Geochronology and Geochemistry of Granitic Pegmatites from Tashidaban Li Deposit in the Central Altun Tagh, Northwest China
, Xuehai Wang 1,2,3, Zhaoxia Liao 1,2,3, Lei Niu 6, Jianzhong Chen 4, Xingzhong Liu 4 and Xingwang Xu 1,2,3,*
Round 1
Reviewer 1 Report
Comments and Suggestions for Authorsthis manuscript present the geological characteristics of the Tashidaban Li deposit and constrain the petrogenesis and mineralization age of the Li granitic pegmatites by columbite-tantalite group minerals (CGMs) and zircon U-Pb dating, and discuss the tectonic setting of the Tashidaban Li deposit.
The following comments and suggestions are for your reference：
1. The yellow font in Figure 3 is inconspicuous, so it is recommended to change it to another color.
2. Methodological descriptions of whole rock analysis are lacking in “4. Sample selection and Analytical methods”
3. It is recommended to add a sample profile table in “4. Sample selection and Analytical methods”
4. Line 197, Figure 4a does not show black for CGM.
5. Line 200, “varying from 449-445 Ma”, The figures may be wrong
6. The analysis of zircon has only 5 points, which is a little less, is only 5 analyzed, or only 5 data can be used?
7. The CL image of the zircon in Figure 4 is too black to see the internal structure clearly, can you change it to the BSE image?
8. Line257, is that common Pb incompatible in CGM?
9. 6.2.1 discusses the genetic types of granite, not origin
10. Since it is a deposit, “3. Geology of the Tashidaban Li deposit” should introduce the grade and scale of the deposit
Author Response
Thank you for the meticulous suggestions provided by the reviewer. We have responded accordingly to the respective suggestions.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe article "Geochronology and Geochemistry of granitic pegmatites from Tashidaban Li deposit in the Central Altun Tagh, Northwest China" was written at a high professional level.
The research results expand our knowledge about the genesis of rare metal pegmatites, the source of their formation and the tectonic conditions for the formation of large deposits of rare metal pegmatites.
In the discussion it is necessary to add information about the deposits of the world that were formed in a similar tectonic environment.
The article “Geochronology and Geochemistry of granitic pegmatites from Tashidaban Li deposit in the Central Altun Tagh, Northwest China “contains the results of the study of three types of rare metal pegmatites:
1. tourmaline pegmatite,
2. elbaite pegmatite
3. spodumene pegmatite
from Tashidaban Li deposit in the Central Altun Tagh, Northwest China.
According to the authors of the article: “The Central Altun orogenic system is a product of the amalgamation of multiple microcontinental blocks and island arcs. This complex system originated from subduction-accretion-collision processes within the Proto-Tethys Ocean during the Early Paleozoic era. Recent research has unveiled the presence of several Li-Be granitic pegmatite deposits in the Central Altun Block, including the Tashidaban Li deposit “
Geochemical results indicate that the Tashidaban Li granitic pegmatites may have resulted from the highly crystallized differentiation of the Kumudaban pluton.
The article increases our knowledge about the genesis of rare metal pegmatites and the tectonic conditions of their formation
The article may be recommended for publication with minor changes
Lines 38-40
“Rare metal granitic pegmatites, enriched in incompatible elements such as high field strength and large ion lithophile elements, constitute vital sources of lithium metal”
Large ion lithophile elements (LILE) – ‘these are Cs, Rb, K, Ba, Sr, often Pb2+, Tl+, Eu2+. But Rare metal granitic pegmatites are depleted in Ba and Sr. Therefore, this proposal requires clarification.
Lines 124-125
“There are forty-two pegmatite dikes hosted in Tashidaban Li deposit, eleven of which are Li mineralized.”
Do other dikes have mineralization or are they barren?
What is the relationship between these dikes?
Lines 125-126
What is the relationship between tourmaline pegmatite, elbaite pegmatite and spodumene pegmatite?
What dikes are included in the deposit?
Is it possible to separate the deposit-Li and the pegmatite field?
Lines 158-160
“The whole rock geochemical samples are from the vicinity area of the Kumdaban pluton, the Tamuqie Li deposit, and the Tashidaban Li deposit area.”
Write for what purpose these samples were taken
Lines 237-238
“The fine-grained aplite sample of the spodumene pegmatite (448 Ma) in the Tamuqie Li depositе…”
There is geochemistry, but there is no geology for the Tamuqie Li depositе
What pegmatites are there in the Tamuqie Li deposit?
Comments for author File: Comments.pdf
Author Response
Thank you for the meticulous suggestions provided by the reviewer. We have responded accordingly to the respective suggestions.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript is relevant for the field and represents new data about geochronology and geochemistry of newly discovered Tashidaban Li deposit at the northern margin of the Central Altun Block, Northwest China. Li-bearing granitic pegmatites, mainly spodumene and elbaite types are hosted in the Tashidaban Li-deposit, intruding two-mica shist and marble that are part of the Muzisayi Formation of the Tashidaban Group. The geochronology is based on U-Pb daing of pegmatite accessory zircon and minerals from columbite-tantalite group. The U-Pb dating indicate a mineralization age of 450.2+- 2.4 Ma for the pegmatites, with suggested superimposition of a later (418-412 Ma) magmatic event.
The whole-rock geochemistry reveals that the nearest Kumudaban pluton belongs to the S-type calc-alkaline granite and the Tashidaban Li granitic pegmatites may originated from the highly crystallization differentiation of this Kumudaban pluton.
The abstract is informative and complete.
The cited references are relevant I suggest.
The manuscript is well structured, although I suggest complementation of the methodology chapter with a description of SEM and CL (optical-CL or SEM-CL) methodology, which are obviously used but not included and described.
Figure 1. must be technically improved regarding quality, it is not well visible and readable. The enlargement, especially of the text of the legend is recommended.
Figure 3. The mineral abbreviations on the pictures are not visible. There is missing information about the zones of the pegmatites, not all minerals are labeled. The photograph information in the fig. caption doesn't correspond to the information in the text descriptions. There are Inconsistencies concerning the numbers of the samples. A detailed descriptions of the photomicrographs in fig. captions in terms of the mineral relationship is recommended. The studied accessory minerals (zircon and Col-tan) should be described and illustrated better with optical microscopic observation, SEM and CL images, because of their specific properties, internal structure, inhomogeneity and zoning. The presence of inherited cores in the zircon is important feature when choosing places for dating and interpretation of the data. According to the scale of the photomicrographs the grains of the studied minerals are sufficiently large for this visualisation. It would be better if the size of the pictures is bigger.
Part of the results could be illustrated better with supplemet photomicrographs, SEM and CL images. As it was mentioned above better description of the studied accessory minerals (that are the main topic of this study) in terms of mineral association, textural properties, inhomogeneity etc. is recommended. Presence of metamictization or recrystallization, oscillatory zoning, indications for hydrothermal alteration, genetic origin should be discussed. EPMA and trace element data are highly recommended for the improvement of the manuscript quality.
Conclusions can be improved if they are supported by additional arguments.
See attached file for additional remarks.
Comments for author File: Comments.pdf
Minor editing of English language required
Author Response
Thank you for the meticulous suggestions and making modifications to the English expression provided by the reviewer. We have made substantial revisions this time, and we have also addressed the issues in the PDF document.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsMy comments can be found in the attached pdf file.
Comments for author File: Comments.pdf
Moderate English changes required
Author Response
We find the critique valuable and helpful for revising our manuscript as well as for emphasizing the broader significance of this research topic. Please find the detailed responses below and the corresponding revisions changes in the re-submitted files
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThank you for the substantial revisions. The paper is valuable and has new and interesting data.
Author Response
Please see the attachment. Thank you for your constructive feedback.
Author Response File: Author Response.pdf
