Paleoclimatic and Redox Condition Changes during Early-Middle Jurassic in the Yili Basin, Northwest China

Round 1

Reviewer 1 Report

The manuscript is about paleoclimatic and redox condition changes during Early-Middle Jurassic in the Yili Basin. The scope of this article is consistent with the requirements of the Minerals Journal, but it requires major revision in accordance with the comments below:

1. Abstract is too long. According to the instructions for authors, the abstract should be a total of about 200 words maximum.
2. I think that introduction is too short. Avoid lumping references as in: [1-3], [4-7], [8-11], [12-15], [16,17] [18-21], [22-24], [25-28]. Instead summarise the main contribution of each referenced paper in a separate sentence.
3. Figure 3: Should be similarity not smiliarity.
4. The Discussion section is about new results, and should summarize the data presented in the section Results. Therefore, I propose to combine sections 4 and 5 and name it Results and Discussion.

Author Response

Response to Reviewer 1 Comments

 

We gratefully thank the reviewer for your time spend making the constructive remarks and useful suggestions, which has significantly raised the quality of the manuscript and has enable us to improve the manuscript. Each suggested revision and comment, brought forward by the reviewers was accurately incorporated and considered. All corrections are highlighted by red in the revised manuscript for tracking easily.

Point 1: Abstract is too long. According to the instructions for authors, the abstract should be a total of about 200 words maximum.

Response 1: Thanks for the reviewer’s suggestion, we have rewritten the abstract.

Abstract: The Jurassic was broadly a typical “greenhouse” period, and characterized by global warming, marked by a significant peat-forming interval. However, studies on Jurassic climate and envi-ronment have mainly focused on marine records and only a few on terrestrial sediments. Yili Basin, a mid-latitude terrestrial basin in present Northwest China, included accumulation of the most important recoverable coal seams. In this study, geological data, clay mineral analysis and palynological assemblages were employed on the fine-grained samples from Su’asugou section in southern Yili Basin. In particular, the factors (paleoclimate, depositional conditions and paleo-vegetation) impacting peat accumulation were investigated. The results suggest these clastic rocks may have been derived from exposed Carboniferous rocks in a continental arc en-vironment. The paleoclimate in the Yili basin was mainly warm and humid during early-Early Jurassic Badaowan Formation and Middle Jurassic Xishanyao Formation, which contributed to a high sedimentary rate and a high productivity of peat-forming paleo-vegetation that was pre-served under dysoxic conditions. In contrast, between these two formations, the late-Early Juras-sic Sangonghe Formation was an interval of relatively aridity expressed by the appearance of red beds preserved under a more hypoxic sedimentary conditions, and with an interruption in peat forming and preservation.

Point 2: I think that introduction is too short. Avoid lumping references as in: [1-3], [4-7], [8-11], [12-15], [16,17] [18-21], [22-24], [25-28]. Instead summarise the main contribution of each referenced paper in a separate sentence.

 

Response 2: Thanks to you for your good comment, we have rewritten the introduction.

 

1. Introduction

The paleoclimate of the Jurassic period is generally considered as a classical greenhouse with high atmospheric levels of CO₂ [1], a global perturbation of the carbon cycle [2], and major marine biological changes [3]. During the Lower and Middle Jurassic, data from clay mineralogy [4], geochemistry [5,6], and paleontology [7] general-ly point to a warm and equable climate, but with pronounced fluctuations. The Jurassic was also characterized by the worldwide preservation of organic-rich sediments [8] and by expanded tropical climate zones that feature considerable coal accumulation [9]. Possible explanations include elevated atmospheric CO₂ levels that were partly sequestered geological storage of carbon [10,11], and that triggered and/or amplified the climatic warming and anoxia conditions in global oceans and in terrestrial basin depositional environments [12,13]. Most Jurassic paleoclimate studies, however, have focused on marine sediments; and only a few have examined middle-latitude terrestrial sediments [14]. Therefore, it is crucial to include studies of terrestrial ecosystems during the Jurassic in order to gain a better understanding of paleoclimatic fluctuations and redox changes in terrestrial environments.

Various proxies have been used to reconstruct paleoclimate and redox conditions [15,16], In addition to geochemical proxies [17,18], clay mineralogy is valuable paleo-climate proxy [19], especially to constrain variations in humidity and aridity in the hinterlands [20,21]. Palynological data enables reconstruction of terrestrial ecosystem responses to changes in environment [22]. However, any single proxy can be affected by factors in addition to local climate; therefore, lithologic features in the sediments, such as organic preservation and/or red-bed occurrences should be included.

Coal is a significant terrestrial sink of organic carbon in the long-term global car-bon cycle, and this sequestration is an important regulator of atmospheric CO₂ levels and paleoclimate [23,24]. Yet, the processes that control the peat accumulation in terrestrial basins remain poorly understood.

Jurassic coal-bearing strata are widely distributed throughout the world, especially in northern China. The Jurassic stratigraphy in China is dominated by continental sediments [25], and a number of studies have noticed fluctuations of paleoclimate and redox conditions during the Early to Middle Jurassic transition in northern China [26]. The Yili Basin is a relatively large coal-bearing basin in the Xinjiang Province of Northwest China. Its Lower-Middle Jurassic terrestrial strata had a near-continuous deposition; thereby providing an ideal location and materials for studying the history of the terrestrial ecological system.

In this paper, we examined geological characteristics, clay minerals and palynological data from Lower through Middle Jurassic strata in the Yili Basin in order to reconstruct the regional paleoclimatic and depositional redox history and the associated episodes of peat accumulation and preservation. Mineralogical and maceral composition of coal seams, coupled with sedimentological, palynological and stable isotope data [27,28], provide other essential proxies for paleoclimate and depositional conditions and for the types of paleo-vegetation that contributed to peat accumulation.

 

Point 3: Figure 3: Should be similarity not smiliarity.

 

Response 3: Have done.

 

Figure 3 Cluster analysis of trace elements. The labeled categories are discussed in the text.

 

Point 4: The Discussion section is about new results, and should summarize the data presented in the section Results. Therefore, I propose to combine sections 4 and 5 and name it Results and Discussion.

 

Response 4: We gratefully appreciate for the valuable suggestion. We did try to combine the sections 4 and 5 and named it Results and Discussion. Unfortunately, we found it was not better than the current. We have done a nice separation of the two, which is the way most science papers should be presented.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript titled "Paleoclimatic and redox condition changes during Early-Middle Jurassic in the Yili Basin, Northwest China" presents a very interesting study that attempts to investigate the paleoclimatic conditions of Western Tethys by conducting detailed mineralogical, geochemical and palynological research on the Yili basin in NW China. The manuscript is well written and the proposed research has been appropriately designed. There are only few minor corrections that should be made prior to publication in the Journal Minerals. Therefore, Minor Revision is suggested. 

1. The UCC-normalised REE patterns show significant positive Eu anomalies. Please provide a possible interpretation. In many cases Eu anomalies can be attributed to the presence plagioclase, and/or changes in oxygen fugacity (fO2) and pH. These parameters may further contribute to the interpretation of the physicochemical conditions.
2. Line 35: ...and marked... Delete "and"
3. Line 18: deposits
4. Line 113: mudstones and siltstones

Author Response

Response to Reviewer 2 Comments

 

We gratefully thank the reviewer for your time spend making the constructive remarks and useful suggestions, which has significantly raised the quality of the manuscript and has enable us to improve the manuscript. Each suggested revision and comment, brought forward by the reviewers was accurately incorporated and considered. All corrections are highlighted by red in the revised manuscript for tracking easily.

Point 1: The UCC-normalised REE patterns show significant positive Eu anomalies. Please provide a possible interpretation. In many cases Eu anomalies can be attributed to the presence plagioclase, and/or changes in oxygen fugacity (fO₂) and pH. These parameters may further contribute to the interpretation of the physicochemical conditions.

Response 1: We are very sorry for the mistake, we have supplied a possible interpretation in the manuscript. The significant Eu anomalies appear to be related to hydrothermal circulation [40]. U deposit in Yili basin is a typical hydrothermal uranium deposit, hydrothermal plays an important role in generating element.

Point 2: Line 35: ...and marked... Delete "and"

 

Response 2: Line 15 Have done

 

Point 3: Line 18: deposits

 

Response 3: Have done

 

Point 4: Line 113: mudstones and siltstones

 

Response 4: Have done

 

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors did all corrections from the previous version; however, some small points need to be corrected. I noted them in attached copy.

Of note, the authors should consider to use SEM analysis in their future studies in order to have more robust discussion elemental compositions and mineralogical composition when the elemental proxies are applied.

Furthermore, it would be nice to provide snaps of identified palynomorphs.

Overall, after the suggested corrections done, paper will send to production. 

