Mineral Characteristics and the Mineralization of Leptynite-Type Nb–Ta Ore Deposit in the Western Qilian Orogenic Belt
Round 1
Reviewer 1 Report
Dear authors:
Your manuscript is read with great effort, but it is difficult to review every part of the manuscript because the English expression is very poor. I highlighted and corrected some in the pdf. Therefore, extensive editing of English language and style is needed. I put forward the following comments for your revision.
Abstract: The english expression is poor and modified by the reviewer. Please note that the last part of the abstract is not clear: what is the formation age of the deposit? Neoproterozoic, Caledonian, or later? Are the 17.90% of Nb in titanium magnetite-maghemite also independent Nb-Ta minerals?
P6l144: what is the meaning of The experimental error is ±10−4? For elemental concentration or mineral percentage?
P6l146-150 Also for table 1: what are the efficient decimal digits? According to the current technology, 2 decimal digits are possible.
Table 1: according to list of IMA minerals, many mineral names in the table should be corrected. For REE minerals, the dominating element should be indicated in the name, e.g., Bastnäsite-(Ce). Please refer to mindat.org.
Table 1: What is the difference between ilmenorutile and Nb-rutile? Both are Nb-bearing rutile instead of individual minerals. Content% should be specified: wt.% or vol.%?
Table 2: grain size % should be specified: grain number%, grain volume% or grain weight%
Fig. 4, 5, 6: th green color of labels are not good for black and white images, pure black or white are recommended.
Table 3: the table need not be split (continued), single numbers in the table should not be separated to 2 lines.
Table 3: the variation range of the data are too big. Please make sure that reliable analytical data are presented. Please add the empirical formula for each mineral to identify the mineral. For example, the Nb/Ta contents of microlite may be in the range of pyrochlore.
Fig. 7: how the Nb partition % of veinstone can be close 100% while having Nb2O5 contents near 0?
Table 4: the column of Nb2O5 contents in minerals should be before the column of Nb2O5 contents in ores because the product of the first two columns’ data is equal to the third column.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer,
Thank you very much for your comments and suggestions. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Meanwhile, we have applied for language editing services of editorial office to polish our paper. It is a reason to delay to return reviewed manuscript. Here, we attached revised manuscript in the formats of PDF, for your approval. The main corrections in the paper and the responds to the reviewer’s comments are as follows.
Point 1: Abstract: The english expression is poor and modified by the reviewer. Please note that the last part of the abstract is not clear: what is the formation age of the deposit? Neoproterozoic, Caledonian, or later? Are the 17.90% of Nb in titanium magnetite-maghemite also independent Nb-Ta minerals?
Response 1: Thanks for this suggestion. We have applied for language editing services of editorial office to polish our paper. Please see if the revised version met the English presentation standard. About the last part of the abstract, we have revised it accordingly as follows (Line 18-44, revised version of the manuscript).
“The other 17.90% Nb as isomorphism was dispersed in titanium magnetite-maghemite, and an-other 13.00% Nb was dispersed in gangue minerals. Nb minerals are formed mainly by two metallogenesis stages. The first stage is magmatic genesis to form four Nb minerals, euhe-dral-subhedral fergusonite, polycrase, pyrochlore, and microlite, which are crystallized within or between primary minerals, such as quartz and feldspar. Late alteration phenomena are locally observed. The second stage is the hydrothermal genesis of columbite, anhedral fergusonite, Nb-rutile and aeschynite, which are dispersed in the fissures of the wall rocks as irregular veins and lump assemblages, and are closey associated with metasomatic chlorite, albite, and secondary quartz. Furthermore, direct metasomatism among different Nb minerals is also found at the local scale. The Nb percentage of these two Nb mineral mineralization types is approximately equal, which reflects two main mineralizing periods. The first stage of mineralization occurred in the Neoproterozoic Era (834-790 Ma). Magmatism of this period produced early niobium and formed fergusonite, polycrase, pyrochlore,microlite, and zircon. The initial enrichment of Nb, Ta, and other rare metals occurred during this stage. The second stage of mineralization occurred in the Caledonian period (490-455 Ma). Large-scale and intense tectonic-magmatic thermal events oc-curred in the western part of the QOB due to the plate subduction and convergence (510-450 Ma). Hydrothermal activity in this period formed columbite, fergusonite, Nb-rutile, and aeschynite. Moreover, rare metal elements in the Nb-bearing rocks activated and migrated at short distances, forming in situ Nb–Ta-rich ore deposits.”
Point 2: P6l144: what is the meaning of The experimental error is ±10−4? For elemental concentration or mineral percentage?
Response 2: The meaning of the experimental error is ±10−4 for the mineral percentage.
Point 3: P6l146-150 Also for table 1: what are the efficient decimal digits? According to the current technology, 2 decimal digits are possible.
Response 3: All the samples weigh approximately 5035 kg in our study. Each sample weighed approximately 5.6 kg on average. We sorted all minerals from the rock samples. When calculating the mineral percentages, the results reached four decimal digits for some minerals with particularly low contents.
Point 4: Table 1: according to list of IMA minerals, many mineral names in the table should be corrected. For REE minerals, the dominating element should be indicated in the name, e.g., Bastnäsite-(Ce). Please refer to mindat.org.
Response 4: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 5: Table 1: What is the difference between ilmenorutile and Nb-rutile? Both are Nb-bearing rutile instead of individual minerals. Content% should be specified: wt.% or vol.%?
Response 5: There are differences in the contents of Nb, Fe, and Ti between ilmenorutile and Nb-rutile, as well as in the structure. The chemical formulae of ilmenorutile and Nb-rutile are (Ti,Nb,Ta,Fe)O2 and TiO2, respectively. Moreover, the contents of Nb2O5 in ilmenorutile and Nb-rutile are 5.10-26.52% and 0.38-2.88%, respectively. The Content% is wt.%. We have added the corresponding content to the paper (Line 208-211, revised version of the manuscript).
