Identification of the Sedimentary Sources and Origin of Uranium for Zhiluo Formation of the Tarangaole U Deposit, Northeastern Ordos Basin

Round 1

Reviewer 1 Report

This paper carried out whole-rock geochemistry, heavy minerals composition and in-situ U-Pb dating of detrital zircons for Zhiluo Formation of the Tarangaole deposits.

Material has high potential and interest for several reasons. 1. These deposits located in the northeastern margin of the Ordos Basin, constitutes uranium resource base in northern China. 2. The authors of the article use original unique material, mainly from boreholes, which has great potential for studying deposits of this type. 3. The authors use an integrated approach using modern methods.

However, the manuscript is raw and needs to be significantly improved to make it readable for an international audience.

Main comments:

1. Methods are not used carefully.

            а) The authors, based on the whole chemical composition of sandstones, find out the conditions of single sedimentary sources (lines 201-205). But the zircons show that there are at least two sources, Permian and Proterozoic. One is igneous, the other is metamorphic. Moreover, to determine the source environment Pearce et al., 1977 diagram (fig. 8) was used, which has been developed for volcanic rocks.

b) Fig. 4, which provides data on the heavy fraction, is not attached to manuscript, although the authors often refer to it. There is also confusion in the text about the heavy fraction:

lines 170-171: «The main heavy minerals in the Zhiluo Formation sandstones are ilmenite, green zoisite, garnet (>40%), followed by zircon, pyrite, apatite, hematite, etc. (within 10%)».

lines 221-222: « The main heavy minerals within the sandstones of the Zhiluo Formation are ilmenite, garnet, chlorpyrite, zircon, pyrite, apatite and hematite».

Where is zoisite, what chlorpyrite is?

c) There are no microscopic descriptions of sandstones. For this kind article, this is necessary. It is also good to determine the composition of the clastic part in thin sections. For macroscopic description, it would be good to add a description of the textural features and the direction of paleocurrents.

d) Statistical data on the ages of zircons is not very accurately described. For example, line 192 says that there are 3 peaks in the rocks, but on the graph in Fig. 7 d, f, h- peaks are much larger, for some reason they are ignored in the description. It is possible to describe the population interval and highlight the peaks in it, and then use the intervals.

In Figure 9, histograms are constructed for a large amount of data, although the world practice is more accurate for statistics to construct probability curves PDP or KDE. It would be good to normalize all the probability curves.

e) By authors Th/U values for “older zircons” is 0.1-0.4 (lines 183) although on the graph fig. 6 they are up to 1. Yes, unlike from“young” grains there are values below 0.4, but grains with such values do not predominate. Conclusions need to be made more carefully.

f) It is written that 60 samples were collected and analyzed (lines 101-102), although it is described in summary not more 30 samples.

2. Regional material.

Overall well written. There is a very lack of a section or column that would show the relationship of the Jurassic rocks older and younger rocks.

3. Not very scientific sounding.

a) Several times (lines 178, 276) «CL images» used as some main characteristics, phrase like “According to CL images…..suggested that the sources of sandstones…”. Image can show grain's shape, zoning etc, which can be used to reconstruct the source, but not image itself.

b) Zircon grains are described as young (line 180) and ancient (line 182). Ancient and young relative to what?

c) Lines 212-219 – the text contains general information that can simply be referred to and not described in so much detail. data from table 3 does not correspond to the text from lines 212-219.

d) Some misused terms are glaring:

191, 254 harmonic (lines 191, 254)– age, line – better to change to Concordia.

zircon particles (line 178) – better to change grain.

discriminant map (line 199) –plot, diagramВыводы:

3. Discussion and conclusion

a) The regional context of the sources is poorly described (lines 247-261). There are no ages of the sources, very little geological description for it. For comparison, comparative histogram of zircon ages is given (fig. 9), but it does not show 100% similarity for sources. For example, the main source Wolf Mountain has a clear peak between 500-1000 Ma, for Eastern Alashan there are a lot of Paleozoic grains and many minor signal for 500-1500 Ma grains. There is no explanation for this difference

            b) As sources in conclusions and abstract uses terms like: «…the eastern part of the Ula-Daqing and Wolf mountains». It is difficult for a reader who does knows regional geology to understand what is this. It is necessary to briefly reveal what it is rock composition, nature and tectonic setting for this structure.

3. Paleozoic granites (lines 272-275) are described as the main source of U. The reason is the high uranium values in granites. However, it is not clear in what state of aggregation is uranium found in granite?, how uranium were transported (solution, solid phase) and why Uranium deposited in the rocks of the Zhiluo Formation.

 The material can be worked with and the article has the potential to be published. The article must be revised and submitted again for review.

English is understandable, at a normal level.