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 3 Comments

 

We gratefully thank the reviewer for your time spend making the constructive remarks and useful suggestions, which has significantly raised the quality of the manuscript and has enable us to improve the manuscript. Each suggested revision and comment, brought forward by the reviewers was accurately incorporated and considered. All corrections are highlighted by red in the revised manuscript for tracking easily.

Point 1: the authors should consider to use SEM analysis in their future studies in order to have more robust discussion elemental compositions and mineralogical composition when the elemental proxies are applied.

Response 1: We appreciate for the reviewer’s valuable suggestion, we would consider the SEM analysis in our future studies.

Point 2: Furthermore, it would be nice to provide snaps of identified palynomorphs.

 

Response 2: We are appreciative of the reviewer’s suggestion. Indeed, it will be more convincing if we get a comparative assessment on palynology assemblages to discuss the palaeoclimate conditions. However, all the palynological data have listed in the manuscript without snaps. The limitation of sample amount and time may be the main reason. Therefore, we seek for the reviewer’s understanding. Many thanks for your kind help.

 

Specific comments:

1. Line 215: Deng (2017) what kind of climate conditions were reported in this study and is the palaeobotanical assemblages in agreement with identified palynofloral assemblages?

Response: The changes in floral compositions indicate that a dramatic climate event occurred in North China with a remarkable temperature rising and aridity during the late Early Jurassic. Cycadopites sp. and Osmundacidites from our studied section were similar with Deng (2017), which are usually adapted to humid and warm climate.

 

2. Line 231: Delete “zircons”

Response: Have done

 

3. Figure 6: please report horizontally

Response: Have done

 

4. Line 284: “reviewed by Algeo, 2010”

Response: Have done

 

5. Line 300: some geological ratios

Response: Have done

 

6. Line 314: Delete “Kaolinite/Illite”

Response: Have done

 

7. Line 398: Delete “[38,100]”

Response: Have done

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have addressed most of the comments; they have also tried to make changes according to the reviewers’ suggestions. After revisions, the quality of the manuscript has been adequately enhanced. Therefore, the manuscript could be considered for the publication in the Journal. 

Author Response

We gratefully thank the reviewer for your time spend making the constructive comments, which has significantly raised the quality of the manuscript and has enable us to improve the manuscript. We have rephrased the introduction follow your suggestion.

 

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This paper presents the results of a study of 21 samples of Early-Middle Jurassic sediments of the Iili Basin, which allowed us to conclude about changes in the paleoclimate and redox conditions during their formation. The study of the distribution of redox-sensitive elements (V, Ni, Mo, and Co) and their indicator ratios established the conditions of precipitation within the Early Jurassic and Middle Jurassic sediments. The results obtained showed that the paleoclimate was relatively warm and humid, the accumulation of Jurassic coal in the Iili Basin was associated with paleoclimatic and redox conditions. This technique provides information about paleoclimate which led to high paleoproductivity and created a sedimentary environment that contributes to the enrichment of coal by increasing the deposition rate; organic matter is preserved in a disoxic state.

The interpretation of the data obtained appears to have been performed well; the paper adds valuable new information concerning our knowledge of Jurassic coal accumulation in the Iili Basin, which was associated with paleoclimatic and redox conditions.

I can recommend this article for publication in the Minerals, but with minor corrections.

The comments relate to the statistical processing of analytical data. They are intended to improve a future paper, which must be focused on the statistical data analysis. So, Figure 4 shows the linear relationships between the concentrations of chemical elements. It is not very clear why the values of R2 are given, and not just R. As a rule, R2 refers to the coefficients of determination. You should also to determine the prediction intervals and the confidence limits for the coefficients of correlation.

Author Response

We are grateful to the reviewer for your constructive comments and suggestions on our manuscript. We have revised the manuscript following suggestions and are here submitting a revised version. All corrections are highlighted by red in the revised manuscript for tracking easily.

Point 1: The comments relate to the statistical processing of analytical data. They are intended to improve a future paper, which must be focused on the statistical data analysis. So, Figure 4 shows the linear relationships between the concentrations of chemical elements. It is not very clear why the values of R² are given, and not just R. As a rule, R² refers to the coefficients of determination. You should also to determine the prediction intervals and the confidence limits for the coefficients of correlation.

Response 1: We do appreciate the reviewer’s kind suggestion. We have removed Figure 4, and added V_EF and Mo_EF data as a proxy to discuss the redox conditions. Meanwhile, we supplied the sedimentology characteristics as another evidence to be more convincing.

Reviewer 2 Report

The manuscript under consideration tries to decipher the sedimentary conditions of the Jurassic terrigenous rocks from one of the terrestrial basins of North China. The topic is interesting. However, I am not sure that it fits the scope of MINERALS.

I could not finish reading this work to the end due to its many serious shortcomings and errors. The language of the article requires significant editing.

The figures are generally of good quality, but some of them do not correspond to the text. For example, in Figure 1 it is difficult to see the configuration of the Yili basin. In Figure 2, the red burnt stratum is shown to be no more than 5 m thick and is located within Sangonghe Fm, while the text describes it as located in the Xishanyao Fm and 20 m thick (Lines 75-77).

It is unclear from Section 3, how and using what technique the samples were milled. It is important, because the samples might be contaminated with the redox-sensitive elements. Which analytical equipment was used and in what lab the XRD and ICP-MS analyses were performed? Why the presented ICP-MS data include concentrations for 10 elements only? The analysis allows many more. According to Lines 119-120, the contents of elements in Table 1 (ICP-MS data) are indicated in molecular percentages, that is nonsense.

When discussing the changing sedimentary conditions using geochemical indicators (Section 5.1), the authors either do not make the necessary references or make incorrect references. The logic of reasoning is also incorrect sometimes. For instance, the authors wrote (Lines 167-170) “V/(V+Ni) ratios of 0.46-0.60 indicate dysoxic conditions, 0.54-0.82 signal anoxic conditions, and >0.84 are indicative of oxic conditions. According to the testing results (Figure 3), the V/(V+Ni) ratios for all the samples are slightly high (0.69-0.92) suggesting a dysoxic conditions”. Logical would be saying that the V/(V+Ni) ratios for all the samples (0.69-0.92) suggest alternating oxic-dysoxic conditions. Anoxic means no oxygen, while dysoxic  means low oxigen. What is signal anoxic is not explained. Who determined the indicative ranges of V/(V+Ni) is unclear. In addition, the terms dysoxic and hypoxic are close in meaning. Readers should at least understand how the authors distinguish between oxic, dysoxic, hypoxic, and anoxic. No explanation is present.

Reference 45 and 46 indicate the same work, so that all the following references must be renumbered.

In summary, I recommend rejection.

Comments for author File: Comments.pdf

Author Response

We are grateful to the reviewer for your constructive comments and suggestions on our manuscript. We have revised the manuscript following suggestions and are here submitting a revised version. All corrections are highlighted by red in the revised manuscript for tracking easily.

 

Point 1: I could not finish reading this work to the end due to its many serious shortcomings and errors. The language of the article requires significant editing.

Response 1: We are very sorry for the mistakes in this manuscript and inconvenience they caused in your reading. All the grammar and spelling issues in the manuscript have been modified. All the revisions in the manuscript have been highlighted by red.

 

Point 2: The figures are generally of good quality, but some of them do not correspond to the text. For example, in Figure 1 it is difficult to see the configuration of the Yili basin. In Figure 2, the red burnt stratum is shown to be no more than 5 m thick and is located within Sangonghe Fm, while the text describes it as located in the Xishanyao Fm and 20 m thick (Lines 75-77).

Response 2: Thanks, as for the reviewer’s concern, we have revised Figure 1 and Figure 2. The red burnt rock occurred in Xishanyao Formation, and the red beds in Sangonghe Formation was siltstone in red colour.

 

Point 3: It is unclear from Section 3, how and using what technique the samples were milled. It is important, because the samples might be contaminated with the redox-sensitive elements. Which analytical equipment was used and in what lab the XRD and ICP-MS analyses were performed? Why the presented ICP-MS data include concentrations for 10 elements only? The analysis allows many more. According to Lines 119-120, the contents of elements in Table 1 (ICP-MS data) are indicated in molecular percentages, that is nonsense.

Response 3: Follow your suggestions, we have provided the data in the Material and Methods section. The unit of the values have been supplied in Table 1, within all contents of the trace element.

The XRD was carried at using a PANalytical X’Pert PRO diffractometer with CuKα radiation, Ni filter and filiter and divergence slit of 0.38mm, under 40kv voltage and 25 mA current, at ALS Chemex (Guangzhou) Ltd..

Identification of clay minerals was made by comprehensive comparison of the three XRD diffractograms using the Highscore.

Trace elements were measured by inductively coupled plasma mass spectrometry (ICP-MS) with A Finnigan MAT Element Ⅱ mass spectrometer at ALS Chemex (Guangzhou) Ltd..

 

Point 4: When discussing the changing sedimentary conditions using geochemical indicators (Section 5.1), the authors either do not make the necessary references or make incorrect references. The logic of reasoning is also incorrect sometimes. For instance, the authors wrote (Lines 167-170) “V/(V+Ni) ratios of 0.46-0.60 indicate dysoxic conditions, 0.54-0.82 signal anoxic conditions, and >0.84 are indicative of oxic conditions. According to the testing results (Figure 3), the V/(V+Ni) ratios for all the samples are slightly high (0.69-0.92) suggesting a dysoxic conditions”. Logical would be saying that the V/(V+Ni) ratios for all the samples (0.69-0.92) suggest alternating oxic-dysoxic conditions. Anoxic means no oxygen, while dysoxic means low oxigen. What is signal anoxic is not explained. Who determined the indicative ranges of V/(V+Ni) is unclear. In addition, the terms dysoxic and hypoxic are close in meaning. Readers should at least understand how the authors distinguish between oxic, dysoxic, hypoxic, and anoxic. No explanation is present.

Response 4: We have rewritten the section. Using V/(V+Ni), U/Th, V_EF and Mo_EF data as a proxy to discuss the redox conditions. Meanwhile, we supplied the sedimentology characteristics as another evidence to be more convincing.

 

Point 5: Reference 45 and 46 indicate the same work, so that all the following references must be renumbered.

Response 5: Thanks, we have renumbered all the references.

 

Specific comments:

1. Line 64-65: Modified the description of the Yili Basin

Response: Have done

The Yili Basin is a composite intermontane basin evolved from the middle Tianshan microcontinent [27, 31-33]

2. Modified the location of the Yili Basin in Figure 1

Response: Have done

3. Lack of symbols in Figure 2

Response: Have done

Author Response File: Author Response.pdf

Reviewer 3 Report

The study evaluates geological characteristics (elemental, mineral and sporopollen composition) from Early-Middle Jurassic strata in the Yili Basin in order to construct the paleoclimatic change and redox history. The study is interesting and easy to follow; its technical quality is good as well. Therefore, it can be accepted for the publication. Nevertheless, as there are still some issues that are to be addressed,  minor revision prior to its publication is recommended.

Novelty has been clearly stated in abstract (which is good) but it is a pity that the implications are only marginally mentioned in the text. Therefore,  I suggest to highlight these implications e.g. within the conclusions.

Fig. 1 consists of three diagrams - A, B and C, but the label B is not well visible in the diagram.

Table 1 Trace elements and ratios. Please provide the dimension (unit) of these values, either in the table itself or within its caption. Now, it is only mentioned in the text that these values are molar percentges. Please provide more details (in the text), e.g. to what basis these percentages are related (i.e. what is 100% - total element molar amount, sum of the elements etc.)

Table 3 - Sporopollen occurrence in the studied samples. Are these sporopollens ordered according to their abundance? If so, it could be mentioned (it is interesting information)

Fig. 4 - Relationships among elements. Values plotted on vertical axes require more details/explanation. For example, V (%) ranged up to 120-180% etc. look strange without any other description/comment. Please provide more details in the text/table caption and clarify.

Fig.5 - I appreciate that huge amount of information is incorporated in this well-organized and illustrative figure. Perhaps, in XRD patterns, the peak labels are not well readable. If it is not needed for some other evaluation, I suggest to delete the numbers with Angstroms and use only the abbreviations of the identified minerals (that could be enlarged). And if these values are needed, they could be mentioned within the caption, legend or below the figure.

Author Response

We are grateful to the reviewer for your constructive comments and suggestions on our manuscript. We have revised the manuscript following suggestions and are here submitting a revised version. All corrections are highlighted by red in the revised manuscript for tracking easily.

 

Point 1: Novelty has been clearly stated in abstract (which is good) but it is a pity that the implications are only marginally mentioned in the text. Therefore, I suggest to highlight these implications e.g. within the conclusions.

Response 1: Thanks for the reviewer’s suggestion, we have heightened the conclusions.

6. Conclusions

Fine-grained samples from the Early-Middle Jurassic sediments in Yili Basin were determined to infer the palaeoclimate changes and redox conditions during their sedimentation. Through a combination of field and laboratory methods, the redox-sensitive element U, Th, V and their ratios suggest dysoxic conditions within the Early Jurassic Badaowan Fm. and the Middle Jurassic Xishanyao Fm. Together with the sedimentology characteristics, the Early Jurassic Sangonghe Fm. was deposited under predominantly dysoxic condition of deposition. Multi-proxies show that the palaeoclimate was relatively warm and humid, but more warming in the Early Jurassic Sangonghe Fm., as well as the redox conditions shown.

Peat accumulation in the Yili Basin during the Early-Middle Jurassic resulted from the palaeoclimatic and redox conditions. In the Badaowan Formation and Xishanyao Formation (peat-forming periods), the paleoclimate was dominated by a warm and humid climate. Such climates are conducive to not only high paleoproductivity, but also create a sedimentary environment, which was beneficial to the enrichment of peat by increasing the deposition rate, lead peat-accumulation under dysoxic condition. By contrast, because of the warmer palaeoclimate and more dysoxic condition, red sediments appearance, and a hiatus in coal deposition, which may be a regionally climate fluctuation in Northwest China.

 

 

Point 2: Fig. 1 consists of three diagrams - A, B and C, but the label B is not well visible in the diagram.

Response 2: Thanks, as for the reviewer’s concern, we have modified the Figure 1.

 

Point 3: Table 1 Trace elements and ratios. Please provide the dimension (unit) of these values, either in the table itself or within its caption. Now, it is only mentioned in the text that these values are molar percentges. Please provide more details (in the text), e.g. to what basis these percentages are related (i.e. what is 100% - total element molar amount, sum of the elements etc.)

Response 3: Follow your suggestions, the unit of the values have been supplied in Table 1, within all contents of the trace element.

 

Point 4: Table 3 - Sporopollen occurrence in the studied samples. Are these sporopollens ordered according to their abundance? If so, it could be mentioned (it is interesting information)

Response 4: We are appreciative of the reviewer’s suggestion. Indeed, it will be more convincing if we get a comparative assessment on palynology assemblages to discuss the palaeoclimate conditions. However, all the palynological data have listed in the manuscript without snaps. The limitation of sample amount and time may be the main reason. Therefore, we seek for the reviewer’s understanding. Many thanks for your kind help.

 

Point 5: Fig. 4 - Relationships among elements. Values plotted on vertical axes require more details/explanation. For example, V (%) ranged up to 120-180% etc. look strange without any other description/comment. Please provide more details in the text/table caption and clarify.

Response 5: Follow the reviewer’s suggestion, we have removed Figure 4, and added V_EF and Mo_EF data as a proxy to discuss the redox conditions. Meanwhile, we supplied the sedimentology characteristics as another evidence to be more convincing.

 

Point 6: Fig.5 - I appreciate that huge amount of information is incorporated in this well-organized and illustrative figure. Perhaps, in XRD patterns, the peak labels are not well readable. If it is not needed for some other evaluation, I suggest to delete the numbers with Angstroms and use only the abbreviations of the identified minerals (that could be enlarged). And if these values are needed, they could be mentioned within the caption, legend or below the figure.

Response 6: Thanks, as the reviewer’s comment, we have deleted the XRD diagrams.

Author Response File: Author Response.pdf

Reviewer 4 Report

The aim and organization of MS is quite well. For instance, providing elemental, mineralogical and palynological data is very good approach; however, I cannot say about some parts of discussion. Firstly, the authors should avoid to use following terms; 1) coal-forming period, 2) coal-accumulation and 3) sporopollen. It is highly recommending to use following 1) peat-forming, 2) peat-accumulation and 3) palynomorphs/palynological data. I added related notes in attached revised MS. Secondly, in the material and method section the authors provide data about used XRD equipment and applied software. Furthermore, the authors should provide a table that including lithological features and sampling intervals of the studied samples. The authors should be careful about the X-Y plotting data in the Figure 4. Majority of plotting data do not have any statistical significance. I think that the authors should remove this figure or re-asset their data using another statistical method (e.g., factor analysis or hierarchical cluster). Thirdly, the authors should also provide plates that including snaps of identified palynomorphs, because such kind of plates or figures are essential for palynological studies. Finally, the authors should make more detailed discussion about palaoeclimatic conditions using palynological data, since such kind of data could provide more accurate data rather than elemental proxies and clay mineralogy. Therefore, I suggest to the authors that they should more detailed discussions in the section 5.3. Otherwise, this section sounds like a literature overview. Overall, I encourage to authors for publication after suggestion done. Therefore, I would like to re-consider the MS after suggested corrections done. I also noted some suggestions in the revised MS.

