Geochemistry of Sphalerite from the Permian Volcanic-Hosted Massive Sulphide (VHMS) Deposits in the Tasik Chini Area, Peninsular Malaysia: Constraints for Ore Genesis

Round 1

Reviewer 1 Report

The manuscript by Basori et al. “Geochemistry of Sphalerite from the Permian Volcanic-hosted Massive Sulphide (VHMS) Deposits in the Tasik Chini Area, Peninsular Malaysia: Constraints for Ore Genesis” aims to make a contribution to the formation of Bukit Botol and Bukit Ketaya ore deposits through the petrographic and geochemical (EPM data) investigation of sphalerite. It means that the theme “ore-forming conditions for VHMS deposits” is of broad interest for an international readership. Nevertheless, the manuscript makes little contribution on this topic and it needs to be improved.

In my opinion, the petrographic investigation is the main problem of the manuscript because it is not adequate to support the conclusions. I think it is crucial to improve the textural description of the sphalerite ore and whether the sphalerite has, or has not, undergone post-formation changes (e.g., recrystallization). The recrystallization of sphalerite is a common process in deformed and metamorphosed rocks (see e.g., Lockington et al., Miner Petrol 2014 and reference therein) and the Bukit Botol and Bukit Ketaya deposits have experience deformation and metamorphism. In the lines 169-173, the authors describe chalcopyrite inclusions in sphalerite (“chalcopyrite disease”) but it is unclear the origin. In the lines 264-277, the authors discuss the sphalerite chemical data using the Fe content as indicator of the physico-chemical conditions of formation. If the “chalcopyrite disease” is not a primary feature then the Fe content is not representative of the formation conditions. Furthermore, in the lines 278-291, the authors attribute the high-Cu content in the EPM analysis at chalcopyrite micro- to nano- inclusions but the same analyses have also the higher Fe contents. Thus, the authors should discuss the origin of the sphalerite textures and whether or not the analyses represent mixing of two or more phases.

The Tables 1-4 should be improved. The tables report average calculation of different spot analyses but the methods for the calculation are not described in the manuscript. I suggest to add it in the “Analytical Methods”. Furthermore, the Zn/Mn ratios are largely wrong because the authors attribute the value of “0” when the Mn is lower than the detection limit. Thus, the authors can modify the tables (also the Table 5) and the manuscript with a correct mathematical treatment. Furthermore, I think it is useful to insert all the spot analyses in a Supplementary Materials table.

The conclusions do not make substantial contributions to the formation of VHMS deposits nor for the Bukit Botol and Bukit Ketaya deposits. In fact, the conclusions are substantially the same as those already published by the same authors (Basori et al., International Geology Review 2016; Basori et al., Island Arc 2016; Basori et al., Turkish Journal of Earth Sciences 2017; Basori et al., Journal of Asian Earth Sciences 2018; Basori et al. Ore Geology Reviews 2019; Basori et al. Journal of Asian Earth Sciences 2020).

In this regard, I point out that the figures 1, 2, 3 and 4b,c are the same as those already published. It is therefore necessary to modify them.

Finally, I added my corrections, comments, and suggestions in the annotated text.

I suggest that the manuscript should not be published in the actual form.

Comments for author File: Comments.pdf

Author Response

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Reviewer 2 Report

This manuscript:

• has high scientific soundness.
• has well written introduction.
• has welll and analytically  given geological description of the study area with really useful map and cross sections of both deposits.
• contains modern analytical methods which have been well described.
• has well given results which also contain useful and clear images and plots.
• Tables 1-4 could be a supplementary file.
• contains a really well written and established discussion.
• haw really clear and compact conclusions which give answers to the initial research objectives.

For all the above reasonsi suggest this paper to be published in the present form.

Author Response

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Reviewer 3 Report

Interesting paper and a worthy contribution. I have provided annotated manuscript with corrections.

A few key points:

We Need to know the general metamorphic grade, I suspect lower to middle greenschist, it needs t be explicitly stated, as this can affect Sp-chemistry during P-T re-equilibration.

Figures 2 and 3 cross sections need revisions - Are these based on DDH traces? If not, then the authors should take more artistic license to sketch VMS mineralization that is more realistic to that observed in VMS exposures worldwide. Is there a geological plan map of the region from which the sections are taken?  Figure captions do not provide any context and need to be expanded.

Perhaps a Strat column with the relative position of the samples analysed might be of use, specifically when discussing trends in Sphalerite chemistry proximal-distal.

I recommend producing box an whisker plots of your data. Would greatly improve the data presentation.

The interpretation of trace Ag contents in Sphalerite is probably correct, but the LA-ICPMS data would provide better evidence. I would be cautious in interpreting too much from trace Ag by EPMA.

The 2nd last paragraph in the discussion describing the effects of footwall felsic volcanics on Zn/Cd ratios in sphalerite should be removed. Not enough supporting evidence, and difficult to argue. 

Comments for author File: Comments.pdf

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Reviewer 4 Report

Overview

The ms by Basori et al. entitled: “Geochemistry of Sphalerite from the Permian Volcanic-hosted

Massive Sulphide (VHMS) Deposits in the Tasik Chini Area, Peninsular Malaysia: Constraints for Ore Genesis” presents data from sphalerite chemistry from the two Bukit Botol and Bukit Ketaya deposits (Tasik Chini Area, Peninsular Malaysia). Data presented of sphalerite were obtained at the Central Science Laboratory (CSL), University of Tasmania using a Cameca SX50 electron microprobe (EPMA).

It is demonstrated in the paper that the compositional variation in sphalerites reflects variable temperature and activity of sulphur in the hydrothermal fluids during ore formation and related to contrasting depositional processes.

The ms is well-written, and the general plan is suitable. The figures are all necessary and of good quality except one (see below). The reference list is complete and up-to-date.

Data presented by Basori and co-authors reach a high scientific level and therefore can be accepted in an international journal as Minerals after some very minor revision.

Three details :

• figure 2 is very schematic and looks like a drawing of a first year university student. It must therefore be improved.
• Figure 4 (photomicrographs) is not of very good quality (predominantly blue) either but this may be due to editing and printing.
• Figure 4 (and elsewhere): please use international abbreviations for minerals as recommended for example by Withney and Evans (2010), American Mineralogist. galena: Gn; sphalerite: Sp….

Author Response

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Round 2

Reviewer 1 Report

Dear Authors,

the manuscript has been improved. However, I believe that some points have not been fully resolved. In particular, the petrographic investigation does not clarify whether ore textures are primary or due to metamorphic processes.

Additional comments:

The figures have been improved. However, I still don't understand the cross-section in Figure 1a. What does the orebody above the open pit pond represent? Is it an already exploited ore volume? If yes, you have to indicate it in the figure (e.g., using brighter colors). In the actual state, the cross-section is difficult to understand.

The Tables 1-4 must be improved because there are still many errors. In some cases, the e.g., Zn/Mn ratio = 0 when the Mn

than 948 (the lowest value for Massive Sulphide of Bukit Botol). The same considerations are valid for all the other tables and mean values and should be accordingly changed in the manuscript.

I added some corrections in the annotated text.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf