Episodic Precipitation of Wolframite during An Orogen: The Echassières District, Variscan Belt of France

Round 1

Reviewer 1 Report

The article is very interesting because it proposes a new genetic model for multi-stage wolframite (tungsten) mineralization within the orogenic Variscan belt in Europe. The authors base their model on the results of LA-ICP MS isotope U-Pb age studies of three generations of monazite and one generation of rutile, which are considered paragenetic minerals for three generations of wolframite ("a-c" - where "a" is the oldest wolframite generation and "c" the youngest). They present interesting discussion of various geotectonic environments for the Variscan orogen and related subsequent wolframite crystallization ranging from over 360 Ma to approx. 310 Ma.

Below are some of the main comments to the reviewed article:

• Rutile U-Pb geochronology are complicated because the uranium concentrations are typically low (<15 ppm), and common Pb contamination can be high, (e.g. Schmitt and Zack 2012; Taylor et al., 2012). The rutile should be more precisely described in terms of mineral characteristics, as this could have influenced the results of the analyzes. Rutile analyzed via LA-ICP MS cannot resolve internal grain [age] zonation. Please state what were the uranium contents in studied rutile? Did the rutile show zonal structure and did it have other mineral inclusions?

• The article discusses the results of the LA-ICP MS research in general without much detail, but the EPMA results are not discussed at all. Description should be completed in this regard. The lower limits of detection for the various elements tested should also be given. Remove results below the lower detection level from Appendix 1.

• Undoubtedly, it is necessary to supplement the article in terms of including descriptions characterizing ore mineralization in the examined places. This information can be compiled in the form of a collective table containing a list of ore minerals typical for each of the studied areas. Data from other works should also be cited.
• As a new model for the crystallization of three successive wolframite generations in the orogenic belt of European Variscides is presented, it should be supplemented with citations of works also from the area of ​​the central and eastern part of European Variscan belt. In these areas, tungsten mineralization is accompanied by sulphide mineralization (major of molybdenite and chalcopyrite) as well as with REY-Nb-U-Th. There are also peraluminous and hybrid magmas responsible for Mo-Cu-W and / or W-Sn-Mo-REY-Nb mineralization. Some examples are worth citing.

• Some figures need to be corrected or completed (Figs. 1B, 2A, 2F, 2F 'and 6A-D). Details are given in the manuscript.
• Reference citations in the text as well as the Reference cited list must be presented in accordance with MINERALS requirements.

Other comments have been made directly on the manuscript.

Comments for author File: Comments.pdf

Author Response

Please, see attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

Your manuscript contains valuable new age data on the Echassières District, France. However, Your discussion contains much more, I guess, it is based on Your previous, detailed experience gathered in this region. Therefore, I suggest either to include more information in the results chapter, which support Your discussion, or to eliminate those parts from discussion, which are not based on the results of the present study. It is clear, that Your interpretation about the evolution of the Echassières District is interesting and valuable, just I suggest to find the optimal way of presentation.

Besides, a few other comments are listed below.

Introduction
-the first paragraph is unclear, please, revise.
-please, emphasise more the research questions, why is this topic unique, what are the main shortages of this study area?
-it is not clear, why this research is needed, what kind of new information is obtained? (If we look at fig 5, quite a lot studies were dealing with the age of the various formations in this region...)

Geological setting
-Fig1B please, indicate a reference for this map
-a few words about the underlying/host rock series, in which the magmatites were intruded, would be useful in this chapter.

Tungsten Mineralization
-a diagram indicating the compositional range of the different wolframite types would help the reader to easier understand this chapter

Materials and Method
-why fig 3 is before fig 2?
-please, include the detailed measurement conditions in chapter 4.2.

Results
-why figure 4 is found only on page nr 10 (after fig 5)? it is cited in the text much earlier.
-what about quartz veins (containing wolframite a)? please, have a sub-chapter about this vein type, too
-please, include a bit more details on petrography, as the reader must be convinced about the textural relationships of the analysed monazite and rutile crystals and the ore minerals...

Discussion
-chapter 6.1.a contains a discussion, which is not based on the observations presented in this paper. Thus I'm not sure, this should be a part of this manuscript. Or alternatively, please, include detailed petrography in this manuscript, in order to support this part of the discussion
-it is not clear, how do we know, that wolframite a is older, than 360 Ma?
-fig 4a: on this sketch it is shown, that quartz veins contain either wolframite a and b. However, in the text it was not written. Please, clarify this issue.
-fig 4b: how can we have older ages in rutile and monazite 2, than the host granite? please, explain this!
-chapter 6.2.a contains again a discussion of a phenomenon, about which results were not really presented. I see, that You have a lot of previous work on this study area and thus have already collected a lot of knowledge on this topic, but the readers have to understand this manuscript in itself and has to have enough information, which support Your statements.
-chapter 6.3: this part of discussion is ver interesting, but is not really based on the described research results. It is most likely based on Your other, earlier investigations. Therefore, I suggest to remove this part from this manuscript.

Author Response

Please see attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors presented a revised version of the article which took into account the previous comments. They also improved graphic figures. I believe the article is suitable for publication in Minerals as it stands.

It is a very interesting article that should be of interest to the readers.

Reviewer 2 Report

Dear Authors,

the revised version of Your manuscript has taken into consideration both two reviewers' comments, therefore it is significantly developed. The included new table 1 is clearly helpful for the readers to follow Your way of thinking and thus to support Your statements. The included new references are also useful.

To sum up, I find this manuscript suitable for publication in Minerals.