Comments for author File: Comments.pdf

Author Response

We are grateful to the reviewer for your constructive comments and suggestions on our manuscript. We have revised the manuscript following suggestions and are here submitting a revised version. All corrections are highlighted by red in the revised manuscript for tracking easily.

Point 1: Firstly, the authors should avoid to use following terms; 1) coal-forming period, 2) coal-accumulation and 3) sporopollen. It is highly recommending to use following 1) peat-forming, 2) peat-accumulation and 3) palynomorphs/palynological data. I added related notes in attached revised MS. 

Response 1: As for the reviewer’s concern, all the terms in the manuscript have been modified according to the comments.  Chang coal-forming period to peat-forming, change coal-accumulation to peat-accumulation, change sporopollen to palynological data.

 

 

Point 2: Secondly, in the material and method section the authors provide data about used XRD equipment and applied software.

Response 2: We have provided the data in the Material and Methods section.

 

The XRD was carried at using a PANalytical X’Pert PRO diffractometer with CuKα radiation, Ni filter and filiter and divergence slit of 0.38mm, under 40kv voltage and 25 mA current, at ALS Chemex (Guangzhou) Ltd..

 

Identification of clay minerals was made by comprehensive comparison of the three XRD diffractograms using the software Highscore.

 

 

Point 3: Furthermore, the authors should provide a table that including lithological features and sampling intervals of the studied samples.

Response 3: We are very sorry for the negligence. A list of sample lithology has been added in Table 2. Taking account of various circumstances, location and transportation, the sampling interval of the studied samples was one sample for each layer, without accurate data.

 

Point 4: The authors should be careful about the X-Y plotting data in the Figure 4. Majority of plotting data do not have any statistical significance. I think that the authors should remove this figure or re-asset their data using another statistical method (e.g., factor analysis or hierarchical cluster)

Response 4: Follow the reviewer’s suggestion, we have removed Figure 4, and added V_EF and Mo_EF data as a proxy to discuss the redox conditions. Meanwhile, we supplied the sedimentology characteristics as another evidence to be more convincing.

Point 5: Thirdly, the authors should also provide plates that including snaps of identified palynomorphs, because such kind of plates or figures are essential for palynological studies

 Finally, the authors should make more detailed discussion about palaoeclimatic conditions using palynological data, since such kind of data could provide more accurate data rather than elemental proxies and clay mineralogy.

Response 5: We are appreciative of the reviewer’s suggestion. Indeed, it will be more convincing if we get a comparative assessment on palynology assemblages to discuss the palaeoclimate conditions. However, all the palynological data have listed in the manuscript without snaps. The limitation of sample amount and time may be the main reason. Therefore, we seek for the reviewer’s understanding. Many thanks for your kind help.

 

Point 6: I suggest to the authors that they should more detailed discussions in the section 5.3. Otherwise, this section sounds like a literature overview. 

Response 6: Considering the reviewer’s comment, we have rewritten the section 5.3.

Specific comments:

1. Line 11: Change “time” to “period

Response: Have done

2. Line 12: Change “coal-forming” to “peat-forming”

Response: Have done

3. Line 24: Change “coal deposition” to “peat-forming”

Response: Have done

4. Line 25: Change “coal accumulation” to “peat accumulation”

Response: Have done

5. Line 47-50: Supply “Furthermore, mineralogical and maceral composition of coal seams along with sedimentological palynological and stable isotope data could provide essential data for palaeoclimatic and depositional conditions, and palaeovegetation during peat-accumulation.”

Response: Have done

6. Line 52: Change “sporopollen” to “palynological data”

Response: Have done

7. Line 57: Modified format

Response: Have done

8. Line 79: Modified “highly coal-bearing”

Response: Have done

9. Line 81: About “burnt rock”

Response: Shi (2016) considered that the burnt rock was formed by buried coals self-ignition [36].

Shi is one of my teachers.

10. Line 89: Detailed “Concavisporites”

Response: Have done

11. Line 140: Delete “neutral”

Response: Have done

12. Line 142: Delete “Ph”

Response: Have done

13. Line 247-247: About the original of Chlorite

Response:  Although it cannot be excluded that some of the chlorite is derived from the transformation. The similar temporal evolution of kaolinite and chlorite suggest a common source.

14. Supply references

Response: Have done

Thanks for the reviewer’s recommendation, we have read the eight articles, and list five of them as references.

 

55. KORASIDIS, V.A.; WALLACE, M.W.; TOSOLINI, A.P.; HILL, R.S. THE ORIGIN OF FLORAL LAGERSTÄTTEN IN COALS. PALAIOS. 2020, 35, 22-36

77. Dai, S.; Hower, J.C.; Finkelman, R.B.; Graham, I.T.; French, D.; Ward, C.R.; Eskenazy, G.; Wei, Q.; Zhao, L. Organic associations of non-mineral elements in coal: A review. INT J COAL GEOL. 2020, 218, 103347

78. Karayigit, A.I.; Bircan, C.; Oskay, R.G.; Türkmen, O.; Querol, X. The geology, mineralogy, petrography, and geochemistry of the Miocene Dursunbey coal within fluvio-lacustrine deposits, Balıkesir (Western Turkey). INT J COAL GEOL. 2020, 228, 103548

79. Çelik, Y.; Karayigit, A.I.; Oskay, R.G.; Kayseri-Özer, M.S.; Christanis, K.; Hower, J.C.; Querol, X. A multidisciplinary study and palaeoenvironmental interpretation of middle Miocene Keles lignite (Harmancık Basin, NW Turkey), with emphasis on syngenetic zeolite formation. INT J COAL GEOL. 2021, 237 ,103691

84. Dai, S.; Bechtel, A.; Eble, C.F.; Flores, R.M.; French, D.; Graham, I.T.; Hood, M.M.; Hower, J.C.; Korasidis, V.A.; Moore, T.A.; Püttmann, W.; Wei, Q.; Zhao, L.; O'Keefe, J.M.K. Recognition of peat depositional environments in coal: A review. INT J COAL GEOL. 2020, 219, 103383

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has been changed, but really improved are just some figures and Table 1. BTW, using the data from Table 1, I found that Nb/Y-Zr/TiO2 diagram (Winchester and Floyd, 1977) indicates a distinct change of the sediment source from a common andesite-dacite to trachyandesite from Early to Middle Jurassic. It suggests that the Middle Jurassic sedimentation might be influenced by some alkaline volcanism in the region. All the element ratios used in this study might change correspondingly. I guess the authors may have the REE data (not present in Table 1) that can help recognizing changes in the provenance in more detail.

Both language and logic of reasoning are still very low. More comments may be found in the attached pdf file. So, I recommend rejection again.

Comments for author File: Comments.pdf

Author Response

We gratefully thank the reviewer for your time spend making the constructive remarks and useful suggestions, which has significantly raised the quality of the manuscript and has enable us to improve the manuscript. Each suggested revision and comment, brought forward by the reviewer was accurately incorporated and considered. All corrections are highlighted by red in the revised manuscript for tracking easily.

 

Point 1: About REE data and provenance

1. Response 1: Thanks for the reviewer’s suggestion. Indeed, it will be more convincing if we get a comparative assessment on provenance. The REE data and analysis have been added in the revised manuscript. We also have tried our best to discuss the provenance. However, due to the manuscript focused on the palaeoclimate and redox conditions change, we just identify the source rock and tectonic setting

according to the trace elements and rare earth elements. The further study should need detrital zircon U–Pb geochronology analysis.

 

The concentrations of trace elements in sediments are mainly controlled by terrigenous and/or sedimentary processes, diagenesis processes and some unknown factors[54]. Multivariate statistical method like cluster analysis was applied to distinguish these complex effects, factors and processes. The cluster analysis of the trace elements showed that 22 trace elements can be classified into 3 categories based on the cluster analysis (Figure 3), which could be applied to demonstrate the similarities and differences of elements [55, 56].

The first group (a) is mainly high-field-strength elements, including Zr, Th, Hf, Ta, and Nb, indicating the influence of terrigenous matter[57]. Group (b) includes Li, Ga, Sc, V, Cu, Co and Cr, and group (c) includes Ba, Sr, Rb, Zn, W, Cs, and Be.

