Review Reports - The Ophiolite-Hosted Cu-Zn VMS Deposits of Tuscany (Italy)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

Your paper is an interesting and really valuable review as well as basic documentation (with a quite modern approach) of the VMS deposits in Tuscany, therefore it is definitely worth of publishing in Minerals. However, in its present form it is too long and some parts are really hard to follow due to long and difficult paragraphs. Therefore, I have several suggestions below, including preparation of some sketch drawings to assist the readers, which I hope, help You to improve Your manuscript.

Introduction

-line 38: only in the 19th century?

-line 48: maybe a few additional references to prove the scientific interest would be good here

-line 55: the reason of what? not clear

-line 55-60: I do not understand, how this paragraph is linked to the other parts of the text?

Geological background

-line 106: not only sedimentary successions, as You also state, large ophiolitic blocks are found there...

-fig2: what do T1,2,3 mean? and also, legend for B figure is missing

-lines 151, 154, 156 and throughout the text: pillow basalt (it is not lava anymore)

-the whole chapter could be a bit more concise

The Tuscan Cu-Fe-Zn VMS deposits

-do we know anything about the exact deposit type? how did early authors prove the VMS origin, if seemingly no massive ore is found here? please, clarify this question here.

-lines 248-250: this is not enough about the study methods. Please, instead, include a separate (sub)chapter for the methods, where You can describe clearly and detailed the used equipment.

T1 type ore

-somehow You should be more concise, as the text is definitely too long. Pay attention not to mention anything rwo times (e.g. several information is occuring already in the introductionary part, than re-appear in the detailed ore body geometry... subchapter)

-line 354: how can You reliably distinguish between covellite, digenite and djulerite with the mentioned methods?

-a sketch to show the veins structure and the results of revorking processes and/or a generalised mineral precipitation series based on the textural observations would be highly appreciated, as they would definitely help the understanding of this complex mineralisation. In that way, readers could much better follow Your description.

T2 type ore

-somehow You should be more concise, as the text is definitely too long. Pay attention not to mention anything two times

-please, be consistent with the names (adit/tunnel/stope)

-line 451: You did not mention the use of EPMA before. Please, include in the methods. And also, You could include the measurement result in the form of an appendix table

-a sketch to show the veins structure and the results of revorking processes and/or a generalised mineral precipitation series based on the textural observations would be highly appreciated

T3 type ore

-line 457: why are you talking here about T1 type, this chapter should be about T3 type?

-lines 458-471: most of the information here already appears in the text. Please, eliminate any duplicates, as the text is really too long.

-fig 10: legend is not containing the red lines for cross sections

-it is very hard to follow the description in 3.3.1, please, try to help the reader e.g. with a sketch draw of the deposit structure

-fig 13: show with rectangle on fig A, where is the position of fig B

-a generalised mineral precipitation series based on the textural observations would be highly appreciated

Discussion

-line 683: please, discuss, how they are compatible with the proposed model? (they look so "atypical", therefore I think this topic deservs some explanation)

-line 689: how can you prove, that T2 is the reworked analogue of T1 ore type? please, discuss.

-lines 694 vs. 684: then are they subseafloor or seafloor deposits? please, be consistent!

-line 723: that sounds logic, but then what could be the cause of this reworking?

-can You still refer to the "reworked" T2 and T3 deposit types as VMS?

-lines 775-780: and what about the quite simiar magmatic textures? please, discuss, how can You exclude that option (as the host is mafic-ultramafic intrusive rock...)?

-CRM potential: what if the fluid source have an effect on this? do You ave any proofs for magmatic fluid input? if not, how would You study in the future?

-line 864: is it sure, that every VMS system has such deep traceable feeder zone? maybe this is a bit too much generalised.

-line 874-880: I cannot really understand this idea, could You please clarify?

Conclusions

-a remark on the CRM potential would be good here, as its evaluation was also included in the aims of the study

Comments on the Quality of English Language

Minor editing is required.

Author Response

Dear Reviewer,

thanks a lot for your comments.

We tried to answer all the questions. Thanks to your comments we significantly implemented the manuscript rephrasing some parts, drawing a final cartoon and providing as supplementary materials a geochemical table and a Method chapter.

here our answers point by point:

Line 38 – Yes, production of copper from Tuscan ophiolite-hosted VMS was important in the XIX century only. During the XX century some exploration was performed but real production was not provided.

