Late Cretaceous Activity Record of the Guangsan Fault—Insights from Zircon U-Pb and Apatite Fission-Track Thermochronology
, Weihao Chen 1, Cleber Soares 4, Weisheng Hou 1,*, Zilong Li 1, Yangshijia Li 1, Rongli Huang 1 and Heping Zou 1Round 1
Reviewer 1 Report
This is a good paper but there is the need for improvement of the English. I have made suggestions in this regard
Comments for author File: 
Comments.pdf
Author Response
We very appreciate the reviewer's suggestions and they are very helpful for improving the paper. The attachment is the revision and detailed responds for each question or comment. Anyway, many thanks. Hope the revision is better than before.
Author Response File: Author Response.pdf
Reviewer 2 Report
To the authors...
Please see the comments typed into the pdf of your original paper. I am sorry if the review comments seem a bit harsh at times - but I sincerely struggled to understand what was presented due to the English. I know it is asking a great deal, but in the future it would help reviewers a great deal by having papers first revised for English presentation before submitting for formal scientific review. Even with English as my first language, I still send out all papers I am writing to have the English text revised, before submitting for review. Just a thought.
The new ZrnUPb and AFT data are excellent. However, the presentation of these data is either: 1) too expansive (ZrnUPb) and can be significantly reduced (remove all the unnecessary images); or 2) insufficient (AFT) making a detailed evaluation of the AFT results/interpretation difficult. In my opinion, the interpretations of the results provided do not seem to be supported by the data. I have provided an alternative interpretation for your consideration - but acknowledge that this interpretation is purely that of a knowledgeable outsider.
Details and interpretation of the data would be greatly assisted by bringing Cleber on as a co-author, and having him assist with a more detailed interpretation based on his expertise and understanding of AFT, not the results of dumping data into some program and accepting the output.
Comments for author File: Comments.pdf
Author Response
We very appreciate the reviewer's suggestions and they are very helpful for improving the paper. The attachment is the revision and detailed response for each question or comment. Anyway, many thanks. Hope the revision is better than before.
Author Response File: Author Response.pdf
Reviewer 3 Report
Review – Minerals-1812405
Age determination of fault activity is a challenging point in geological research. The Guangsan Fault is chosen as example and a combination of zircon U-Pb and apatite fission-track geochronology is applied on six samples. Thermal history reconstruction is provided based on two samples, each one from the fault breccia and surrounding rhyolitic rock, respectively, with similar results.
Our main concerns are:
(1) Is the manuscript suited for Minerals? Although it publishes geochronological work, it is likely of a methodological nature and not a simple geological application.
(2) Seven authors for six samples seems a bit excessive, given that the U/Pb work was done in Wuhan and the AFT work by Cleber Soares. We must assume that this was paid work since no-one from there is co-author.
(3) This raises the question: who did what at SYSU? The list at the end is a smokescreen that says nothing about the contributions of the authors at SYSU.
(4) There are much earlier and more comprehensive AFT and ZFT fault studies as well as a number of more general publications, e.g. T. Tagami (2019): Application of Fission-Track Thermochronology to Understand Fault Zones.
(5) This manuscript gives the impression of an attempt to get as many papers published with as few data as possible, inflating their significance and the self-references to rather questionable papers by some authors.
(6) Although the (purchased) data seem to be of good quality, and their interpretation suggests a fair understanding of the methods, the whole effort is, in our opinion, far too insubstantial to be worth publishing. The approach is not new, superficial and the significance of the Guangsan fault has not been demonstrated in the introduction.
(7) There is no comprehensible source, which explains how the Low-T Thermo program works. On the one hand, it seems to be a development of an older program, whose description was submitted to Geoscience Frontiers, but rejected. On the other hand, it seems to be a clone of HeFTy, or HeFTy under a different name. In the latter case, the intellectual ownership of the program should be reconsidered. This must be clear.