Point 6: Table 2: grain size % should be specified: grain number%, grain volume% or grain weight%
Response 6: The grain size % is grain volume% and we have revised this. Please check it.
Point 7: Fig. 4, 5, 6: the green color of labels are not good for black and white images, pure black or white are recommended.
Response 7: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 8: Table 3: the table need not be split (continued), single numbers in the table should not be separated to 2 lines.
Response 8: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 9:Table 3: the variation range of the data are too big. Please make sure that reliable analytical data are presented. Please add the empirical formula for each mineral to identify the mineral. For example, the Nb/Ta contents of microlite may be in the range of pyrochlore.
Response 9: Thanks for this suggestion. The metallogenic process of the object of study is complex and there are multiple stages superimposed. Therefore, the element content varies in a wide range. The data presented in this article are reliable analytical test data. Meanwhile, the empirical formula is also added in Table 3.
Point 10: Fig. 7: how the Nb partition % of veinstone can be close 100% while having Nb2O5 contents near 0?
Response 10: We have modified Figure 7 (Line 431, revised version of the manuscript). Please check it.
Point 11: Table 4: the column of Nb2O5 contents in minerals should be before the column of Nb2O5 contents in ores because the product of the first two columns’ data is equal to the third column.
Response 11: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
We look forward to hearing from you in due time regarding our submission and to respond to any further questions and comments you may have. Thanks for your time.
Best wishes
Author Response File: Author Response.pdf
Reviewer 2 Report
· The manuscript “Mineral Characteristics and Mineralization of Leptynite Type Nb-Ta Ore Deposit in Western Qilian Orogenic Belt” by Junpeng Yu and other authors is a typical research focus on niobium minerals in the studied deposit. The manuscript is rather descriptive, well-illustrated, generally well-organized and entertaining. The authors show new evidences on the formation of Yushishan deposit. But some figures in this manuscript should be improved before acception.
· Particular comments:
· Page 2 Figure 1: Some symbols of strata in the figure are not consistent with the text in Line 74-78, please check and correct them. It is better to add the stratigraphic age in the legend (e.g., Cambrian-Ordovician Lapeiquan group).
· Figure 3-6 : The notes in these figures are not clear, please rewrite them. It is better list the abbreviation of mineral names in these pictures (e.g., Bt as biotite) and list full mineral names in the caption (e.g., Bt = biotite).
· Page 2 line 80: It should be “Yanshanian”. What is “Warrician”, please check it.
· Page 5 lines 130-132: the “lattice double crystal orthoclase” should be “Microcline”. what is “SEM electron microscopic”, please check it.
· Page 6 Table 2: it should be “total”.
· Page 7 line 191: what is “polycraseor”.
· Page 12 line 316: it should be “The total niobium accounts contributed to the ores in Nb-rutile and ilmenorutile is only 7.43%”.
· Page 13 Figure 7: please add notes to show what the columnar and prismatic symbols represent, respectively.
· Page 15 line 409: is the Neogene correct? It should be Neoproterozoic.
Author Response
Dear reviewer,
Thank you very much for your comments and suggestions. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Meanwhile, we have applied for language editing services of editorial office to polish our paper. It is a reason to delay to return reviewed manuscript. Here, we attached revised manuscript in the formats of PDF, for your approval. The main corrections in the paper and the responds to the reviewer’s comments are as follows.
Point 1: Page 2 Figure 1: Some symbols of strata in the figure are not consistent with the text in Line 74-78, please check and correct them. It is better to add the stratigraphic age in the legend (e.g., Cambrian-Ordovician Lapeiquan group).
Response 1: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 2: Figure 3-6 : The notes in these figures are not clear, please rewrite them. It is better list the abbreviation of mineral names in these pictures (e.g., Bt as biotite) and list full mineral names in the caption (e.g., Bt = biotite).
Response 2: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 3: Page 2 line 80: It should be “Yanshanian”. What is “Warrician”, please check it.
Response 3: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 108, revised version of the manuscript).
“Magmatic activity in this region mostly occurred in the Caledonian, followed by the Variscan and Yanshanian.”
Point 4: Page 5 lines 130-132: the “lattice double crystal orthoclase” should be “Microcline”. what is “SEM electron microscopic”, please check it.
Response 4: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 171-173, revised version of the manuscript).
”(F-H) Leptynite-type ore (black minerals are mainly magnetite; anhedral granular quartz, sub-hedral–anhedral granular orthoclase, plagioclase biotite, and microcline in the rocks). “
Point 5: Page 6 Table 2: it should be “total”.
Response 5: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 6: Page 7 line 191: what is “polycraseor”.
Response 6: Thanks for this suggestion. The “polycraseor” is “polycrase”. We have revised this. Please check it.
Point 7: Page 12 line 316: it should be “The total niobium accounts contributed to the ores in Nb-rutile and ilmenorutile is only 7.43%”.
Response 7: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 8: Page 13 Figure 7: please add notes to show what the columnar and prismatic symbols represent, respectively.
Response 8: Thanks for this suggestion. We have made corrections based on the reviewer’s comment (Line 431, revised version of the manuscript).
Point 9: Page 15 line 409: is the Neogene correct? It should be Neoproterozoic.
Response 9: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
We look forward to hearing from you in due time regarding our submission and to respond to any further questions and comments you may have. Thanks for your time.
Best wishes
Author Response File: Author Response.pdf
Reviewer 3 Report
Review of “Mineral Characteristics and Mineralization of Leptynite Type Nb-Ta Ore Deposit in Western Qilian Orogenic Belt” by Yu et al.