 

Figure 3 Cluster analysis of trace elements

The total rare earth elements (∑REE) in Badaowan Formation show significant variability from 78-322 ppm (average = 155 ppm). The range of ∑REE from Sangonghe Formation is 102-173 ppm, with and average value of 128 ppm. In Xishanyao Formation, the ∑REE values varying between 123 ppm and 147 ppm, with an average value of 132 ppm. The average REE composition of the three formations are not much different in normalized concentrations. From the similarity in pattern they appear that the sediment sources remained constant during the period of deposition, although relative contributions may have varied [58]

The upper continental crust (UCC)-normalized REEs and trace elements distribution patterns of the Early-Middle Jurassic in the Yili Basin are presented in Figure 4. The UCC-normalized REES pattern in Badaowan Formation and Xishanyao Formation exhibit positive Eu anomalies.

 

Figure 4 UCC-normalized trace elements and REEs of samples from the the Su’asugou section in Yili Basin, NW China. UCC-normalization values are from Taylor and McLennan (1985) [59].

5.1.Provenance

To study the provenance of the study area, the property of the provenance was ana-lyzed based on the discrimination diagram of Zr/Sc versus Th/Sc (Figure 4A). It shows that the source itself from which the sediment has been derived has undergone recycling and sorting resulting in concentration of zircons during transport [58, 62] The discrimina-tion diagram of Hf versus La/Th was applied [63]. As is shown in Figure 4B, the composi-tion of the Early-Middle Jurassic in the Yili Basin was mainly acidic arc source. Data from most samples fall within the region of sedimentary rock and the intersectional region of alkaline basalt and sedimentary rock, apart from a few number of samples that fall within the region of continent tholeiitic basalts (Figure 4C). Diagram of La-Th-Sc shows that most samples are located in the continental island arc (Figure 4D).

Huang (2017) confirmed that the South Tianshan oceanic crust beneath the Yili–Central Tianshan block from the Late Devonian to late Carboniferous (380–310 Ma). and final amalgamation resulted in the uplift and denudation of the southern Yili–Central Tianshan block and (U)HP metamorphic belt along the northern margin of the South Tianshan orogenic belt [29]. Therefore, combined with previous geochemical features of fine-grained samples from the section, it can be concluded that the sedimentary rocks in the Yili Basin during the Early-Middle Jurassic may be derived from the Carboniferous rocks, and the tectonic setting of the source area could be referred to as the continental is-land arc and active continental margin.

Figure 5 Diagrams of the source rock compositions: (A) Zr/Sc versus Th/Sc plot; (B) Hf versus La/Th plot; (C) ∑REE versus La/Yb plot (modified from Liu et al., 2016) [64];(D) Tectonic discrimination plot of La–Th–Sc; a = oceanic island arc; b = continental island arc; c = active continental margin; d = passive margin [65].

 

Specific comments:

2. Line 22: Insert space

Response: Have done

 

3. Line 28: Modified “factors”

Response: factors (palaeoclimatic , depositional conditions, and palaeovegetation)

 

4. Line 29: productivity of ?

Response: productivity of peat-forming

 

5. Line 35: Insert space

Response: Have done

 

6. Line 37: Insert space

Response: Have done

 

7. Line 38: Insert space

Response: Have done

 

8. Line 39: Insert space

Response: Have done

 

9. Line 65: Modified the sentence “The Yili Basin is a composite intermontant basin evolved from the middle Tianshan microcontinent [27, 31-33]”

Response: The Yili Basin is a composite intermontant basin [37-40].

 

10. Line 70: Both terrigenous and clastic are sedimentary.

Response: delete “clastic”

 

11. Line 72: Insert space

Response: Have done

 

12. Line 73: Insert space

Response: Have done

 

• Line 75: Modified the sentence “ The Lower Jurassic is mainly composed of braided river delta, which is subdivided into the Badaowan Formation (Fm.) (SaJ1b) and Sangonghe Formation (Fm.) (SaJ1s).”

Response: The Lower Jurassic is subdivided into the Badaowan Formation (Fm.) (SaJ1b) and Sangonghe Formation (Fm.) (SaJ1s), and mainly composed of braided river delta.

 

• Line 82: Modified “20m”

Response: 20m in total

 

• Line 83: Insert space

Response: Have done

 

• Line 84: Insert space

Response: Have done

 

• Line 85-89: reference is needed

Response: Have done

The boundary of Sangonghe Fm. and Xishanyao Fm. is confirmed by the boundary between red mudstone and coarse-grained sandstone, which can be seen in the section [44-47].

 

• Line 90: DeleteInsert “the features of”

Response: Have done

 

• Figure 2: What generally means color in this column? Is this also a red burnt rock?

Response: The color in the column is the sedimentary color observed in outcrop. Two types of red strata deposited in the studied section. One is the red siltstone in the Sangonghe Formation, the other is the red burnt rock (coal essentially) in the Xishanyao Formation. In Figure 2, the red in the Xishanyao Formation is darker than Sangonghe Formation to distinguish.

 

• Line 98: Rephrase sentence “Detail of stratigraphic and field photographs across the Su’asugou section.”

Response: The stratigraphy and outcrop photographs of the Su’asugou section in Yili Basin.

 

• Line 72: Rephrase sentence “ using petrographic thin sections investigate sedimentary fabric and observe clay mineral assemblages”

Response: respecitively, using petrographic thin sections, fro investigating sedimentary fabric and observing clay mineral assemblages.

 

• Line 137: Insert space

Response: Have done

 

• Line 140-142: What does it mean?

Response: The value is used for calculating the enrichment.

 

• Line 143-148: Modified the method of pollen analysis

Response: The palynology samples were subjected to KOH (10%) for 10 min at 80°C and acetol-ysis treatment for 3 min at 90°C, following standard pollen preparation techniques [53]. Microscope slides were prepared from the residue and mounted in glycerol. A Zeiss light microscope at 400 and 1000x magnification was used for the identification of palynofloral.

 

• Line 152: Delete “.”

Response: Have done

 

• Corrected the Table 1

Response: Have done

Table 1. Trace elements and rare earth elements contents (ppm) of samples derived from the Su’asugou section in Yili Basin, NW China.