(8) The conclusions are, as far as we can tell, reasonable although they likely go too far, where the Dpar values and the modelling results are concerned. That is however not uncommon. It is less certain that the proposed conclusion is the only possible solution.
(9) The figures should be properly arranged (moving part of them to a supplement and deleting others) and the references should be more representative in particular where the dating of fault movements is concerned.
(10) The manuscript requires some improvement in language, style and the figures have to be improved. We therefore add an annotated PDF, which addresses most of these issues.
Further specific comments:
(1) The introduction is too brief to illustrate the current study progress of fault geochronology and mostly refers to trivial literature. Additionally, the chosen Guangsan fault as an example is not well presented. D’Alessio et al. (2003): No frictional heat along the San Gabriel fault, California: Evidence from fission-track thermochronology show that fault related friction is not always certain to reset the AFT system, only if specific physical conditions are present. Are these conditions given at the Guangsan fault?
(2) There is no information about a kinematic study of the fault, e.g. derived from a thin section analysis (pseudotachylytes?) or texture analysis. These make it difficult to interpret the age results. Do the slightly younger AFT ages really represent a reset by fault activity?
(3) Heat generation by fault friction is very localized in a cm to sub-meter range. The authors should document whether the samples show any sign of fault related overprint, instead of hand specimens and drill cores.
(4) Judging from Figure 1, the profile starts at the fault and continues about 1 km southward. Why is the profile not continued northward? The fault seems to be mainly dominated by sinistral shear sense, but maybe there is also a vertical component present?
(5) The methodology to determine U content by LA-ICP-MS for AFT geochronology leaves uncertainties, due to influences by heterogeneous distribution of actinides, despite some useful attempts. Why the authors set the spot size to be 30 and 40 μm and why not use a consistent spot size. Document the uranium concentration distribution within the measured grains. Was it homogeneous within the measured grains? How do you match counted area of the spontaneous tracks and the laser-spot position? Give more details.
(6) The variable Dpar values could also be explained by not well-oriented (non-prismatic sections) grain faces. Especially, when considering the low track densities in all grains (Appendix B), there is likely a strong tendency to measure Dpar values in non-prismatic sections.
(7) There are some typos and generally, the text is not well written. Chapter 4.1 is a boring repetition of similar sentences for each sample just with changing numbers. Here, a summary of the most important findings and differences would be more informative than a verbalization of a data table.
Cited references:
d'Alessio, M.A., Blythe, A.E., Bürgmann, R., 2003. No frictional heat along the San Gabriel fault, California: Evidence from fission-track thermochronology. Geology, 31(6): 541-544.
Tagami, T., 2019. Application of Fission-Track Thermochronology to Understand Fault Zones. In: Malusà, M.G., Fitzgerald, P.G. (Eds.), Fission-Track Thermochronology and its Application to Geology. Springer International Publishing, Cham, pp. 221-233.
Comments for author File: Comments.pdf
Author Response
We very appreciate the reviewer's suggestions and they are very helpful for improving the paper. The attachment is the revision and detailed response for each question or comment. Anyway, many thanks. Hope the revision is better than before.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Glad to see that the authors were approachable - and willing to address the original issues raised. The revised version has been greatly improved.
Author Response
Nice to hear the reviewer's comments. Thanks for the reviewer's work for this paper writing. The reviewer's suggestion for this paper is very helpful to improve the paper. We revise again and add some significance and pictures. Hope it better than before. Please see the attachment.
We will ask the English service from MDPI for further English changes after the architecture of the paper is determined
Reviewer 3 Report
Please find my comments in the attached file (Minerals-1812405 R2).
Comments for author File: Comments.pdf
Author Response
Nice to hear from the reviewer's suggestion. The reviewer's suggestion is very helpful to improve the paper. We revise again and add some significance and pictures. Hope it better than before. Please see the attachment.
We will ask the English service from MDPI for further English changes after the architecture of the paper is determined
Author Response File: Author Response.pdf