The authors studied Nb-Ta ore deposits in the Western Qilian Orogenic Belt of China. They use textural and compositional data to identify the distribution of Nb and Ta, and present a model of ore-genesis.
Although the paper has merits and is potentially of interest for the readers of Minerals, the quality of the presentation must be improved before the manuscript can be published.
The quality of the language is rather poor, and not up to standard, which makes reading complicated at times. I point out many of the issues below and in the annotated manuscript, but they are too many to indicate.
Several geological terms are not used accurately (check the correct terms in English), and there are many sentences that do not stand from the logical viewpoint, and need re-writing.
You cannot expect the reviewers to fix a manuscript that is not ready for submission.
In the figures, the readability of labels is also an issue. Notably the use of colours that do not offer strong contrast, as well the small font size.
Detailed comments:
Line 11. Delete “of” after “eight”.
Line 13. Replace “deposit in” with “occur”. Delete “percentage”.
Line 16. Replace “gangues” with “gangue minerals”.
Line 20. Replace “in the local scope” with “at the local scale”.
Line 23. The term paragenesis is not used correctly in this sentence, and the meaning is unclear. Re-write.
Line 38. High, instead of higher.
Line 41. Nb-Ta ore deposits occur as magma- or sediment-hosted,
Line 48. What is the meaning of “colligated” and the sentence more in general?
Line 50. Delete “In recent years,”.
Line 55-56 (and elsewhere in the manuscript). What is the meaning of “state” and “mineral-embedded properties”?
Line 60. Replace “It” at the beginning of the sentence with “our study”.
Line 77. Replace “embeds in” with “is hosted by”.
Line 80. “Intermediate-felsic”, instead of Medium-acidic”.
Line 81. If they are magmatic, use the term dyke, instead of vein.
Line 83. What is the meaning of “approaches”?
Line 84. Check these directions.
Line 92-93. I do not understand these geographical directions.
Line 98-99. The meaning is unclear. Xenoliths become more abundant towards the margin of the intrusion? Also, is 481.3 Ma the age of the intrusion, or the xenoliths?
Line 108. What is the meaning of convergence and divergence in this context? It is not clear from the images.
Line 118. Instead of using etc., list the minerals identified.
Line 119. Is this the size of magnetite?
Line 302. What are all the percentages mentioned in brackets for each mineral? Their total abundance is reported to be 0.2572%. Specify.
Line 323. The term “mineralogical mechanism” is unclear. Does it refer to the genetic mechanism, or perhaps the mineral occurrence? Specify.
Line 334. Use the term titanite instead of sphene (older term).
Line 378-379. Diagenesis is very different from magma processes. Review your terminology.
Line 397. What r the “archives of formation background”? Re-write this sentence.
Lines 401-403. This sentence is unclear. “Split” is supposedly referring to rifting. Also, what formed “at the same time”?
Line 409. An age of 834-790 Ma sure is not Neogene…
Line 412. Here the term “diagenesis” is used, but the authors have described magmatic and hydrothermal stages so far. Correct the terminology.
Line 455-456. This point (3) reads a bit like a heading, not having a verb or a full stop at the end. However, points (1) and (2) above were not organised this way. The style should remain consistent.
Figure 3. As a general rule, red labels in figure are difficult to see. Rather use white or black labels for all the figures.
Comments for author File: Comments.pdf
Author Response
Dear reviewer,
Thank you very much for your comments and suggestions. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Meanwhile, we have applied for language editing services of editorial office to polish our paper. It is a reason to delay to return reviewed manuscript. Here, we attached revised manuscript in the formats of PDF, for your approval. The main corrections in the paper and the responds to the reviewer’s comments are as follows.
Point 1: Several geological terms are not used accurately (check the correct terms in English), and there are many sentences that do not stand from the logical viewpoint, and need re-writing.
Response 1: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Meanwhile, We have applied for language editing services of editorial office to polish our paper. Please see if the revised version met the English presentation standard.
Point 2: In the figures, the readability of labels is also an issue. Notably the use of colours that do not offer strong contrast, as well the small font size.
Response 2: Thanks for this suggestion. We made corrections to the figures based on the reviewer’s comment. Please check it.
Point 3: Line 11. Delete “of” after “eight”.
Response 3: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 4: Line 13. Replace “deposit in” with “occur”. Delete “percentage”.
Response 4: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 5: Line 16. Replace “gangues” with “gangue minerals”.
Response 5: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 6: Line 20. Replace “in the local scope” with “at the local scale”.
Response 6: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 7: Line 23. The term paragenesis is not used correctly in this sentence, and the meaning is unclear. Re-write.
Response 7: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 25-29, revised version of the manuscript).
“The second stage is the hydrothermal genesis of columbite, anhedral fergusonite, Nb-rutile and aeschynite, which are dispersed in the fissures of the wall rocks as irregular veins and lump as-semblages, and are closey associated with metasomatic chlorite, albite, and secondary quartz.”
Point 8: Line 38. High, instead of higher.
Response 8: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 9: Line 41. Nb-Ta ore deposits occur as magma- or sediment-hosted,
Response 9: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 54-56, revised version of the manuscript).
“Nb–Ta ore deposits occur as magma- or sediment-hosted, according to the hosting rocks [2], and the magmatic deposit is the most important.”
Point 10: Line 48. What is the meaning of “colligated” and the sentence more in general?
Response 10: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 63, revised version of the manuscript).
“moreover, some regard it by different mineralizations [12-13].”
Point 11: Line 50. Delete “In recent years,”.
Response 11: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 12: Line 55-56 (and elsewhere in the manuscript). What is the meaning of “state” and “mineral-embedded properties”?
Response 12: Thanks for this suggestion. The “state” is replaced by “occurrence mode” and the meaning of “mineral-embedded properties” is “mineral-disseminated properties”. We have made corrections based on the reviewer’s comment and the results are as follows (Line 76-78, revised version of the manuscript).
“On the other hand, the occurrence mode of Nb in the ore rocks and mineral-disseminated properties have not been systematically studied.”
Point 13: Line 60. Replace “It” at the beginning of the sentence with “our study”.
Response 13: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 14: Line 77. Replace “embeds in” with “is hosted by”.
Response 14: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 15: Line 80. “Intermediate-felsic”, instead of Medium-acidic”.
Response 15: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 16: Line 81. If they are magmatic, use the term dyke, instead of vein.
Response 16: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 109, revised version of the manuscript).
“Intermediate-felsic magmatic rocks formed as stocks or dykes.”
Point 17: Line 83. What is the meaning of “approaches”?
Response 17: Thanks for this suggestion. we have revised it accordingly as follows (Line 112-116, revised version of the manuscript).
“A series of east–westward, north–east–eastward, and north–west–westward, mainly translation fault systems, have been formed under multi-stage tectonic activities of the Altun Tagh Great Fault and other faults.”
Point 18: Line 84. Check these directions.
Response 18: Thanks for this suggestion. we have revised it accordingly as follows (Line 112-116, revised version of the manuscript).
“A series of east–westward, north–east–eastward, and north–west–westward, mainly translation fault systems, have been formed under multi-stage tectonic activities of the Altun Tagh Great Fault and other faults.”
Point 19: Line 92-93. I do not understand these geographical directions.
Response 19: Thanks for this suggestion. we have revised it accordingly as follows (Line 123-125, revised version of the manuscript).
“The main Nb–Ta hosting unit is the Aoyougou Formation (Cha), which extends west–northwest to the east–northeast.”
Point 20: Line 98-99. The meaning is unclear. Xenoliths become more abundant towards the margin of the intrusion? Also, is 481.3 Ma the age of the intrusion, or the xenoliths?
Response 20: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 128-134, revised version of the manuscript).
“The main granite body exposed in the mine area is Ordovician diorite granite (Figure 2), which intruded into the strata of the Aoyougou Formation. It formed at approximately 481.3±1.7 Ma in the early Ordovician period [21]. Contact with the wall rocks is relatively secant and sometimes undulated. Some enclosure edges are enriched with felsic minerals. The wall rock xenoliths become more abundant towards the margins of the intrusion.”
Point 21: Line 108. What is the meaning of convergence and divergence in this context? It is not clear from the images.
Response 21: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 147, revised version of the manuscript).
“It shows a trend of slight divergence to the east and convergence to the west.”
Point 22: Line 118. Instead of using etc., list the minerals identified.
Response 22: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 157-158, revised version of the manuscript).
“The main minerals are quartz, plagioclase, and orthoclase, followed by chlorite, muscovite, biotite, titanite, and magnetite (Figure 3F).”
Point 23: Line 119. Is this the size of magnetite?
Response 23: The grain size is the size of magnetite. We have revised it accordingly as follows (Line 160-161, revised version of the manuscript).
“The grain size of magnetite is mostly less than 0.2 mm, and occur as vein-like, irregular agglomerate, and disseminated forms (Figure 3H, 3J, and 3K).”
Point 24: Line 179. Are these “fissures” cracks in orthoclase, where fergusonite precipitated?
Response 24: Thanks for this suggestion. We have revised it accordingly as follows (Line 247-248, revised version of the manuscript).
“The anhedral granular fergusonite, albite and columbite are hosted in the orthoclase fissures (Figure 5E).”
Point 25: Line 300. Main mineral hosts for Nb? Or “modes of occurrence”?
Response 25: Thanks for this suggestion. The “occurrence states of Nb” is the “modes of occurrence of Nb”. We have revised it accordingly as follows (Line 405, revised version of the manuscript).
“There are three main modes of occurrence of Nb.”
Point 26: Line 302. What are all the percentages mentioned in brackets for each mineral? Their total abundance is reported to be 0.2572%. Specify.
Response 26: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 407-410, revised version of the manuscript).
“They are mainly fergusonite (0.0248 wt.%), columbite (0.0126 wt.%), polycrase (0.0231 wt.%), Nb-rutile (0.1817 wt.%), aeschynite (0.0066 wt.%), pyrochlore (0.0032 wt.%), micro-lite (0.0024 wt.%) and ilmenorutile (0.0028 wt.%).”
Point 27: Line 323. The term “mineralogical mechanism” is unclear. Does it refer to the genetic mechanism, or perhaps the mineral occurrence? Specify.
Response 27: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 437-439, revised version of the manuscript).
“Since the discovery of the Yushishan Nb–Ta ore deposit in 2011, its mineral occurrence has been investigated by several researchers [15,16,19,28].”
Point 28: Line 334. Use the term titanite instead of sphene (older term).
Response 28: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 29: Line 378-379. Diagenesis is very different from magma processes. Review your terminology.
Response 29: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 503-504, revised version of the manuscript).
“The first type is magmatic mineralization”.
Point 30: Line 397. What r the “archives of formation background”? Re-write this sentence.
Response 30: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 526-528, revised version of the manuscript).
“Furthermore, we combine the archives of the recovery and formation background of the leptynite protoliths [15,16,19,22].”
Point 31: Lines 401-403. This sentence is unclear. “Split” is supposedly referring to rifting. Also, what formed “at the same time”?
Response 31: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 530-532, revised version of the manuscript).
