment origin is not addressed in the discussion and conclusion. Why?
• The classification in 6 pyrite types that are attributed to two families, primary and metamorphic/hydrothermal is not sufficient. This is not argued and presented in the chapter devoted to pyrite presentation (the too short section 5). Additionally, we discover with the table 5 and 6 that pyrites have attributed to a metamorphic/hydrothermal or a sedimentary origin but where is the discussion for that? Not satisfying!
• As an example, we discover in the discussion that the second pyrite type has lower Au value than the others….maybe the place for this is in the Result part….not during the conclusion. Idem for the d₃₄S values….This disturb me, just a little.
• I would prefer the part “result” developed, the part discussion better discussing the results and maybe, going further in the consequences of the result and that finally, the significance of your result will be better expressed and clarified because, at the end of the paper, the main and significant points of your paper are not sufficiently clarified, in my opinion.
• Part 1 of the discussion: for a no specialist, it remains difficult to follow what is common in most of the sedimentary rocks and what is the significance of your result? Maybe you can organize differently with an introduction with the common features and after, comparison with your results.
• Part 3: the discussion is not well-organized because you made a mix between the determination of the pyrite type and their potential enrichment….maybe you can separate the two problems…no? Except this, this part is fundamental and scientifically useful, even for an “unspecialist”.
• Part 4: idem…good discussion on d₃₄S distribution but sound more like results presentation than a real scientific discussion…

 

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Authors have taken into consideration all remarks and comments. All comments and responses are given below.

 

Comment 1 (Reviewer 1). The presentation of the regional geology is a little too simplifies and needs, in my opinion, additional comments and information.

Response 1. The regional geology has been revised in the manuscript (section 2). Section 1 has also been revised.

 

Comment 2 (Reviewer 1). In my opinion, the figures 1 and 2 can be re-organized as one. The figure 1 is not useful and can be erased or reduced as an insert.

Response 2. Figures 1 and 2 are combined and revised. It is now Figure 1A & B.

 

Comment 3 (Reviewer 1). They are still some confusions with the geological map of the figure 1 in which some units are cited in the text and not in the figure. The map is too simplified to be informative. We don’t have idea of the general structuring, the geological relationship between different units, etc….Please improve this figure and the associated comments in the geological setting part.

Response 3. The geological map which is provided in the revised manuscript (Fig. 1B) is now informative and contained all the units documented in the manuscript.

 

Comment 4 (Reviewer 1). The part result is too short and need more information. I don’t understand why the results given by figure 10 or the Table 7 are presented during the discussion and not into the results part. I think that this point don’t help the reading and understanding of the paper. Although these figures effectively, these figures can represent data interpretation, I’m not sure that they are at the good place…Please, improve and strengthen the result part and reserve the discussion part to real discussion and not to data presentation.

Response 4. Table 7 was moved to result section and re-numbered as numbered as Table 4.

 

Comment 5 (Reviewer 1). Finally, they are still a lack of clarified message given by your contribution that needs to be addressed in the introduction. The consequence on Au distribution? The source?

Response 5.  The introduction section has been revised according to the reviewer’s comments.

 

Comment 6 (Reviewer 1). Regarding the scientific part, and even if I’m not a specialist, my main comments are:

I wonder if is possible to have black and reduced shale within a glacial-type deposit? Is this consistent? And moreover, the concept of glacial sediment origin is not addressed in the discussion and conclusion. Why?

Response 6. The dark or black mudstones of Singa Formation have shown a suboxic-oxic conditions and not anoxic or euxinic conditions. So, it is expected to see such redox conditions in glacial deposits.

 

Comment 7 (Reviewer 1). The classification in 6 pyrite types that are attributed to two families, primary and metamorphic/hydrothermal is not sufficient. This is not argued and presented in the chapter devoted to pyrite presentation (the too short section 5). Additionally, we discover with the table 5 and 6 that pyrites have attributed to a metamorphic/hydrothermal or a sedimentary origin but where is the discussion for that? Not satisfying!

Response 7. The origin of the pyrite has been clarified in the manuscript. Results in Tables 5 and 6 were discussed.

 

Comment 8 (Reviewer 1). As an example, we discover in the discussion that the second pyrite type has lower Au value than the others….maybe the place for this is in the Result part….not during the conclusion. Idem for the d34S values….This disturb me, just a little. I would prefer the part “result” developed, the part discussion better discussing the results and maybe, going further in the consequences of the result and that finally, the significance of your result will be better expressed and clarified because, at the end of the paper, the main and significant points of your paper are not sufficiently clarified, in my opinion.

Response 8. Conclusion has been revised. Any data reflecting results have been deleted.

 

Comment 9 (Reviewer 1). Part 1 of the discussion: for a no specialist, it remains difficult to follow what is common in most of the sedimentary rocks and what is the significance of your result? Maybe you can organize differently with an introduction with the common features and after, comparison with your results. Part 3: the discussion is not well-organized because you made a mix between the determination of the pyrite type and their potential enrichment….maybe you can separate the two problems…no? Except this, this part is fundamental and scientifically useful, even for an “unspecialist”. Part 4: idem…good discussion on d34S distribution but sound more like results presentation than a real scientific discussion.

Response 9. In the Discussion part, there is a new paragraph on “trace element deportment” to discuss  enrichment or depletion for some trace elements in pyrite.

 

A copy of the manuscript with all the revised sections is attached

 

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

I revised the manuscript “Geochemistry of pyritic mudstones from the Singa Formation, Malaysia: insights into gold potential, source of sulfur and organic matter” and in my point of view this research is conducted well, laying the groundwork for the development of novel studies reporting the metal content of black mudstones in the Singa Formation, evaluated from both pyrite trace element chemistry and whole-rock analyses.  It could be important for increasing actual studies on this topic in general. 
The employed techniques are adequate for the study and the quality of the results is good.
However, some corrections and revisions should be made. Please follow the list below:
- Figure 1: please check the quality, if possible, please use better resolution.
- Line 89: please check the verb “indicates” seems to be repeated 2 times.
- Lines 239-241: the percentages indicated in the brackets are referred to what? Are the medium values of each major oxides? Please specify better this point.
- Table 7: please homogenize this table to the others presented in the paper.

Regards

Author Response

Dear reviewer,

Authors have taken into consideration all remarks and comments. All comments and responses are given below.

Comment 1 (Reviewer 2)

- Figure 1: please check the quality, if possible, please use better resolution.

- Line 89: please check the verb “indicates” seems to be repeated 2 times.

- Lines 239-241: the percentages indicated in the brackets are referred to what? Are the medium values of each major oxides? Please specify better this point.

- Table 7: please homogenize this table to the others presented in the paper.

 

Response 1 (Reviewer 2). All comments have been addressed. Figure 1 was deleted and replaced by another figure which is more informative. Lines 239-241: the percentages are referred to mean values. Table 7 was moved to result section and adjusted accordingly.

Author Response File: Author Response.docx