The Evolution of Permian Source-to-Sink Systems and Tectonics Implications in the NW Junggar Basin, China: Evidence from Detrital Zircon Geochronology

Round 1

Reviewer 1 Report

Line-32： Add necessary references to support each sentence.

Introduction: Present the current and previous studies, not only list the number.

Focus the scientific issues in the Introduction. Tell the authors why you carried out the researches.

Add significance of your research.

All in all, the introduction should be re-organized.

Line 62: According to magmatism and stratigraphic distribution, list the characteristics of each part.

Line 82-96: Add references.

Line 131: “principally intermediate-felsic and intermediate-mafic volcanic clasts” Add photos and evidence to support your view.

Line 164: The authors suggest “The results indicated that the zircons were predominate of magmatic origin.”, thus how about the remaining ones? Not all the zircons belongs to magmatic ones?

Add the REE and other elements as a line of evidence to verify the conclusion from Th/U.

Line 248: Parent Rock …Provenances

Line 283: been discovered in the WJ. Add references.

Line 368-369: It should be noted that only one sample of the Xiazijie Formation was analyzed here, so the uncertainty did exist. If this sample is not certain, how can you ensure others?

zircon-tourmaline-rutile (ZTR) index is not first proposed by you, thus a detailed introduction and references should be added.

5.3. Source-to-sink system Division and Provenance System Evolution is a little confused. Present as a new form, such as line 1, 2,…or others.

Condense your conclusions. Some are not your conclusions, just description.

Throughout the whole text, we haven’t got the advances of your research instead of others. Focus on the scientific issues of your research.

Take care of the references and should not be ignored after the sentences that are not proposed by you.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript titled "The evolution of Permian source-to-sink systems and tectonics ..." by Xingyu Chen and others is intended to determine the provenance and tectonic history of Permian sedimentary rocks in the Junggar Basin of China using zircon U-Pb age dating methods.  The authors collected 26 rock samples from five different Permian formations in the Mahu-Zhongguai area and determined the various U-Pb ages of several zircons in each of the samples.  The radiometric data was then compared with published age data from potential source areas. Because there is no Permian outcrop on the northwestern margin, all of the 26 samples were collected from drilling cores. 

The research that was accomplished and the conclusions reached is the result of a considerable effort and are potentially useful and interesting, although some changes need to be made to make the manuscript less confusing and readable.  The large number of formations and areas involved and the over use of abbreviations make it difficult to follow, requiring several careful re-reads on my part before any clarity was established. Some specific suggestions follow:

Abstract – The abstract is absolutely a mess.  It will need to be completely re-written with potential readers in mind.  As is, there is no information provided. Starting with the first sentence, the word "of" should be replaced with "it is". The second sentence is a problem because lithology was largely ignored. Almost all interpretations were based on detrital zircon ages. Then several location names are introduced without putting them in any context in a jumble of confusion. Each name needs to be defined in the context of the Junggar Basin to make any sense. For example, what is the Mahu Sag and why is the Wuerhe Formation important?

Line 79 – The font size of the figures is way too small. 

Lines 90-96 – A more complete description of the Permain formations needs to be made. Are none of the sandstones marine?  They appear to be what was once described deltaic subgreywacke based on their poor sorting and feldspar and volcanoclastic lithic fragment content. It would be helpful if the mineral content and lithic fragment content was provided on a percentage basis for a few typical samples. What is the evidence that they are alluvial fan and fan delta and littoral-shallow lacustrine facies. You must provide evidence. And how did all that dolomite get there? Is it not marine? What is the fossil evidence if any?

Line 129 – "sub-rounded" not "sun rounded"

Line 144 – How was it determined how many of the zircons were sourced from older igneous intrusions verses underlying volcanic rocks including all the andesite, basalt, rhyolite, and tuff of Figure 2 and elsewhere?

Table 2 – "Component content" must be explained in the table caption. What are P, C2 and C1?

Line 191 – Were the ophiolitic mélange belts age dated using zircons? It is typically very difficult to extract zircons from ophiolite.

Lines 317-319 – Again, it is rare to find zircons in ophiolite so their absence in the sedimentary rocks may be meaningless.

Line 376 – Heavy mineral data can be very useful in correlating sediments with specific granitic source rock.  It seems disappointing that after collecting so many heavy mineral samples no such correlations were attempted. The authors have several different granites to choose from, each with their own characteristic heavy mineral content.

Line 457 – This points out the tremendous difficulty in relying so heavily on radiometric data in determining the provenance of sedimentary rocks particularly in the absence of any evidence of a paleo-drainage system other than some rather weak ZTR index data.

Lines 580-581 – Please remind the reader of the evidence for an adjacent mountain source.

Lines 626-627 - Please remind the reader of the evidence for an adjacent mountain source.

Lines 670-675 and 682-685 - It would be very helpful if a cross-section was provided illustrating your proposed overthrust nappe and thrust-nappe system and the accretionary orogeny on the SW margin of the CAOB.  This would be particularly important since none of the Permian is exposed to the surface on your maps making it difficult to visualize.

Additional note – Are there any applications of this research to the oil potential of the Permian rocks?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

 

作者做了认真的修改  

The The authors made a serious revision.

Reviewer 2 Report

The revised manuscript is a huge improvement over the original draft and, in my opinion, is ready for publication. I am particularly happy to see an abstract that is clear and makes good sense.