“The block of the western part of Central Qilian rifted during the Neoproterozoic Era (834-790 Ma). The Nb-rich intermediate-felsic magmatic rocks were formed in the Yushishan.”
Point 32: Line 409. An age of 834-790 Ma sure is not Neogene…
Response 32: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 539-541, revised version of the manuscript).
“These three tectonic units were in the process of continental rifting during the middle and late Neoproterozoic Era (834-790 Ma) (Figure 8A), corresponding to the rifting stage of the Rodinia supercontinent [30,32,38-43].”
Point 33: Line 412. Here the term “diagenesis” is used, but the authors have described magmatic and hydrothermal stages so far. Correct the terminology.
Response 33: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 546-547, revised version of the manuscript).
”Its petrogenic age is 834-790 Ma [15-16,22], which corresponds to the tectonic setting of continental rifting in the region”.
Point 34: Line 422. Which ones? Specify.
Response 34: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 564-566, revised version of the manuscript).
“The Quanji Block in the northern boundary of Qaidam Basin, the western part of the Central Qilian Block, and the northern boundary of Altun Tagh Block subducted and converged during the Caledonian period (510-450 Ma)”.
Point 35: Line 455-456. This point (3) reads a bit like a heading, not having a verb or a full stop at the end. However, points (1) and (2) above were not organised this way. The style should remain consistent.
Response 35: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 36: Figure 3. As a general rule, red labels in figure are difficult to see. Rather use white or black labels for all the figures.
Response 36: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
We look forward to hearing from you in due time regarding our submission and to respond to any further questions and comments you may have. Thanks for your time.
Best wishes
Author Response File: Author Response.pdf
Reviewer 4 Report
Dear author,
Here is enclosed your draft including all my remarks and suggestions to enhance the quality of it.
You draft may need some recheck by fluent English writer.
*The introduction section must state the motivation for your work and prepare reader for the structure of the paper. It has also to show the need for your work as an opposition between what other author, such as Jiang et al. (2022), currently had and what value you want to add to this asset.
Best regards,
Comments for author File: Comments.pdf
Author Response
Dear reviewer,
Thank you very much for your comments and suggestions. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Meanwhile, we have applied for language editing services of editorial office to polish our paper. It is a reason to delay to return reviewed manuscript. Here, we attached revised manuscript in the formats of PDF, for your approval. The main corrections in the paper and the responds to the reviewer’s comments are as follows.
Point 1: The introduction section must state the motivation for your work and prepare reader for the structure of the paper. It has also to show the need for your work as an opposition between what other author, such as Jiang et al. (2022), currently had and what value you want to add to this asset.
Response 1: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 65-87, revised version of the manuscript).
“The Yushishan deposit is a large Nb–Ta ore deposit which was discovered in the western part of the central Qilian Mountain. It is a strata-bound ore deposit formed in the Precambrian metamorphic leptynite strata [14-16]. The geological characteristics, protolith and age of mineralization of the deposit have been studied previously [14-22]. Jiang et al. (2022) conducted a series of studies on the deposit [16]. They mainly discussed the geo-chemical characteristics of leptynite, the diagenetic age, the characteristic of the Nb–Ta orebodies, and the ore genetic model of the Yushishan Nb–Ta deposit [16]. However, ore minerals containing Nb, Ta, and other rare metal elements in this deposit have not been studied in detail. Therefore, there are still open questions. On the one hand, the species and genesis of Nb mineral and Nb-bearing minerals in the Nb–Ta ore deposit are poorly understood [15,19]. On the other hand, the occurrence mode of Nb in the ore rocks and mineral-disseminated properties have not been systematically studied. Moreover, deposit genesis and metallogenic types have been debated to date [16, 19-20]. Initially, we ana-lyzed the compositions of Nb–Ta ore bodies and species of Nb minerals and Nb-bearing minerals in this study. Next, the paragenetic properties of Nb–Ta minerals were analyzed in detail. In addition, the occurrence mode of Nb and the genesis of Nb minerals were discussed. Finally, we introduce the metallogenic type of Yushishan Nb–Ta ore deposit. Our study provides a reference for leptynite-type Nb–Ta ore deposit exploration.”
Point 2: Line93 “Due to undergoing the strong tectonic transformation,” I don’t understand
Response 2: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 125-127, revised version of the manuscript).
“Due to the strong tectonic transformation, the stratum from north to south is a set of amphibolite–leptynite–marble assemblages (Figure 2).”
Point 3: Line96 We don’t use the term ‘stratum’ to describe igneous rocks
Response 3: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 128-129, revised version of the manuscript).
“The main granite body exposed in the mine area is Ordovician diorite granite (Figure 2),”
Point 4: Line99 Reference
Response 4: Thanks for this suggestion. The Reference is [21]. We have revised it.
Point 5: Line 111-112 “A total of 29 ore bodies were ascertained, and the ore bodies were produced along the layers in laminar or plate-like. ” Need a rewrite
Response 5: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 151-153, revised version of the manuscript).
“In total, 29 ore bodies were identified. The ore bodies were produced along the layers in laminar or plate-like organization.”
Point 6: Line 118 etc????
Response 6: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 157-158, revised version of the manuscript).
“The main minerals are quartz, plagioclase, and orthoclase, followed by chlorite, muscovite, biotite, titanite, and magnetite (Figure 3F).”
Point 7: Line 136 Do you mean ‘crushed’
Response 7: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 183-184, revised version of the manuscript).
“The others were crushed and mixed;”
Point 8: Line 140 , “and single mineral composition”. What does mean?
Response 8: Thanks for this suggestion. Due to our inaccurate description, we decided to delete it. The result of the modification is as follows (Line 187-189, revised version of the manuscript).