Line 48 – It’s hard to find a single comprehensive reference. We should introduce several REFs for international workshops, congress field trips, etc. The manuscript is already long, and we did not introduce new REFs.

Line 55 – corrected: “… The reason for such a scientific popularity is the great … “

Line 55-60 – This paragraph explains why, although the economic interest is declined, the Tuscan magmatic-hydrothermal systems are still actively studied by scientists.

Line 106 – corrected: it was specified that sedimentary formation “ … deposited on the Jurassic basalt-gabbro-serpentinite oceanic crust.” The Internal Ligurian Units have an ophiolitic basement. Ophiolite olistoliths are embedded in External Ligurian Units.

Fig. 2 – The caption was integrated and corrected.

Line 151, 154, 156 and rest of text: – corrected: OK Pillow basalt

The Cu-Zn deposits described in this manuscript are poorly characterized. The VMS affinity has been proposed in the past (see REF N° 1 and references therein) being hosted in ophiolites. A detailed description is provided in the next chapters.

Line 248-250 – Methods are now included in a Supplementary file.

Line 354 – corrected: We cancel the names of the minerals (identified by Italian mineralogists by single-crystal XRD; personal communication, unpublished data) leaving a generic “Cu sulfides”.

Line 451 – corrected: We prepared a supplementary file for all the methodologies.

Line 457 – corrected: “T1” in paragraph 3.3 was a refuse. Corrected with “T3”.

Figure 10 – In Figure 10 of the submitted version of the manuscript, cross section traces are highlighted by red lines. Reviewer 1 maybe had problems with software visualization.

Figure 13 – Fig. 13B is an enlargement of the central vertical zone of Fig. 10A. It is detectable looking at the textures/colors of the images.

Line 683 – the Tuscan VMS are discussed throughout all the chapters of the Discussion.

Line 689 – T2 ore derives from reworking of T1 type as described in chapter 3.2.1, Lines 409-412)

Line 694 vs. 684– corrected. Line 684 and 694 have been rephrased. All the Tuscan VMS deposits show geological characters of sub-seafloor deposits. The VMS deposits of Liguria display the whole range of depositional setting from seafloor to sub-seafloor.

Line 723 – the tectonic displacement shown in cross section of Figure 10 (discussed by lines 721-734) was controlled by the Apennine Miocene extensional tectonics, as described in the paragraph between line 735 and 738. Despite the significant deformation, hydrothermal effects (chemical re-mobilization of orebodies) were negligible during this stage.

Line 775-780 – Our investigation of these textures is ongoing. We introduced them here to show the textural complexity of the T2 and T3 ore types. We interpret this reaction as a hydrothermal reworking of the “normal” primary ore occurred during the oceanic evolution of these ore systems. The main constraint is the co-precipitation of bornite (and other accessories like clausthalite, hessite, native tellurium) with hydrothermal alteration minerals like quartz, chlorite, Ca-amphibole, andradite, etc (see chapters 3.2.2, 3.3.2). Obviously, additional work is ongoing (bulk and in situ geochemistry; isotope analyses) and we will try to better constrain the origin of these complex VMSs in future papers.

CRM Potential – We described the abundance of accessories (clausthalite, telluriun, hessite, gold-electrum) to stress the Se, Te, Au and Ag rich character of these ores. The discussion was introduced to stimulate further investigation on VMSs from Liguria and Tuscany that could be useful for the global debate on geochemistry of VMSs and SMSs. The research is ongoing, and it will be the subject of future papers.

Line 864 – OK, the sentence was not clear enough. We followed the suggestion, and we removed it.

Line 874-880 – the sequential history described in lines 874-882 is provided by the intersection relationships (field and petrographic data provided in previous chapters) between dunite channels and harzburgite, their later hydration to serpentinite and intrusion by plutonic gabbro bodies, and finally by the intrusion of subvolcanic dolerite dykes and deposition of pillow basalts, with hydrothermal sulfide assemblage overprinting everything.

