Sedimentological and Geochemical Characterization of the Early Cambrian Eastern Yunnan, Southwestern China

Round 1

Reviewer 1 Report

Please find the attached annotated file for detailed comments. However, the key suggestions are as follows:

Title of the manuscript:

1. Revise the title as: "Sedimentological and Geochemical Characterization of the Early Cambrian Eastern Yunnan, SW China".

Abstract section

2. what is the problem statement or research gap and based on it define the key objectives of the study.

3. write the conclusive statement regarding the key finding of the study in the end of abstract section.

Introduction section

4. Introduction section Lines 33-36: unclear statement. revise it by splitting the sentence for better understanding.

5. also define the significance of sedimentary lithofacies by referring to the available literature:

Facies analysis and distribution of Late Palaeogene deep-water massive sandstones in submarine-fan lobes, NW Borneo. Geological Journal 57, 4489-4507. doi:https://doi.org/10.1002/gj.4553

Facies Analysis and Sedimentary Architecture of Hybrid Event Beds in Submarine Lobes: Insights from the Crocker Fan, NW Borneo, Malaysia. Journal of Marine Science and Engineering 9. doi:10.3390/jmse9101133

6. what is meant by source area rock composition? delete the area to limit the term as source rock composition.

Geological setting section

7. refer to the published literature regarding the lithology of the stratigraphic formation.

8. Figure 1: the reported shallow water depositional setting is too broad and general. refer to the particular component of the shallow water shelf.

9. Figure 1: The sedimentary log is not refined. please add the details and include various sedimentary structures or textural details for sandstone, and siltstone/shale  beds

10. Add the scale of the geological map in the figure 1A

11. mark the outcrop location and the sample locations in the map

Material and Method section

12. include a table to show the dataset details of 52 sandstone/shale samples

13. material or method section should be revised with more explanation of petrographic and geochemical analyses.

Results section

14. Result subsection 4.1 has a higher similarity index. rephrase the subsection.

15. Figure 2: Include the scale of the field image for each picture. also, check the figure number.

 16. Figure 3: please revise the figure caption and mention the details of each cross plot for clarity

17. Figure 5: use the high resolution figure and replace the blur one.

Diuiscussion section

18. revise the discussion to avoid high similarity index

Conclusion section

19. the conclusion section is the repetition of results and discussion. revise the conclusion section

general comment

20. Plagiarism report show the similarity is about 41% excluding the bibliography. rephrase the similar text and improve the writing of the manuscript.

Comments for author File: Comments.pdf

Author Response

Please see attachment file “Response to Reviewer 1 Comments”

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

Thank you for the opportunity to review the manuscript “Tracking depositional and geochemical variations in the early Cambrian eastern Yunnan, SW China: Insights from sedimentology and geochemistry”. The manuscript is well-written and contains an impressive and novel dataset. However, the results of the study are disjointed in that it is unclear what the relationship between sedimentological characteristics and the geochemical data. Based on my thorough review, I recommend be accepted pending major revisions. My general comments include:

§  The manuscript presents two different research components: (1) characterization of the sedimentology and interpretation of the depositional environments; (2) the use of major elements and REE to determine the provenance. While both components relate to the HJS Formation, there is no clear connection between the dataset and the hypothesis that is being tested. Further, both components lack a spatial or temporal perspective

§  The sedimentological characterization and interpretation of depositional environments lacks a spatial and temporal context. Given that this study examined multiple outcrops it would be beneficial to provide a measured section showing the variation in lithofacies over time. This will also provide evidence/support for the environmental interpretation.

§  Regarding the major element and REE concentrations, it is unclear how this data relates to the sedimentological data. It would be beneficial to show major element concentrations per lithofacies to understand provenance. As previously noted, it would also be valuable to show the temporal variation in major elements with the measured section which will help elucidate changes in the depositional setting and weathering conditions. Specifically, can the elemental data help differentiate deltaic versus shallow shelf depositional environments?

§  A question worth pre-emptively addressing is what is the benefit of using REE to derive provenance. For decades sedimentologists have used point counting QFL ternary diagrams to interpret provenance (e.g., Gazzi, 1966; Dickinson and Suczek, 1979; Dickinson, 1985; 1988). Figure 8 illustrates these QFL diagrams. Why is the REE provenance approach better?

§  The authors note weathering under semi-arid to humid climates, however, Figure 9 illustrates a wide range of climates from Arid to Humid. It would be beneficial to expand on this interpretation. Is this data reliable, and there is just a fluctuating climate during that time? The GLC samples exhibit the greatest range in CIA 71.24 to 88.33, suggesting intermediate to extreme weathering. Are there any sedimentological trends that correspond to these changes?

§  The REE data suggest that felsic rocks constitute that sediment source, which is supported by the QFL, showing a quartz-dominated composition sourced from recycled orogen. How does this relate to the lithofacies and depositional environment?

There are a few instances where there are spelling or grammatical issues (See Manuscript PDF Comments). These issues should be addressed to improve readability. I recommend addressing the comments listed above; however, the manuscript needs major revisions before publication.

Kindest regards,
Reviewer

Comments for author File: Comments.pdf

See the attached manuscript comments for the authors. Highlighted text indicates questions, concerns, or grammatical issues.

Author Response

Please see attachment file “Response to Reviewer 2 Comments”.

Author Response File: Author Response.pdf

Reviewer 3 Report

I appreciate the chance to review “Tracking depositional and geochemical variations in the early Cambrian eastern Yunnan, SW China: Insights from sedimentology and geochemistry” by Xiaoxia Peng, Zexin Fang, Xin Cheng, Ling Guo, and Jianni Liu.