Sample	Li	Be		Sc		V		Cr		Co		Ni		Cu		Zn		Ga	Rb		Sr		Ta	Th
SaJ1b-2	53	2.3		16.		133		77		12		32		41		138		19	106		75		0.94	10
SaJ1b-3	129	2.7		22		117		59		3.9		27		24		118		31	112		79		1.5	14
SaJ1b-6	36	3.3		14		105		60		21		24		27		121		22	141		66		1.2	11
SaJ1b-7	44	3.2		16		92		50		9.5		20		38		186		25	148		90		1.5	13
SaJ1b-11	20	1.9		11		66		27		10		16		21		177		16	135		69		1.5	12
SaJ1b-12	48	1.9		18		130		82		15		44		43		105		20	95		74		0.71	9.9
SaJ1b-14	55	2.1		19		151		87		18		54		46		111		23	107		75		0.74	11
SaJ1b-18	65	2.3		21		163		92		19		55		54		124		25	113		83		0.79	11
SaJ1b-21	11	0.83		5.		41		27		5.8		8.7		10		29		9.4	70		40		0.49	5.8
SaJ1b-24	10	0.77		3.5		31		20		4.5		7.9		12		22		8.2	59		43		0.39	5.0
SaJ1b-25	17	0.97		5.0		45		19		9.6		9.8		15		40		8.9	57		37		0.41	5.7
SaJ1s-2	34	2.3		14		102		83		13		33		34		60		19	115		49		0.95	12
SaJ1s-3	42	1.6		12		82		63		6.3		18		30		80		18	90		94		1.0	10
SaJ1s-4	31	1.9		20		144		92		20		33		56		105		19	70		128		0.78	7.4
SaJ1s-5	12	0.85		6.8		47		37		9.6		20		11		59		12	85		35		0.66	6.9
SaJ1s-6	20	0.49		8.8		73		57		1.6		6.2		19		27		15	18		19		1.8	14
SaJ2x-3	32	0.65		11		94		67		1.8		7.8		25		30		21	28		32		2.2	19
SaJ2x-8	64	1.03		13		108		70		2.4		12		21		31		27	45		38		2.2	17
SaJ2x-12	56	0.76		11		90		70		2.4		12		16		28		22	33		29		2.1	16
SaJ2x-13	11	1.5		8.7		59		57		4.6		13		14		72		13	33		56		1.1	9.2
SaJ2x-15	9	1.8		10		63		77		5.6		14		19		84		15	41		138		1.2	12
	Lu	U		W		Zr		Mo		Nb		Cs		Ba		Hf		La	Ce		Pr		Nd	Yb
SaJ1b-2	0.53	4.5		19		253		0.76		14		12		426		6.4		28	61		7.1		27	3.2
SaJ1b-3	0.70	4.0		23		407		0.79		20		18		318		10		21	35		3.9		13	4.2
SaJ1b-6	0.54	3.1		11		339		0.78		17		17		462		8.1		34	89		7.6		29	3.4
SaJ1b-7	0.87	4.2		18		461		0.66		23		15		786		10		51	133		15.3		64	5.6
SaJ1b-11	0.77	5.0		13		593		4.8		24		7.1		799		13		42	90		10		41	4.8
SaJ1b-12	0.42	3.5		13		151		1.7		9.8		8.3		337		4.3		27	55		6.6		26	2.6
SaJ1b-14	0.47	3.4		20		162		1.6		10		9.8		350		4.4		30	64		7.4		29	2.9
SaJ1b-18	0.5	3.5		12		165		1.1		10		10		350		4.7		29	63		7.5		28	3.0
SaJ1b-21	0.18	1.7		10		105		0.49		6.1		2.3		430		2.9		16	33		3.9		14	1.2
SaJ1b-24	0.15	1.3		9.7		85		0.61		4.5		1.6		445		2.3		19	43		4.7		17	1.0
SaJ1b-25	0.33	1.5		8.8		109		0.44		4.9		1.8		351		3.2		18	41		4.5		17	2.0
SaJ1s-2	0.5	6.2		5.0		288		1.9		13		10		386		7.7		35	71		8.1		31	3.2
SaJ1s-3	0.35	3.9		9.9		217		2.4		14		6.9		410		6.0		24	52		5.8		22	2.3
SaJ1s-4	0.51	2.5		21		180		1.7		11		4.4		475		5.0		25	55		6.6		26	2.9
SaJ1s-5	0.29	1.6		1.1		127		0.7		8.5		2.7		435		3.2		22	41		4.7		18	1.7
SaJ1s-6	0.51	3.9		3.6		736		1.3		23		1.5		69		18		20	41		4.7		16	3.2
SaJ2x-3	0.57	4.7		4.2		734		1.6		27		2.4		257		18		27	57		6.3		22	3.6
SaJ2x-8	0.51	4.9		6.2		459		1.4		28		4.7		156		12		28	55		6.1		21	3.2
SaJ2x-12	0.55	4.6		7.1		701		1.2		27		3.5		116		17		26	50		5.6		19	3.4
SaJ2x-13	0.38	2.7		3.0		388		0.78		19		6.6		253		9.8		24	53		5.9		21	2.3
SaJ2x-15	0.47	3.4		3.1		667		1.2		21		8.3		241		16		33	61		6.6		23	2.9
	Sm		Eu		Gd		Tb		Dy		Ho		Er		Tm		∑REE	Sr/Cu		V/(V+Ni)		U/Th	MoEF	VEF
SaJ1b-2	5.6		1.4		4.9		0.82		4.9		1.1		3.2		0.48		150	1.8		0.80		0.43	0.46	1.14
SaJ1b-3	3.2		0.91		3.9		0.87		6.2		1.4		4.3		0.65		101	3.3		0.81		0.28	0.34	0.71
SaJ1b-6	5.8		1.2		5.3		0.87		5.7		1.2		3.5		0.52		188	2.4		0.81		0.26	0.49	0.92
SaJ1b-7	14.		2.8		12		1.8		10		2.0		5.8		0.89		322	2.3		0.82		0.31	0.37	0.72
SaJ1b-11	8.1		1.7		6.8		1.2		7.3		1.6		4.6		0.75		223	3.2		0.80		0.39	3.57	0.69
SaJ1b-12	5.3		1.3		4.6		0.76		4.5		0.93		2.7		0.41		139	1.7		0.75		0.35	0.97	1.07
SaJ1b-14	5.7		1.2		5.1		0.79		4.9		1.0		3.0		0.46		156	1.6		0.73		0.31	0.84	1.14
SaJ1b-18	5.8		1.2		4.8		0.80		4.9		1.0		3.0		0.46		155	1.5		0.75		0.30	0.54	1.17
SaJ1b-21	2.6		0.6		1.9		0.33		1.9		0.40		1.2		0.18		79	3.8		0.82		0.30	0.57	0.67
SaJ1b-24	3.3		0.73		2.4		0.37		2.4		0.40		1.0		0.16		97	3.5		0.80		0.25	0.69	0.28
SaJ1b-25	3.6		0.84		3.3		0.52		3.1		0.68		2.0		0.30		99	2.5		0.82		0.25	0.50	0.71
SaJ1s-2	6.1		1.4		5.3		0.83		5.1		1.0		3.0		0.48		173	1.4		0.76		0.48	1.22	0.93
SaJ1s-3	4.2		0.8		3.7		0.57		3.7		0.79		2.3		0.35		124	3.1		0.82		0.40	1.59	0.76
SaJ1s-4	5.8		1.5		5.2		0.81		4.8		1.0		2.9		0.45		139	2.3		0.81		0.34	0.99	1.2
SaJ1s-5	3.4		0.78		3.4		0.55		3.2		0.66		1.9		0.26		103	3.2		0.69		0.22	0.65	0.58
SaJ1s-6	3.2		0.57		3.2		0.56		3.9		0.89		2.8		0.48		103	1.0		0.92		0.28	1.45	1.17
SaJ2x-3	4.3		0.75		3.9		0.72		4.8		1.02		3.3		0.51		136	1.3		0.92		0.24	1.27	1.08
SaJ2x-8	4.0		0.83		3.6		0.63		4.4		0.99		2.9		0.46		133	1.8		0.90		0.28	2.91	3.12
SaJ2x-12	3.8		0.69		3.6		0.62		4.3		0.97		3.1		0.48		123	1.8		0.88		0.28	1.94	1.99
SaJ2x-13	4.4		1.1		3.6		0.64		3.9		0.83		2.4		0.37		126	2.3		0.79		0.47	0.75	1.53
SaJ2x-15	4.8		1.1		4.1		0.68		4.4		0.94		2.9		0.45		148	4.1		0.84		0.73	1.07	0.56

 

• Table 2: Delete smectit

Response: Have done

 

• Line 212: Insert space

Response: Have done

 

• Line 224: Insert space

Response: Have done

 

• Line 226: Insert space

Response: Have done

 

• Line 228: Rephrase sentence “the averages of V_EF continue to increase”

Response: the averages of V_EF keep increasing across the three formations.

 

• Line 234: 3.57 and 2.91 are much lower than 100 and 1000, aren't they?

Response: Yes, you are right, 3.57 and 2.91 are much lower than 100 and 1000. However, we discuss here just for the three formations in the manuscript. The value of Mo_EF is relatively higher than the other two formations.

 

• Line 240: Insert space

Response: Have done

 

• Line 241: I do not see any coal, burnt rock and red fine sandstone in Fig. 4.

Response: The correct figure is Figure 6 ,we have renumbered all the figures.

 

• Line 243: Insert space

Response: Have done

 

• Line 245: Insert space

Response: Have done

 

• 1: I do not see logic in this text

Response: Based on the geochemical data, the redox condition in the Yili Basin during the Early-Middle Jurassic is dysoxic. However, sedimentary features show difference. Compared with the coal in the Badaowan Formation and burnt rock (coal essentially) in the Xishanyao Formation, the red siltstone in the Sangonghe Formation shows the more oxic conditon.The similar red beds and the redox conditions have been confimed by many researchers (Wang et al., 2005; Neugebauer et al., 2017; Liu et al., 2019; Al Jyboury et al., 2020; Lu et al., 2020).Thus, combined with geochemical characteristics and sedimentary features, the sediments in the Sangonghe Formation deposited under relatively more oxic condition.

In a warm–humid palaeoclimate, the rise of the lake level hinders the oxygen circulation in the lake water, resulting in an anoxic sedimentary environment at the bottom of the lake (Zhang et al., 2020; Ma et al., 2016; Smith et al., 2014). Hence, such a change in redox conditions may have been related to the palaeoclimate fluctuations.

 

• Line 258: Insert space

Response: Have done

 

• Line 260: Insert space

Response: Have done

 

• Line 261: Insert space

Response: Have done

 

• Line 262-264: Sr/Cu and K/I also depends on source rocks.

Response: With the climate becoming humid and warm, Sr in the sediment leaches out because of more precipitation and strong weathering, which reduces in the Sr/Cu ratio; with the climate becoming dry and cold, more Sr remains in the sediments due to less precipitation and weak weathering, which leads to increase the Sr/Cu ratio [83, 84] .

In many cases, illtisation of kaolinite with depth is generally progressive [92, 93]. As is shown in Figure 7, The kaolinite decreasing is abrupt, rather indicating a palaeoclimate control [94]. Hence, we suggest that in the studied section the influence of burial diagenesis on the clay mineral assemblages is negligible, the K/I is a reliable proxy to inferred humidity/aridity changes.

 

• Line 271: Delete sentence “Through XRD diagrams, the sample from the Sangonghe Fm. has more kaolinite”

Response: Have done

 

• Line 272: I don't see it in Fig. 4

Response: The dark blue part is I/S, we have enlarged the legend.