All the best

Andrea Dini and co-authors

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

I have now read the manuscript of a review article-type submitted by Dini et al. (2023) entitled "The ophiolite-hosted Cu-Fe-Zn deposits of Tuscany (Italy)". I recommend that the article be awarded subject to a minor-moderate revision. Basically, I found that the manuscript is well written supported by deep literature review, which supported by some mineralogical and geochemical data. The manuscript, however, needs to be upgraded in some points as suggested, before to be recommended for publication. More details of suggested corrections are available as follows and in the annotated file attached.

1). Line 251- T1 ore type, stockwork should consist of several vein/veinlet types. It is suggested to describe more details the types of veins/veinlets sequentially according to their cross-cutting relationship and distinctive characteristics (ore mineral assemblages, alteration mineral selvages, textures, pattern, etc).

2). Line 255-Fig.5B,D,F,H may need graphical scale.

3). Fig.7, 9 - convert the complete mineral names into standard mineral abbreviations, and put the abbreviations at the end of the figure captions.

4) Line 809-etc (Sub-Chapter Geochemical Signatures...): It is suggested to incorporate the summary/representatives of ore chemical data from the three Tuscan ore types (T1, T2 and T3). The complete data might be put as Supplementary Tables.

5). Line 854-etc: As outlined in the Introduction section of this manuscript, one of the background spirits of this work is to identify the potential energy-critical metals/elements possibly hosted by the Tuscan ophiolitic-VMS deposits. I think the manuscript needs to discuss that topic deeper and more details to give more added values of the manuscript.

6). It might be suggested to add Sub-Chapter 4.5 Genetic Model of the Tuscan VMS deposits, to develop a generalized 2D or 3D genetic model of the deposit and to discuss the interrelation of genetic characteristics of the deposit. Thank you!

Sincerely,

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

thanks a lot for your comments.

here our answers point by point:

1) Line 251 – The textural and mineralogical details, as well as cross cutting relationships between hydrothermal stockworks/dissemination and host rocks are described in chapter 3.1.1 and 3.1.2.

2) Line 255 Fig 5 – Ok. Graphical scale has been added.

3) Fig 7-9 – all the Figures (7 to 15) have been corrected.

4) Line 809 – Supplementary table has been added.

5) Line 854 – few sentences on energy critical metals have been added.

6) Discussion Conclusion – a 2D graphical model with a preliminary hypothesis of ore evolution has been provided. However, the ongoing investigation (bulk and in situ geochemistry, isotopes) must be completed before to develop a robust interpretive model.

all the best

Andrea Dini and co-authors

Reviewer 3 Report

Comments and Suggestions for Authors

Review of manuscript minerals-2727072

Andrea Dini, Andrea Rielli , Paolo Di Giuseppe , Giovanni Ruggieri , Chiara Boschi “The ophiolite-hosted Cu-Fe-Zn deposits of Tuscany (Italy)”

This is an excellent overview of some of the VMS deposits in Tuscany. These deposits are currently not exploited and some are geoparks.

It seems to me that the work needs to be structured a little more strictly, with a separate historical overview and not mixing the results of the work and the discussion. Thus, paragraphs 208-217, where the ores of Tuscany and Liguria are compared, are clearly more relevant to the discussion; paragraph 218-227 is a historical excursion. There are several more similar remarks (293-296, for example).

It is not very clear how specific zonal bornite-chalcopyrite aggregates are formed. The situation, in general, resembles a zone of secondary copper enrichment of sulfide ores, including in near-bottom conditions. What model do the authors adhere to?

In discussing geochemical features, comparison with data from modern hydrothermal edifices seems controversial. First of all, there is a difference in testing methods. In addition, it is clear that modern sediments will differ from the ores of ancient hydrothermal systems. It's better to take them for comparison. For example, there are works by I. Melekestseva on the Ishkininskoye field.

Perhaps these links will be useful

Durazzo A., Taylor L.A. Experimental exsolution textures in the system bornite-chalcopyrite: Genetic implications concerning natural ores // Mineralium Deposita 17(1). 1982. 79-97

Some misprints?

Line 84 woks – works

What is mean prefix “pluri”?

Hope, it will be useful.