”At the same time, the mineral composition, structure, disseminated characteristics were tested using the FEI MLA650 mineral automatic analysis system,”
Point 9: Line158 Would you mention the type of the analysis you made to obtain such results
Response 9: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 195-198, revised version of the manuscript).
“In this study, the slice grain size method was used to measure the mineral grain size. Under the microscope, the diameter of grains in the slices was measured, and the per-centage of grains in each group was calculated at 1/4 intervals. More than 300 grains were counted in each slice. The error was ±1 μm.”
Point 10: Line 170-171 “The grain size of fergusonite in the ore is mostly between 5-80 μm. It is au- tomorphic-semi-automorphic or xenomorphic granular with complex embedding styles. Need a rewrite
Response 10: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 235-237, revised version of the manuscript).
“Fergusonite in the ore is euhedral–subhedral or anhedral granular with complex dissemination characteristics. Its grain size is mainly between 5 and 80 μm.”
Point 11: Line 173-175 “(1) The fergusonite crystal is relatively complete and embedded in orthoclase and quartz in microfine automorphic crystal, often crystallizing with zircon at the same time (Figures 4A-C); (2) The automorphic microfine fergusonite crystallize at the same time or contain in magnetite (Figures 4D, 4E);“ Rewrite
Response 11: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 238-243, revised version of the manuscript).
“(1) the fergusonite crystal is relatively completed and disseminated into orthoclase and quartz in euhedral fine-grained crystal, often crystallizing at the same time as zircon (Figure 4A-C); (2) the euhedral fine-grained fergusonite crystallize at the same time as magnetite, or is included in magnetite (Figure 4D, 4E);”
Point 12: Line 194 such as yttrium, Can you justify this abundance of the yttrium in niobite or indicate the ref.
Response 12: We concluded that niobite contains high yttrium based on the results of the energy dispersive spectrometer.
Point 13: Line 206-207 “Ilmenorutile and chlorite in the ore form close groups. The fine-grained rutile, chlorite, and other rare earth minerals aggregate together (Figure 5F).” I don’t understand
Response 13: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 279-281, revised version of the manuscript).
“Ilmenorutile is associated with chlorite in the ore. Fine grained rutile is distributed in aggregates with chlorite and other rare earth minerals in the ore (Figure 5F).”
Point 14: Line 211-215 It is easy to make grammatical mistakes in long sentences.
Response 14: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 287-292, revised version of the manuscript).
“Most Nb–Ta ore minerals are subhedral–anhedral granular aggregates. Part of it is connected with magnetite, ilmenite and zircon. In addition, some of them are wrapped by quartz or feldspar. At the same time, they are also distributed in the intergranular zones and fissures of feldspar and quartz particles in a state of veins and agglomerates. The grain size of independent minerals containing Nb–Ta is in the range of 5-100 μm.”
Point 15: Line 275-287 complete rewrite
Response 15: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 366-378, revised version of the manuscript).
“The main Nb-bearing minerals species of the Yushishan Nb–Ta ore deposit have al-ways been disputed due to two reasons. The first reason is related to differences in analy-sis methods. Jia (2016) found that the main Nb-bearing and Ta-bearing minerals are rutile and monazite contains a small amount of Nb based on observing the thin slices [19]. Chen et al. (2022) found that Nb minerals are mainly columbite, fergusonite, pyrochlore, and Nb-rutile by SEM and EDS [15]. The second reason is the fine grain size of Nb minerals and Nb-bearing minerals in the ore, mostly in the range of 5-80 μm (Table 2). Thus, the naked eye cannot observe Nb minerals and Nb-bearing minerals in the ores (Figure 3C-F). In addition, it is difficult to identify metal minerals such as magnetite under a micropo-lariscope (Figure 3G-J). Regarding the SEM, a large number of measurement points are required in the identification process to obtain representative results due to the small field of view. Therefore, when using a micropolariscope and SEM to identify fine minerals, the results of mineral identification will be incomplete.”
Point 16: Line 310 !!!! You may need to mention the noun of the ore instead of saying niobium minerals contain niobium
Response 16: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 418-420, revised version of the manuscript).
“The results show that Nb in the Yushishan Nb–Ta ore deposit mainly occurs in fergusonite, columbite, polycrase, Nb-rutile, aeschynite, pyrochlore, microlite, and ilmenorutile, with an abundance of about 69.11% (Figure 7, Table 4).”
Point 17: Line 354-358 rewrite and grammatically incorrect.
Response 17: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 472-479, revised version of the manuscript).
“which indicates that the magmatic genesis and hydrothermal genesis of Nb minerals occurred. Later, hydrothermal activities modified part of euhedral fergusonite, polycrase, pyrochlore, and microlite. These are found in the crystals of quartz, feldspar, and magnet-ite or in the mineral interstitials of leptynite (Figure 4A-D, 5D, 6A-6B).”
Point 18: Line 373-376 references or justifiy your argument
Response 18: Thanks for this suggestion. The argument is derived by analyzing the results of scanning electron microscopy. We also describe it in detail in this paragraph.
Point 19: Line 377-393 complete rewrite
Response 19: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 502-522, revised version of the manuscript).
“In summary, Nb minerals can be divided into two types according to mineralization stage. The first type is magmatic mineralization. Euhedral–subhedral granular Nb miner-als occur as inclusions in, or in interstitial positions, among quartz, feldspar, and other minerals, suggesting that minerals are formed simultaneously with these igneous minerals. The main Nb minerals formed are fergusonite, polycrase, pyrochlore, and microlite. The second type is hydrothermal mineralization. Different Nb minerals occur in ore fissures in a state of irregular vein and agglomerated aggregates. These Nb minerals are closely associated with metamorphic minerals such as chlorite, albite, and secondary quartz. The direct metasomatic origin among different Nb minerals can be seen locally, including columbite, fergusonite (anhedral granular), Nb-rutile, and aeschynite. Due to the host-rocks of the magmatic mineralization stage being affected by regional tectonic–thermal events, rare metal elements such as Nb were mobilized and migrated in the short distance migration by later hydrothermal fluids and enriched Nb–Ta ore deposits in the favorable host-rock, such as mineral fissures, gaps, and edges of primary Nb minerals, etc.”