 

• Line 275: Insert space

Response: Have done

 

• Line 281: Insert space

Response: Have done

 

• Line 282: Where is I/S in the Fig. 4 diagram?

Response: The dark blue part is I/S, we have enlarged the legend.

 

• Line 284: Is it logical? From the Early Jurassic towards the Middle Jurassic, which is characterized by a strong decreased content of I/S, though kaolinite remains the dominant clay mineral. This indicates a change from the semi-arid climate to the humid-subtropical climate [91].

Response: Chamley (1989) and Thirty (2000) confirmed that I/S mixed layers were associated with hot, semi-arid to arid conditions while kaolinite was related to humid conditions. In the studied section, the decreasing of the I/S shows the drought of palaeoclimate weaken. However, the kaolinite remians the dominant clay mineral. Hence, the palaeoclimate characterized by fluctuation with semi-arid to humid-subtropical.

 

• Line 304: peat-forming strata

Response: Change peat-forming strata to peat accumulation.

 

• Line 310: Insert space

Response: Have done

 

• Line 317: Insert space

Response: Have done

 

• Line 322: Insert space

Response: Have done

 

• Line 332: However, you are reporting the thick red burnt strata in the Xishanyao Fm. (Fig. 2).

Response: Two types of red strata in the studied section. The red beds in this sentence is the red siltstone in the Sangonghe Formation. We have rephrased the sentence to make it clearer.

 

• Line 333: Insert space

Response: Have done

 

• Line 339: Add “.”

Response: Have done

 

• Line 346: Insert space

Response: Have done

 

• Line 348: Insert space

Response: Have done

 

• Line 356: Insert space

Response: Have done

 

• Line 359: samples were determined?

Response: We have rephrased the sentence.

Fine-grained samples from the Early-Middle Jurassic sediments in Yili Basin were analyzed to infer the palaeoclimate changes and redox conditions during their sedimentation.

Author Response File: Author Response.pdf

Reviewer 4 Report

The authors did most of suggested corrections. But some points (e.g. palynomorphs names in text) in the MS need to be corrected by the authors. I added note in the attacted MS. Please follow them carefully. 

Comments for author File: Comments.pdf

Author Response

We gratefully thank the reviewer for your time spend making the constructive remarks and useful suggestions, which has significantly raised the quality of the manuscript and has enable us to improve the manuscript. Each suggested revision and comment, brought forward by the reviewers was accurately incorporated and considered. All corrections are highlighted by red in the revised manuscript for tracking easily.

Point 1: Palynomorphs names in text) in the MS need to be corrected

Response 1: We are very sorry for the mistakes in the palynomorphs names in the manuscript. We have revised the incorrect names and cited related literature.

4.3. Palynological data

Palynological data is an important source of quantitative terrestrial palaeoclimate data. Deng (2017) discussed the climate change based on the plant fosslis from the Lower Jurassic coal-bearing Hongqi Formation in the Xilinhot Basin [53]. Ptilophyllum is usually considerated as an important indicator of hot and relative arid environments [90, 91].

The palynofloral assemblage from the study area show that the Badaowan Fm. was dominated by Gymnospermae and very few fern spores. In terms of the composition of genus and species, most of the known species have been limited distribution in the Jurassic. Only a small number of them have been reported from the Upper Triassic as the lowermost appearance [60,61]. Therefore, there is no doubt that the strata belong to the Jurassic age. The main palynomorphs found in Sangonghe Fm. are similar to the Badaowan Fm., while few are differently (Table 3).

Table 3. List of the palynological data identified from the Su’asugou section in Yili Basin, NW China.

Formation	Sample Number	Palynologica data
Sangonghe Formation	SaJ1s-1	Chasmatosporites elegans, Vittatina sp., Striatoabieites multistriatus, Piceites arxanensis, Quadraeculina limbata, Pinuspollenites spp., Podocarpidites arxanensis, non-striate bisaccate
Badaowan Formation	SaJ1b-25	Dictophyllidites mortoni, Densoisporites sp., Cycadopites sp., Chasmatosporites elegans, Concavisporites toralis, Pseudopicea sp., Piceites arxanensis, Pinuspollenites spp., Piceaepollenites sp., Podocarpidites multesimus, non-striate bisaccate
	SaJ1b-14	Cyathidites minor, Concavisporites bohemiensis, Concavisporites toralis, Osmundacidites wellmani, Aratrisporites granulatus, Chadmatosporites elegans, Taeniaesporites pellucidus, Pseudopicea sp., Piceites arxanensis, Pinuspollenites spp., Piceaepollenites sp., Podocarpidites multesimus, Podocarpidites arxanensis, non-striate bisaccate
	SaJ1b-12	Concavisporites toralis, Aratrisporites granulatus, Pseudopicea sp., Vitreisporites sp., Klausipollenites sp., Pinuspollenites spp., Podocarpidites multesimus, non-striate bisaccate
	SaJ1b-7	Stereisporites sp., Vittatina sp., Protohaploxypinus limpidus, Striatoabieites multistriatus, Gardenasporites sp., Pseudopicea sp., Vitreisporites sp., Piceites arxanensis, Parvisaccites sp., Pinuspollenites spp., Podocarpidites multesimus, non-striate bisaccate
	SaJ1b-6	Podocarpidites sp. non-striate bisaccate
	SaJ1b-3	Osmundacidites wellmani, Perinopollenites sp., Pseudopicea sp.

 

 

Specific comments:

1. Line 35: Insert space

Response: Have done

 

2. Line 49-52: Cited related literature in the sentence “Furthermore, mineralogical and maceral composition of coal seams along with sedimentological palynological and stable isotope data could provide essential data for palaeoclimatic and depositional conditions, and palaeovegetation during peat-accumulation.”

Response: Furthermore, mineralogical and maceral composition of coal seams along with sedi-mentological palynological and stable isotope data could provide essential data for palaeoclimatic and depositional conditions, and palaeovegetation during peat-accumulation [26-31].

 

3. Line 91: Change “” to “genus”

Response: Have done

 

4. Line 165: Modified Table 1

Response: Have done

Table 1. Trace elements and rare earth elements contents (ppm) of samples derived from the Su’asugou section in Yili Basin, NW China.