Author Response

Dear Reviewer,

thanks a lot for your comments.

here our answers point by point:

The main comment of Reviewer 3 is about the genesis of the bornite-rich assemblage (type 2 and 3) replacing the original chalcopyrite assemblage. We interpret this reaction as a hydrothermal reworking of the “normal” primary ore occurred during the oceanic evolution of these ore systems. The main constraint is the co-precipitation of bornite (and other accessories like clausthalite, hessite, native tellurium) with hydrothermal alteration minerals like quartz, chlorite, Ca-amphibole, andradite, etc (see chapters 3.2.2, 3.3.2). Obviously, additional work is ongoing (bulk and in situ geochemistry; isotope analyses) and we will try to better constrain the origin of these complex VMSs in future papers.

Moreover, Reviewer 3 suggest making a discussion comparing geochemical features of Tuscan VMss with present day oceanic systems. This is a cool suggestion, but our Review is already quite long and full of geological, mineralogical, geochemical information. We decided to postpone this discussion in future contributions.

all the best

Andrea Dini and co-authors

Reviewer 4 Report

Comments and Suggestions for Authors

Review of the manuscript „The ophiolite-hosted Cu-Fe-Zn deposits of Tuscany”

This study reviews the Cu-Fe-Zn deposits of Tuscany which are classified as ultramafic/mafic hosted VMS deposits. To do so the authors use detailed field mapping and ore petrography. The mineralizations in Tuscany are subdivided in 3 types: 1) stockwork and disseminated, 2) brecciated in ultramafic rocks and 3) brecciated at the contact between ultramafic and volcanic rocks. This study provides new insights and understandings about the still poorly characterized ultramafic-hosted VMS deposits (UM-VMS).

The manuscript, nevertheless, could be improved on several aspects. First, although well written the style of the manuscript can be improve, it reads in places as a report. This is particularly the case in the introduction where it is mostly about the mining history of the area. The introduction should be rewritten and the main problematic of the manuscript should be highlighted. An easy problematic which the manuscript clearly addresses is if the investigated minerlizations can be classified as UM-VMS or not, and how they fit/improve the models.
Additionally, in the manuscript it is stated that XRD and EMPA data have been done, however there are no method and result sections describing such data. As these data are not core to the manuscript they could be added as supplementary data. Finally, the section 4.4 of the discussion should be reworked as it is sometime a bit speculative.

This study is really interesting but it needs to be improved before publication. Hence, I recommend major revisions. Please find my detailed comments below.

Clifford Patten

Detailed comments:

Line 1: Perhaps change title and integrate “volcanogenic massive sulfide deposit”. Also Fe is not of interest for this type of deposits, perhaps switch to “high Cu-grade”.

Line 21: Are the authors sure it was a spreading ridge or an ocean-continent transition?

Line 27 to 75: Most of the introduction is too focused on historical mining activities and should be rewritten around the main scientific problematic of the manuscript.

Line 76 to 91: Although the aims of the manuscript are clear, the problematic is not. I do not think that before the work presented in this manuscript it was well established that the Cu-Zn-Fe mineralizations of Tuscany were actually UM-VMS deposits (for instance I did not know about these deposits). A possible and clear problematic would be to re-evaluated if the investigated mineralizations are actually UM-VMS deposits (which clearly seem to be based on the work of the authors) and how it improves our understanding of such systems, as stated line 88-89.

Line 84: remove “priceless”

Line 91: Not clear what orogenic and oceanic settings refer to.

Line 137: Fig. 2A is nice but it is a model which seems out of place in the section “geological background”. This model is the outcome of the petrographic and mapping work of the study and should be in the discussion. This model highlights that the studied mineralizations are sub-seafloor UM-VMS, which in my opinion is the main outcome of the study. Also T1-2-3 in fig. 2A are not in the caption.

Line 155: “Micro-gabbro” instead of “porphyritic dolerites”?

Line 169-170: Too long and confusing sentence

Line 179: “Low angle detachment fault” rather than oceanic core complex. OCC are usually used only for pure MOR setting, not so much for OCT.

Line 182: A method section for the XRD and EMPA analysis is missing (as well as a result section). As these analyses are not core to the manuscript perhaps they could be added as supplementary information.

Line 184: “This review focuses…”

Line 200: “then“ instead of “than”

Line 208 to 216: The differences with the Ligurian VMS deposits are interesting and highlight the need to re-evaluate the deposits of Tuscany as UM-VMS deposits and how they help to better understand their genetic model.