Point 20: Line 401-425 complete rewrite
Response 20: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 530-575, revised version of the manuscript).
“(1) The block of the western part of Central Qilian rifted during the Neoproterozoic Era (834-790 Ma). The Nb-rich intermediate-felsic magmatic rocks were formed in the Yushishan.
The Northwestern China paleo-continent responded to subsequent rifting events (850-700 Ma) [32,36,37] after the converge of the Rodinia supercontinent (1000-900 Ma) [28]. The tectonic location of the study area is in the western part of the Central Qilian Block. The north of the study area is adjacent to the eastern part of the Altun Tagh Block and the south is adjacent to the northern part of the northern margin of the Qaidam Block (Figure 1). These three tectonic units were in the process of continental rifting during the middle and late Neoproterozoic Era (834-790 Ma) (Figure 8A), corresponding to the rifting stage of the Rodinia supercontinent [30,32,38-43]. The protolith of the hosting leptynite of the Yushishan Nb–Ta ore deposit was formed in the middle–late Neoproterozoic Era. Its petrogenic age is 834-790 Ma [15-16,22], which corresponds to the tectonic setting of con-tinental rifting in the region. Chen et al. (2022) showed that the protolith of leptynite were intermediate-felsic magmatic rocks that erupted in an intracontinental rift environment [15-16]. The upwelling of the lithosphere and asthenosphere triggered intracontinental rifting and led to volcanic eruption (Figure 8B). Thus, the intermediate-felsic Nb–Ta ore-forming protolith rich in rare metal elements such as Nb were formed and intruded into the carbonatite wall rocks (Figure 8C). In the ore-forming protolith, there are Nb min-erals such as fergusonite, polycrase, pyrochlore, and microlite, and rare metal mineral such as zircon are formed (Figure 8D). The initial enrichment of Nb, Ta and other rare metals occurred during this stage in the Yushishan deposit.
(2) The Quanji Block in the northern boundary of Qaidam Basin, the western part of the Central Qilian Block, and the northern boundary of Altun Tagh Block subducted and converged during the Caledonian period (510-450 Ma). This caused strong tecton-ic–magmatic thermal events, which led to the activation and enrichment of Nb and other rare metals in the ore host- rocks in the western part of the Central Qilian. This was the second stage of Nb–Ta mineralization.
The Quanji Block in the northern boundary of Qaidam Basin and the western part of the Central Qilian Block, as well as the northern boundary of Altun Tagh Block located in the plate convergence and subduction tectonic environment at 510-450 Ma [29-31,41,44-47]. During this period, the Northern Altun Tagh ocean and the Southern Qilian ocean subducted southward [29,41].”
Point 21: Line 441-443, 445-449 Hydrothermal alteration is leading to what exactly?? I don’t understand
Response 21: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 588-598, revised version of the manuscript).
“During 490-455 Ma, the intermediate-felsic magmatic rocks and carbonatite were metamorphosed to leptynite and marble in the Yushishan area, respectively. Hydrothermal alteration phenomena such as chloritization, albitization, silicification, and potassium alteration occurred in the leptynite. The hydrothermal alterations activated rare metal elements such as Nb and promoted short distance migration in the ore-forming host-rocks (niobium-rich magmatic rocks). Eventually, Nb–Ta ore bodies formed in the favorable host-rocks (Figure 8G). However, there was no Nb mineralization in the roof and base plate marbles.”
Point 22: Line 463-470 Grammatically incorrect
Response 22: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 614-624, revised version of the manuscript).
“Hydrothermal Nb-bearing minerals (columbite, fergusonite, aeschynite, and Nb-rutile) contributed approximately 26.67%-49.13% Nb to the Nb–Ta ore deposit, including mag-matic fergusonite. The contribution of Neoproterozoic (834-790 Ma) magmatism and Cal-edonian (490-455 Ma) hydrothermal effect to leptynite type Nb–Ta ore deposits is ap-proximately the same. Therefore, the leptynite type Nb–Ta ore deposit in the study area is a new mixed type of Nb–Ta ore deposit.”
Point 23: Line 478-519 complete rewrite
Response 23: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 633-664, revised version of the manuscript).
“There are three modes of occurrence of Nb in the Yushishan Nb–Ta ore deposit: (1) Nb occurs in minerals such as fergusonite, columbite, polycrase, and Nb-rutile, account-ing for 69.11% of the total Nb in the ore; (2) microscopic inclusions of Nb minerals dis-persed in titanomagnetite–magnetite hematite, which account for 17.90% of the total Nb in the ore; (3) microscopic inclusions of Nb minerals dispersed in gangue, accounting for 13.00% of the total Nb in the ore.
The main Nb minerals in the Yushishan Nb–Ta ore deposit are fergusonite, colum-bite, and polycrase. They contribute 52.51% Nb to the ore. Among them, Nb is mostly hosted in fergusonite, reaching 22.46% Nb. The total Nb percentage of Nb-rutile, aeschyn-ite, pyrochlore, microlite, and ilmenorutile is less than 10%. These minerals contribute 16.59% Nb to the ore.
