Mineralogy and Mineral Chemistry of Dioritic Dykes, Quartz Diorite Enclaves and Pyroxene of the Sungun Cu-Mo Porphyry Deposit, East Azerbaijan, Iran

Round 1

Reviewer 1 Report

The authors present data on the mineralogy and mineral chemistry of Sungun Cu-Mo 3 porphyry deposit. They found the oxygen fugacity during the rock forming is anomaly higher, which help to locate the formation of diorite. Results from the current study is consistent with literature and this works adds up the understanding of the origin of the Sungun Cu-Mo porphyry magmas. The manuscript is well written and provides sufficient data to support their conclusions. I have only a few minor comments, as shown below:

 

Fig. 3 f) and g), the numbers on the scale bar are unclear.

 

Fig. 4 a), One of the “Plg” points to the number by the marker pen, which should be removed. d) The “Plg” arrow is reversed and is hard to read.

 

Table 1, what do the stars mean in the table?

 

Fig. 7-9, error analysis for all presented data should be given.

 

Fig. 9 a)-d), the legend in the figure is too small to read.

 

Line 246, I cannot find the “XXXXX diagram” in ref [22].

 

Line 294, 297 and 324, “tchermak” has never appeared in any literature I’ve read. Please make sure it is correct.

 

Line 362 and 366, please add unit of temperature for your equations.

 

Line 402, same as above, the unit of pressure is missing.

Author Response

Dear reviewer

1. Writing and scientific errors were eliminated as much as possible.
2. Some parts have been replaced or deleted.
3. Other items have been modified in the text of the article.

Best regards,

Amin kamali

Reviewer 2 Report

I will get straight to the 2 principal issues that I have with this paper. 

Firstly, this is a clear adakite-high-Nb basalt environment that the authors for some reason completely failed to recognize. Sungun porphyry is a beautiful adakite pluton with absolutely classic adakitic Sr/Y ratios in excess of 40 and more. Numerous lamprophyric dikes are high-Nb basalts (HNBs) with Nb contents over 30 ppm, or so. This distinctive pair (adakite + high-Nb basalt) is associated with world-class Cu(Mo, Au) porphyry deposits through out the world's subduction terranes and collision belts. Adakites host giant Cu-Mo-Au deposits in the Andes (Escondida, El Teniente, Chuquicamata, Bajo de la Alumbrera), Philippines (Santo Tomas, Tampakan and many others), Indonesia (Batu Hijau, Grasberg) and are frequently associated with high-Nb dikes (which people keep erroneously calling lamprophyres). High-Nb basalts are also associated with large mineralized systems in the Philippines and Papua New Guinea (Porgera, for example).

I suggest that authors take a look at some really good and detailed summaries of geochemistry, petrogenesis and metallogeny of adakite and high-Nb basalt magmas and add these to their reference list:

Drummond M.S. et al. (1996). Petrogenesis of slab-derived trondhjemite-tonalite-dacite/adakite magmas. Transactions of the Royal Society of Edinburgh, v.87, p. 205-215.

Kepezhinskas P. et al. (2022). Adakites, high-Nb and copper-gold deposits in magmatic arcs and collisional orogens: an overview. Geosciences, v. 12, 29.

Kepezhinskas N. et al. (2020). Petrology and geochemistry of alkaline basalts and gabbroic xenoliths from Utila Island (Bay Islands, Honduras): insights into back-arc processes in the Central American Volcanic Arc. Lithos, v. 352-353, 105306.

Another issue is related to the oxygen fugacity values of -13 to -15 cited through out the paper, including the abstract. What buffer is used to calculate these values - FMQ? If this is the case, this is a uniquely reducing environment that is rarely associated with Cu porphyry deposit formation. Authors are advised to review their oxygen fugacity estimates and specify what buffer systems are used. Readers definitely need more specific information on this subject.

Figure 1 is quite confusing and difficult to read. The senior author has much better simplified tectonic maps of Iran in his earlier papers, which will be substantially more helpful for an outsider to navigate through the fairly complex tectonic mozaic of Iranian collisional sutures, magmatic arcs, accretionary belts, etc.

Line 50 - what are the other "world-class porphyry copper deposits" in this magmatic belt? What are their tonnages and grades?

Line 52 - are their any Mo and/or Au associated with Sungun copper deposit?  If yes, what are the grades for these metals?

Line 76 - what are other intrusive lithologies in the Sungun monzodiorite poprhyry? What are the geologic relationships between them?

I also think that some representative chemical analyses (majors + traces) of both felsic porphyry and cross-cutting dikes will be very helpful in this manuscript to put this whole story into the adakite-high-Nb basalt perspective. Where, as I firmly believe, these very interesting rocks truly belong.

 

 

 

Author Response

Dear reviewer

1. Writing and scientific errors were eliminated as much as possible.
2. Some parts have been replaced or deleted.
3. Other items have been modified in the text of the article.
4. Regarding the adakite or non-adakite nature of the Sungun deposit and the high amounts of strontium and niobium, it should be noted that: Strontium is very mobile in the conditions of hydrothermal alteration and it is not possible to determine whether the system is adakitic or not based on its values and ratios. On the other hand, Niobium and other rare earth elements dominate mobile porphyry systems in hydrothermal alteration conditions, which have been discussed in several articles. Basically, to prove the adakitic nature of porphyry systems, it is necessary to design new diagrams that utilize immobile or less mobile elements. In addition the discrimination diagrams in the manuscript do not confirm the adakitic nature of the magmas, since the samples do not plot in the adakite fields.

Best regards,

Amin kamali

Round 2

Reviewer 2 Report

The authors did a thorough and comprehensive review of their munuscript. Which is now ready for publication. 

Author Response

Dear reviewer

1. Writing and scientific errors were eliminated as far as possible.
2. Xenocrysts was left out of the article's title and body of text and was regarded as a typical mineral coexisting in equilibrium with diorite.
3. Some parts have been replaced or deleted.
4. Other items have been modified in the text of the article.

                                Best regards,

Amin kamali

Author Response File: Author Response.docx