Line 218 to227: This paragraph in not necessary.

Fig. 4: Perhaps use % instead of µg/g. I would make the fig. way easier to read.

Line 293-296: Not necessary.

Line 331: Fig. 7, state these are SEM pictures.

Line 360-386: Any estimation of the temperature range based on mineralogical assemblage?

Line 370: Rephrase “Even this type…”

Line 395-397: Cannot see on Fig. 8.

Line 420:”…prevented the full development of this deposit”, this statement is too speculative.

Line 451: Which EMPA analysis? Should be stated in method and result sections.

Line 458-466: Some repetition and not needed.

Line 529: Use present tense perhaps.

Line 606: Missing “.”

Line 674-680: This paragraph should be in the introduction, not in the discussion.

Line 685: Along a spreading ridge or an ocean-continent transition?

Line 693-698: Yes but the Reppia and Bardenento deposits from the Liguria for example are at the contact between ultramafic and volcanic rocks similar to the T3 MVC deposit.

Line 699: Do the authors mean “ore deposition on the seafloor” in opposition to sub-seafloor? It is not clear.

Line 729-730: Please rephrase.

Line 781-789: The chalcopyrite-bornite reactions are different between [58] and [61]. In [58] the reaction is due to Cu input in the system while in [61] it is due to Fe removal under oxidizing conditions. It has some importance on the genetic processes, please clarify.

Line 799-801: Perhaps replace “critical and precious metals” by trace elements/metals. All the elements in these minerals are not critical/precious.

Line 809-850: The parameters controlling Co/Ni in VMS deposits is actually not clear and it is also not clear what information the Co/Ni of the Tuscan VMS deposits provide. Perhaps clarify or remove from discussion.

Line 851: Starting the paragraph with a question is a bit odd. Please rephrase.

Line 864: remove “us”.

Line 871: Please rephrase, “they have been lost” instead of “we have lost them”.

Line874-881: Not very clear, please rephrase.

Line 887-893: This is possible but it is quite speculative. For instance, serpentinization is occurring up to ~400 °C while magmatic emplacement at plutonic levels likely occurred at higher temperature and earlier…

Line 894: Rephrase the beginning of the sentence.

Line 908-912: These mineralogical assemblages form at high temperatures (see work by Colat for example) and possibly does not fit with a late-stage hydrothermal circulation. Please clarify.

Line 914: Master?

Line 941: The 3D reconstruction?

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The quality of the English is good.

Author Response

Dear Dr. Patten,

thanks a lot for your comments.

here our answers point by point:

The comments by Dr. Patten are welcome and we tried to answer to our best. This manuscript has been thought as a review paper on ore deposits that are poorly known by both international and Italian scientific community. Considering the new interest for Critical Raw Materials (see the recently approved Critical Raw Materials Act by European Parliament), the main goal was to provide a modern discussion of the Tuscan VMS deposits to trigger more scientific investigation by other scientific groups (structural geologists, petrologists, mineralogists), as well as to create interest for industrial companies that are currently involved in mineral exploration in Italy. These companies are formally exploring for Cu but they could consider also the potential for critical metals like Se, Te and Co.

We know that the manuscript is quite long in several sections, but we believe that the details about the mining history and parks activity is important to contextualize the subject and to provide useful information for future scientific and exploration activity in Tuscany.

Line 1 – Ok, suggestions have been considered.

Line 21 – We believe that the Tuscan VMS/ophiolite system (and the nearby system in Liguria) represents a remnant of a slow spreading ridge in which the new oceanic lithospheric mantle was not yet involved or partially involved (or not yet discovered! - most ultramafic outcrops are pervasively serpentinized and the petrological studies available in literature were focused on few well-preserved outcrops), but where the tectono-magmatic-hydrothermal activity had already reached a mature stage. To produce ore deposits, a robust and long-lived magmatic system is needed. The Tuscan VMS-ophiolite system possibly formed at the inception (?) of a slow spreading ridge at the Ocean-Continent transition of the Ligurian-Piedmont ocean.