Nb minerals in leptynite ores have two genetic types, which are formed in two stages impacted by the tectonic activities. The first stage (834-790 Ma) is magmatic. Nb minerals are euhedral–subhedral particles distributed in quartz, feldspar, and other primary min-eral crystals or crystal gaps. Nb minerals, including euhedral–subhedral fergusonite, polycrase, pyrochlore, and microlite, are formed together with the primary minerals. The second stage (510-450 Ma) is hydrothermal. Different Nb minerals in a state of irregular vein and agglomerated aggregates filled in the ore and primary mineral fissures. They are closely associated with metamorphic minerals such as chlorite, albite, and secondary quartz. At the same time, direct metasomatism among different Nb minerals can be seen locally, including columbite, anhedral granular fergusonite, Nb-rutile, and aeschynite. The two mineralization stages contributed roughly equal Nb to the Yushishan Nb–Ta ore deposit.”
We look forward to hearing from you in due time regarding our submission and to respond to any further questions and comments you may have. Thanks for your time.
Best wishes
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The authors have made considerable changes to the manuscript and the quality has sharply improved.
I suggest some more changes before acceptance, as detailed below.
One concern is the large amount of citations of papers in Chinese, which give limited access to an international audience. I suggest a few references to papers published in well-known journals. Please also consider the entirety of the references.
Please also check the validity of the geological epochs used.
Line 15. Another, instead of the other.
Line 16. The meaning of isomorphism is unclear. Does it mean that Nb is present as a minor element in Ti-magnetite-maghemite?
Line 44. Repetition, delete “according to the hosting rocks”.
Line 64 Several of these references are in Chinese, which makes them less accessible to an international audience. There are many English language papers that can be cited. For instance, add Agangi et al., 2014 Lithos; Vasyukova and William-Jones, 2014 to the list of references.
Line 83 (and elsewhere). The ages (periods) mentioned seem to refer to local geology (e.g., Jixian, etc.). It would be better to make sure that the periods mentioned correspond to the international geochronological scale.
Lines 270 and following. Please consider the significant number of decimals in these percentages. Two significant figures are used in the following paragraph.
Line 230. The meaning of “the phenomena of filling effect” is unclear. Re-phrase.
Fig1. Should have colours to indicate the units, in addition to the labels.
Table 1 contains mineral abundance estimated from MLA. Were they converted to weight per cent, or should they be volume per cent?
Fig 6.d contains a note that should be removed and added to the caption.
Author Response
Dear reviewer,
Thank you very much for your comments and suggestions. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewer’s comments are as follows.
Point 1: One concern is the large amount of citations of papers in Chinese, which give limited access to an international audience. I suggest a few references to papers published in well-known journals. Please also consider the entirety of the references.
Response 1: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. We added some papers published in well-known journals to the list of references and checked all references in the manuscript. Please check it.
Point 2: Please also check the validity of the geological epochs used.
Response 2: Thanks for this suggestion. We have made checked and modified according to the reviewer's comments. Please check it.
Point 3: Line 15. Another, instead of the other.
Response 3: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 4: Line 16. The meaning of isomorphism is unclear. Does it mean that Nb is present as a minor element in Ti-magnetite-maghemite?
Response 4: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 16, revised version of the manuscript).
“The another 17.90% Nb as a minor element was dispersed in titanium magnetite-maghemite,”
Point 5: Line 44. Repetition, delete “according to the hosting rocks”.
Response 5: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 6: Line 64 Several of these references are in Chinese, which makes them less accessible to an international audience. There are many English language papers that can be cited. For instance, add Agangi et al., 2014 Lithos; Vasyukova and William-Jones, 2014 to the list of references.
Response 6: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. We added Agangi et al., 2014 Lithos; Vasyukova and William-Jones, 2014 to the list of references. Please check it.
Point 7: Line 83 (and elsewhere). The ages (periods) mentioned seem to refer to local geology (e.g., Jixian, etc.). It would be better to make sure that the periods mentioned correspond to the international geochronological scale.
Response 7: Thanks for this suggestion. We have made corrections based on the international geochronological scale. Please check it.
Point 8: Lines 170 and following. Please consider the significant number of decimals in these percentages. Two significant figures are used in the following paragraph.
Response 8: Thanks for this suggestion. We have checked the significant number of decimals in these percentages in the paper. All the samples weigh approximately 5035 kg in our study. Each sample weighed approximately 560 kg on average. We sorted all minerals from the rock samples. When calculating the mineral percentages, the results reached four decimal digits for some minerals with particularly low contents. So, we use four significant number of decimals for mineral content. The two significant figures in the following paragraph represent the grain size distribution of mineral (Table 2). Please check it.
Point 9: Line 230. The meaning of “the phenomena of filling effect” is unclear. Re-phrase.
Response 9: Thanks for this suggestion. We have made corrections based on the reviewer’s comment and the results are as follows (Line 233, revised version of the manuscript).
“The phenomena of filling-metasomatism of the fine magnetites can be seen around the edge of mineral crystals (Figure 6F).”
Point 10: Fig1. Should have colours to indicate the units, in addition to the labels.
Response 10: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
Point 11: Table 1 contains mineral abundance estimated from MLA. Were they converted to weight percent, or should they be volume per cent?
Response 11: They converted to weight percent.
Point 12: Fig 6.d contains a note that should be removed and added to the caption.
Response 12: Thanks for this suggestion. We have made corrections based on the reviewer’s comment. Please check it.
We look forward to hearing from you in due time regarding our submission and to respond to any further questions and comments you may have. Thanks for your time.
Best wishes,
Reviewer 4 Report
Dear authors,
The decision to adopt the present draft was taken after extensive check of the text. We are seeing a great difference between this version and the first one; clear sentences and significant increase of the quality of your paper.
Best regards,
Author Response
Dear reviewer,
Thank you very much for your comments and suggestions. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches.
Best wishes,