This study seems like a fairly straightforward examination of these sedimentary deposits and let me start by stating that this is a nice body of data that likely took significant effort to collect, process and analyze, so I don’t want to downplay that. But my main concern is what the main point the authors are trying to convey with this work. I think there are some major questions to be answered here to clarify what the direction of this paper actually is, because it’s not readily apparent here.

I don’t think they make the connection here between these discrete results. They show lithology, and geochemistry but not necessarily the link or even why we should care about it that matter. There is enough work here to make that connection, but the authors need to be more explicit about what exactly they are doing. Are they trying to show what the depositional environments were? They touch on that but don’t necessarily make much of a case for it. Perhaps a composite stratigraphic column or fence diagram showing the facies relationships – deltaic deposits should be readily apparent in this sense. Are we seeing geochemical variations, I can’t necessarily tell because I don’t have a sense of the stratigraphic location, are all samples from the same geographic location from the same stratigraphic level? Are they collected next to each other, or how far apart? What was the lithology of the collected samples? Even the most basic question of how thick is this formation at these locations?

In figure 1, the stratigraphic column is really difficult to see the lithology, can’t distinguish the coarse form gravelly, etc.. Is this stratigraphic column complete or composite?

From the methods, were the samples processed at all for xrf and icp-ms, these are two different instruments. I would assume they were but have no idea how. Powdered? Digested? Were the samples analyzed on both instruments, in this case, are the results an average of this? Or were some run on xrf and some by icp-ms, it is unclear. I mention because depending on the instrument there are different sensitivities with the results.

To this end in discussion on paleoweathering and paleoclimate ratios, there needs to be clarity on what these ratios are used for and how upfront, a sentence or two on how and why it is applicable here. If this material is already recycled or clay-rich it will likely have artificially high CIA values. Plus, CIW and PIA were developed considering paleosols or more terrestrial material, that might merit mentioning. It is unclear what the lithology of the sediments processed for geochemistry is. Some of the values presented here could likely be included in the results section. The last paragraph in this section seems relevant upfront.

Similarly, with lithofacies, its tough to understand relationship without the stratigraphic or geographic context of their locations. Are the cut and fill apparent in outcrop? Also, with the overbank deposition, is there any indication of pedogenesis or swamp/marsh features? In shallow shelf, I would hesitate to say tidal bedding forms from wave action, but that’s likely a personal grievance.

Minor point – in line 51, “famous” is a subjective term.

The English was fine, no major issues, a few misspelled words and a few awkward phrases that should be cleared up after some minor editing. For example, the Section 4.4 header should be "Rare", and I assume in Table 1 it is trough cross-beds, not through cross-beds.

Author Response

Please see attachment file “Response to Reviewer 3 Comments”.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Abstract section:

conclude the abstract with global or regional significance or application of the study.

Keywords:

add the keywords:

shallow marine depositional environment; chemical weathering

Geological setting section:

Figure 1: what is the vertical scale of the sedimentary log. please add the vertical scale to know the thickness of lithologies. Secondly, the depositional environment is interpreted as delta or tidal flat. please refine the interpretation by differentiating the various types of depositional environments.

Similarity index excluding bibliography is 34%. please see the attached file to reduce the similarity index.

Comments for author File: Comments.pdf

Author Response

Please see attachment file "Response to Reviewer 1 Conmments Round 2"

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

Thank you for the opportunity to review the revised manuscript now titled “Sedimentological and Geochemical Characterization of the Early Cambrian Easter Yunnan, SW China”. The manuscript is well-written, and a significant amount of work has been completed revising the manuscript. In its present form, the manuscript is still disjointed in terms of the datasets and how they are being utilized to interpret the depositional environment, paleoclimate, and provenance. Based on my thorough review, I recommend accepting it pending minor revisions. My recommendations to improve the manuscript for acceptance are the following:

§  There is insufficient sedimentological data to support environmental/depositional settings. Further, the manuscript is written (lines 45-48) in a manner that suggests that the geochemical data can help constrain the depositional environment. The author’s response notes that the elemental data cannot distinguish between deltaic and shallow marine shelf environments. This contradicts the author’s note in Response 1 that major element content is controlled by the sediment environment. Regardless, the elemental content should be binned by environmental settings to either support or refute the use of elements in environmental interpretations. I recommend running a principal component analysis or factor analysis to assess whether any specific elements load onto a given lithofacies.

§  The sedimentological data and descriptions are insufficient to support environmental interpretations. Identification of lithofacies and facies associations is critical for interpretation. Currently, no facies associations are presented. It would be beneficial to provide a figure illustrating depositional stacking patterns that are observed and supporting your environmental interpretations.

§  A conceptual model illustrating the depositional environment and its influence by paleoclimate, weathering, and provenance would help explain the lithofacies and geochemical trends.

§  While Table 1 is useful in providing more detailed information on the sample sites, it does not illustrate the relationship between lithofacies and major-trace elements as suggested in Response 3.

§  Finally, the authors need to clarify that sedimentological characterization was used to constrain the depositional environment, while geochemical data was used to constrain paleoclimate and provenance. The manuscript presents these methods as integrated in constraining all three.

There are a few instances of spelling or grammatical issues (See Manuscript PDF Comments). These issues should be addressed to improve readability. I recommend addressing the comments above; however, the manuscript needs major revisions before publication.

Kindest regards,
Reviewer

Addressed in general comments and suggestions for authors.

Author Response

Please see the attachment file"Response to Reviewer 2 Comments Rounds 2"

Author Response File: Author Response.pdf