OCT is a nice and intriguing geological setting but being either submerged along passive oceanic margins or disrupted along orogenic belts, its nature is still poorly defined. The extent of the magmatism and the metallogenic potential of the OCT regions have yet to be evaluated, and we do not have the reliance to solve this question through a review paper of such poorly studied deposits and, moreover, hosted in such a complex tectonic context. The available data are compatible with a hydrothermal system that developed along a slow spreading ridge. Future work will perhaps allow us to understand the rest.

Moreover, several present-day OCT along oceanic passive margins seems to involve significant amount of continental crust. Tectonic slices of continental crust have never been described from the sequences of Internal Ligurian Units. The occurrence of continental crust in the original crustal section during the development of the VMS hydrothermal systems, would have provided highly radiogenic Pb. However, the available lead isotope data on Tuscan VMS and Ligurian VMS are consistent with a MORB-like Pb isotope signature. (e.g. Chiarantini et al., 2018. https://doi.org/10.1016/j.jasrep.2018.02.005; Nimis et al., 2020 https://doi.org/10.1127/ejm/2018/0030-2696). We produced very detailed isotopic and trace element data of Tuscan VMS that will be the core of future publications.

Line 27-75 – This comment has been already answered before.

Line 76-91 – Ok, suggestions have been considered.

Line 84 – Ok, “priceless” was removed.

Line 91 – Ok, the end of the sentence was modified: “ … but for possibly recovering energy-critical metals like Co, Ni, Te and Se from mafic/ultramafic-hosted deposits in orogenic and oceanic settings.

Line 137 – The caption of Figure 2 has been modified referring to the text. Figure 2 anticipates the text description (ore types), but it was done to minimize the number of the Figures. We would like to leave figure 2 in the introductory part but, following your suggestion (and othere reviewers), we made a new figure at the end to illustrate the sub-seafloor model.

Line 155 – The dolerite dykes are real sub-volcanic porphyritic bodies with phenocrysts of plagioclase set in a very fine-grained to cryptocrystalline groundmass. It is possible to use both volcanic/plutonic terms for this rock types, but we preferred the largely used term “dolerite” to distinguish them from real equigranular microgabbros that are associated, in the study area, with the earlier gabbro plutonic complex (gabbro, pegmatoid gabbro, microgabbro and flaser gabbro).

Line 169-170 – OK; the sentence was fixed (it was truncated and partially duplicated by mistake).

Line 179 – We would like to maintain “OCC tectonics”. See the explanation in the introduction of this reply about the Ligurian ocean and its heterogeneous nature (from subcontinental to oceanic mantle; Rampone and Sanfilippo, 2021).

Line 182 – OK; We prepared a supplementary file for all the methodologies. We eliminated EPMA (not really used in this contribution). A table with geochemical data used for figure 4 and 16 has been also added as Supplementary material.

Line 184 – Ok, fixed.

Line 200 – Ok, fixed.

Line 208-216 – Yes, the re-evaluation of Tuscan VMSs is addressed in the Discussion Chapter.

Figure 4 – Ok, fixed (Fe %).

Line 218-227 – We would like to maintain this paragraph to stress the relevance of old mineral collections, papers, reports as well as the great opportunity to access abandoned underground works provided by mining parks.

Line 293-296 – description of local architecture of host rocks is relevant to understand the extreme tectonic segmentation experienced by the ophiolite + VMS complex.

Line 331– Ok, fixed.

Line 360-386 – We did some EPMA on chlorite and other silicates, but the investigation is ongoing. We didn’t want to interpret a preliminary and partial dataset.

Line 370 – Ok, fixed.

Line 395-397 – Yes, in figure 8 sedimentary covers are visible in the NE corner. This contact continues northward, and basalt appears. We left this outcrop outside the figure to minimize the size.

Line 420 – the sentence was not clear, and it was modified: “The irregular, anastomosed nature of the cataclastic zone and the sudden closure along strike/dip of the ore shoots prevented the industrial progress of this deposit.”

Line 451 – Ok, EPMA has been canceled; these analyses are not used in the manuscript.

Line 458-466 – This part is important to introduce early authors and make clear the difficulty to study abandoned deposits through documents, old museum samples and underground exploration.

Line 606 – Ok, fixed.

Line 674-680 – the paragraph was totally re-written.