Check the terms more carefully, such as concordia, diagram, etc.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Editor, Dear Authors

Thank you very much for the opportunity to review the manuscript “Identification the Sedimentary Sources and Origin of Uranium for Zhiluo Formation of the Tarangaole U Deposit, Northeastern Ordos Basin” from Guang-yao Li and others. The authors use whole rock geochemical data, detrital zircon U-Pb LA-ICP-MS data, and heavy mineral aseemblage qunatifications to imply on the source of the sediment and the U in the Zhilou Formation of the Tarangaole U Deposit.

This manuscript is well structured, and the data appear to be reliable. But the text should be improved.  One issue is English language, but the other is that some sentences are not very precise. I marked the sentences which I did not understand in the text. These need to be reformulated. Many other words or phrases could be substituted by more common descriptions.  Nevertheless, the overall story is well understandable and I recommend minor revision, mainly to improve some figures and the quality of the text.

Detailed comments to the text and figures are given in den attached pdf.

Comments for author File: Comments.pdf

There are some phrases that have obviously been translated word-by-word from another language. But if there are specific and scientific phrases, these should be used, e.g.:

harmonic diagrams - age spectra

growth ring and rhythmic structure - oscillatory zoning

self shaped - euhedral

Furthermore, there are some minor problems with singular vs. plural words and some sentences sound a bit strange and would profit from being rearranged. But since I am not a native speaker, I do not feel able to do this re-arrangement. I think the authors have to find a native speaker for help with the language.

Author Response

Dear Reviewer:

Thank you for your decision and constructive comments on our manuscript. We have carefully considered your suggestion and modified the manuscript according to your comments. Revision notes, point-to-point, are given in the comments of the attached pdf.

Author Response File: Author Response.pdf

Reviewer 3 Report

I have quite some problems with the manuscript.

Most problematic is, that in my opinion the reported data does not allow to conclude what the title seems to indicate. All that possibly can be derived as a conclusion from the manuscript is that the sandstones of the Zhiluo Formation probably contain detrital minerals which can be derived from the northerly plutonic rocks and the intervening metamorphics. That the plutonic rocks of the Wolf Mountain, etc. are U-rich is correct, but no further evidence is provide in the form of potential U-carries, erosional and depositional and diagenetic processes. In short, the data does not readily support the conclusions of the manuscript.

There are additional short comings in the data reduction and presentation of the zircon U-Pb ages, the data presentation as such and in the figures and data table presentation.

The English needs are very thorough revision by a native English speaker.

I have addressed a lot of issues directly in the manuscript to stress my poitns.

Comments for author File: Comments.pdf

The English needs are very thorough revision by a native English speaker.

Author Response

Dear Reviewer:

Thank you for your decision and constructive comments on our manuscript. We have carefully considered your suggestion and modified the manuscript according to your comments. Revision notes, point-to-point, are given in the comments in the attached PDF.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors did not make all the edits and worked only partially. The answers contain inaccuracies.

1. For the petrography of sandstones (Line 99-104; Line 76-79).  It is necessary to give the names of sandstones -  arenit, grauwack etc.

2. Fig.9 (now Fig.8) has not been modified, there is no PDP curve. The old remark remains relevant:

«In Figure 9, histograms are constructed for a large amount of data, although the world practice is more accurate for statistics to construct probability curves PDP or KDE. It would be good to normalize all the probability curves»

3. Zircon grains are described as young and ancient (line 188). Better to use category age (Paleozoic grains; 300-450 Ma zircons), not young and old category.

4. Fig. 4 – it is not convenient to look at the symbols.

5. All comments related to the discussion and conclusion have been partially made. The response contains a link to lines 340-348; 340-348 (double); 381-386, but after line 336 there is a references, there is no text.

In general, the text can be accepted for publication.

English has been improved and is acceptable and understandable.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

The revised manuscript is in parts significantly improved and I see that some of my original comments have been taken into account.

Other comments the authors have decided to not address and this without any reasoning, i.e. replies to my comments are largely missing. This is true for comments throughout the manuscript, but especially important for the content of Fig. 5 and Fig. 6. Especially the calculation and reporting of simple density functions taken from 'Isoplot' must be changed, as I have discussed and asked for in the original review. Otherwise, the authors have to comment on why they choose to maintain the outdated and mathematically wrong statistical approach.

Minor editing of English language required

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

I am pleased to see that my suggestions and corrections have been mostly accepted and worked into thr revised manuscript. I thank the authors for the very accurate revision of the original manuscript.

The English is appropriate and only needs one last checking for typos.

Author Response

Thank you very much for your significant review to improve this paper.  We also appreciate your warm encouragement and expect to take academic discussion with you in future.