Line 685 – Ok, fixed. “… the slow spreading ridge”.

Line 693-698 – Yes, some VMS in Liguria have the same stratigraphic position of Tuscan VMS. However, they usually have a “normal” Py-Cpy-……. mineralogical assemblage. A sentence about the occurrence of subseafloor deposits in Liguria has been added in the next paragraphs.

Line 699 – Ok, fixed.

Line 729-730 – Ok, fixed. The sentence has been deleted.

Line 781-789 – Ok, we changed a bit the sentences. In this moment it’s hard to say which process (Fe removal vs. Cu input or a coupled mechanism) was active. We hope that the ongoing investigation, involving both the sulfides and the co-genetic gangue silicates will shed new lights on these odd textures.

Line 799-801 – Here we are talking about Se, Te, Au and Ag (we referred to the sentence at lines 794-795 “distribution of clausthalite, tellurium, hessite and gold/electrum grains in the bornite-rich shell”). Se and Te are considered as critical metals for energy transition; Au and Ag are precious metals.

Line 809-850 – Yes, we know that the behavior of these metals still needs to be clarified (see lines 849-850). However, the discussion was introduced to stimulate further investigation on VMSs from Liguria and Tuscany that could be useful for the global discussion on geochemistry of VMSs and SMSs.

Line 851 – Ok, the sentence was rephrased.

Line 864 – Ok, removed.

Line 871 – Ok, the sentence was corrected.

Line 874-881 – Ok, the sentence was corrected.

Line 887-893 – The story of progressive exhumation/hydration is based on geological data (crosscutting relationships between serpentinite-gabbro-dolerite described in the text) and petrographic data (coarse-grained gabbro dykes/sills cannot crystallize at the same depth and host rocks thermal state, of very fine-grained porphyritic dolerite dyke; degree of hydration/alteration of different rock types). Then, our interpretation can be considered speculative, but I don’t see much difference with the speculation of some petrologists that base their mantle models on trace elements in few relic crystals in serpentinized peridotites.

Evidence for sequential intrusion of gabbro and basalt throughout already serpentinized peridotites was found also in Hole U1309B, IODP Site 1309 (Expedition 304; https://doi.org/10.2204/iodp.proc.304305.103.2006). Of course, our hypothesis is based on first order evidence (geology and petrography). Hopefully, future petrologic studies will provide (or not!) additional constraints.

Finally, available petrologic data indicate that serpentinization of Northern Apennine peridotites occurred at temperature below 320 °C (Cannaò et al., 2024 https://doi.org/10.1016/j.chemgeo.2023.121899).

Line 894 – Ok, the sentence was rephrased.

Line 908-912 – Yes, this mineralogical assemblage indicates quite high temperatures (according also to Colat work). These silicates are intimately intergrown with bornite-chalcopyrite aggregates (see chapters 3.2.2 and 3.3.2). This is one of the main pieces of evidence for hydrothermal reworking by influx of new hot fluids (magmatic? modified seawater triggered by new magma chambers?). We hope to answer in next contributions after an exhaustive EPMA, LA-ICPMS, MC-ICPMS investigation. For the aim of this review, we believe that the description provided is sufficient to understand the context.

Line 914 – Ok, “master” was changed with “main”.

Line 941 – Ok, we removed “3D”. However, the geological cross sections in Figure 10 intersect the MVC deposit in several direction providing an “almost” 3D view. Obviously, this is not a software-generated 3D geological model!

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors, dear Editor,

I have re-checked the manuscript. The authors definitely improved it, however, it is still too long and and some parts, hard to follow. The suggested sketch drawings/mineral precipitation series would e.g., help, but only one was prepared. It would be good, if the Authors could check the text carefully, where they could be more concise.

Otherwise, I still find it is an interesting and important documentation of the studied VMS deposits, therefore it'll be worth to publish it in Minerals. Just it needs some more polishing.

Comments on the Quality of English Language

Only minor editing is needed.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

I have now rechecked the revised manuscript version made by authors. This version shows substantial improvement from the last version, and can be accepted. Congratulation!

Best regards,

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have provided the necessary corrections to the manuscript and provided satifactory reply to the comments. The VMS deposits of Tuscany appear really interesting and I will be looking forward for futur publications. I recommend publication.