Sample	Li	Be		Sc		V		Cr		Co		Ni		Cu		Zn		Ga	Rb		Sr		Ta	Th
SaJ1b-2	53	2.3		16.		133		77		12		32		41		138		19	106		75		0.94	10
SaJ1b-3	129	2.7		22		117		59		3.9		27		24		118		31	112		79		1.5	14
SaJ1b-6	36	3.3		14		105		60		21		24		27		121		22	141		66		1.2	11
SaJ1b-7	44	3.2		16		92		50		9.5		20		38		186		25	148		90		1.5	13
SaJ1b-11	20	1.9		11		66		27		10		16		21		177		16	135		69		1.5	12
SaJ1b-12	48	1.9		18		130		82		15		44		43		105		20	95		74		0.71	9.9
SaJ1b-14	55	2.1		19		151		87		18		54		46		111		23	107		75		0.74	11
SaJ1b-18	65	2.3		21		163		92		19		55		54		124		25	113		83		0.79	11
SaJ1b-21	11	0.83		5.		41		27		5.8		8.7		10		29		9.4	70		40		0.49	5.8
SaJ1b-24	10	0.77		3.5		31		20		4.5		7.9		12		22		8.2	59		43		0.39	5.0
SaJ1b-25	17	0.97		5.0		45		19		9.6		9.8		15		40		8.9	57		37		0.41	5.7
SaJ1s-2	34	2.3		14		102		83		13		33		34		60		19	115		49		0.95	12
SaJ1s-3	42	1.6		12		82		63		6.3		18		30		80		18	90		94		1.0	10
SaJ1s-4	31	1.9		20		144		92		20		33		56		105		19	70		128		0.78	7.4
SaJ1s-5	12	0.85		6.8		47		37		9.6		20		11		59		12	85		35		0.66	6.9
SaJ1s-6	20	0.49		8.8		73		57		1.6		6.2		19		27		15	18		19		1.8	14
SaJ2x-3	32	0.65		11		94		67		1.8		7.8		25		30		21	28		32		2.2	19
SaJ2x-8	64	1.03		13		108		70		2.4		12		21		31		27	45		38		2.2	17
SaJ2x-12	56	0.76		11		90		70		2.4		12		16		28		22	33		29		2.1	16
SaJ2x-13	11	1.5		8.7		59		57		4.6		13		14		72		13	33		56		1.1	9.2
SaJ2x-15	9	1.8		10		63		77		5.6		14		19		84		15	41		138		1.2	12
	Lu	U		W		Zr		Mo		Nb		Cs		Ba		Hf		La	Ce		Pr		Nd	Yb
SaJ1b-2	0.53	4.5		19		253		0.76		14		12		426		6.4		28	61		7.1		27	3.2
SaJ1b-3	0.70	4.0		23		407		0.79		20		18		318		10		21	35		3.9		13	4.2
SaJ1b-6	0.54	3.1		11		339		0.78		17		17		462		8.1		34	89		7.6		29	3.4
SaJ1b-7	0.87	4.2		18		461		0.66		23		15		786		10		51	133		15.3		64	5.6
SaJ1b-11	0.77	5.0		13		593		4.8		24		7.1		799		13		42	90		10		41	4.8
SaJ1b-12	0.42	3.5		13		151		1.7		9.8		8.3		337		4.3		27	55		6.6		26	2.6
SaJ1b-14	0.47	3.4		20		162		1.6		10		9.8		350		4.4		30	64		7.4		29	2.9
SaJ1b-18	0.5	3.5		12		165		1.1		10		10		350		4.7		29	63		7.5		28	3.0
SaJ1b-21	0.18	1.7		10		105		0.49		6.1		2.3		430		2.9		16	33		3.9		14	1.2
SaJ1b-24	0.15	1.3		9.7		85		0.61		4.5		1.6		445		2.3		19	43		4.7		17	1.0
SaJ1b-25	0.33	1.5		8.8		109		0.44		4.9		1.8		351		3.2		18	41		4.5		17	2.0
SaJ1s-2	0.5	6.2		5.0		288		1.9		13		10		386		7.7		35	71		8.1		31	3.2
SaJ1s-3	0.35	3.9		9.9		217		2.4		14		6.9		410		6.0		24	52		5.8		22	2.3
SaJ1s-4	0.51	2.5		21		180		1.7		11		4.4		475		5.0		25	55		6.6		26	2.9
SaJ1s-5	0.29	1.6		1.1		127		0.7		8.5		2.7		435		3.2		22	41		4.7		18	1.7
SaJ1s-6	0.51	3.9		3.6		736		1.3		23		1.5		69		18		20	41		4.7		16	3.2
SaJ2x-3	0.57	4.7		4.2		734		1.6		27		2.4		257		18		27	57		6.3		22	3.6
SaJ2x-8	0.51	4.9		6.2		459		1.4		28		4.7		156		12		28	55		6.1		21	3.2
SaJ2x-12	0.55	4.6		7.1		701		1.2		27		3.5		116		17		26	50		5.6		19	3.4
SaJ2x-13	0.38	2.7		3.0		388		0.78		19		6.6		253		9.8		24	53		5.9		21	2.3
SaJ2x-15	0.47	3.4		3.1		667		1.2		21		8.3		241		16		33	61		6.6		23	2.9
	Sm		Eu		Gd		Tb		Dy		Ho		Er		Tm		∑REE	Sr/Cu		V/(V+Ni)		U/Th	MoEF	VEF
SaJ1b-2	5.6		1.4		4.9		0.82		4.9		1.1		3.2		0.48		150	1.8		0.80		0.43	0.46	1.14
SaJ1b-3	3.2		0.91		3.9		0.87		6.2		1.4		4.3		0.65		101	3.3		0.81		0.28	0.34	0.71
SaJ1b-6	5.8		1.2		5.3		0.87		5.7		1.2		3.5		0.52		188	2.4		0.81		0.26	0.49	0.92
SaJ1b-7	14.		2.8		12		1.8		10		2.0		5.8		0.89		322	2.3		0.82		0.31	0.37	0.72
SaJ1b-11	8.1		1.7		6.8		1.2		7.3		1.6		4.6		0.75		223	3.2		0.80		0.39	3.57	0.69
SaJ1b-12	5.3		1.3		4.6		0.76		4.5		0.93		2.7		0.41		139	1.7		0.75		0.35	0.97	1.07
SaJ1b-14	5.7		1.2		5.1		0.79		4.9		1.0		3.0		0.46		156	1.6		0.73		0.31	0.84	1.14
SaJ1b-18	5.8		1.2		4.8		0.80		4.9		1.0		3.0		0.46		155	1.5		0.75		0.30	0.54	1.17
SaJ1b-21	2.6		0.6		1.9		0.33		1.9		0.40		1.2		0.18		79	3.8		0.82		0.30	0.57	0.67
SaJ1b-24	3.3		0.73		2.4		0.37		2.4		0.40		1.0		0.16		97	3.5		0.80		0.25	0.69	0.28
SaJ1b-25	3.6		0.84		3.3		0.52		3.1		0.68		2.0		0.30		99	2.5		0.82		0.25	0.50	0.71
SaJ1s-2	6.1		1.4		5.3		0.83		5.1		1.0		3.0		0.48		173	1.4		0.76		0.48	1.22	0.93
SaJ1s-3	4.2		0.8		3.7		0.57		3.7		0.79		2.3		0.35		124	3.1		0.82		0.40	1.59	0.76
SaJ1s-4	5.8		1.5		5.2		0.81		4.8		1.0		2.9		0.45		139	2.3		0.81		0.34	0.99	1.2
SaJ1s-5	3.4		0.78		3.4		0.55		3.2		0.66		1.9		0.26		103	3.2		0.69		0.22	0.65	0.58
SaJ1s-6	3.2		0.57		3.2		0.56		3.9		0.89		2.8		0.48		103	1.0		0.92		0.28	1.45	1.17
SaJ2x-3	4.3		0.75		3.9		0.72		4.8		1.02		3.3		0.51		136	1.3		0.92		0.24	1.27	1.08
SaJ2x-8	4.0		0.83		3.6		0.63		4.4		0.99		2.9		0.46		133	1.8		0.90		0.28	2.91	3.12
SaJ2x-12	3.8		0.69		3.6		0.62		4.3		0.97		3.1		0.48		123	1.8		0.88		0.28	1.94	1.99
SaJ2x-13	4.4		1.1		3.6		0.64		3.9		0.83		2.4		0.37		126	2.3		0.79		0.47	0.75	1.53
SaJ2x-15	4.8		1.1		4.1		0.68		4.4		0.94		2.9		0.45		148	4.1		0.84		0.73	1.07	0.56

 

5. Line 317: Change “peat-formation” to “plants”

Response: Have done

 

6. Line 325: Delete “Meanwhile”

Response: Have done

 

7. Line 347: Delete “the”

Response: Have done

 

8. Line 348: Delete “more coal”

Response: Have done

 

9. Line 142: Delete “swamp”

Response: Have done

 

Author Response File: Author Response.pdf

Round 3

Reviewer 4 Report

Even though the MS improved quite well, there are some typo errors and some data (e.g., applied distance in the cluster analysis) should add into the text. I added several notes in the revised MS. The authors should them carefully. Overall, I believe that the MS could be sent to production after the suggested corrections done.

Comments for author File: Comments.pdf

Author Response

We would like to thank the reviewer once again for the professional comments. These comments are all valuable and very helpful for improving the manuscript, as well as the important guiding significance to our research. We have carefully considered the thoughtful suggestions and made correction. Revised portion are highlighted by red in the manuscript for tracking easily.

 

Specific comments:

1. Line 19-20: Delete “Here, Jurassic witnessed space entirely…sedimentation”

Response: Have done

 

2. Line 22: Delete “Samples”

Response: Have done

 

3. Line 22: Add “and palynological”

Response: Have done

 

4. Line 23: Move sentence “Additionally, combined with present study, the factors (palaeoclimatic, depositional conditions, and palaeovegatation) impact peat accumulation during the Early Jurassic Badaowan Formation and the Middle Jurassic Xishanyao Formation are investigated. Fine-grained sediments were col-lected from Su’asugou section in southern of Yili Basin, Northwest China.”

Response: Have done

 

5. Line 24: Delete “suggest”

Response: Have done

 

6. Line 26: Delete “indicate”

Response: Have done

 

7. Line 36: Delete “This”

Response: Have done

 

8. Line 56: Delete “This”

Response: Have done

 

9. Geological setting: Please, justify the paragraph

Response: Have done

The triangular-shaped Yili Basin is sandwhiched between the Junggar block and Central Tianshan block (Figure 1B, C) [35], and it widens into Kazakhstan and Kyrgyz-stan [36-38]. The Yili Basin represents the easternmost segment of the Kazakhstan–Yili microcontinent with a latitude of approximately 40◦N (Figure 1A, B) [33, 34, 37-40]. The sediment-source region mainly consists of Hercynian granite, Permo-Carboniferous intermediate and felsic igneous rocks, and pyroclastic rocks interbedded with carbonate layers. These units form the basement to the Yili Basin, which is infilled by Mesozoic conglomerate, sandstone and mudstone, and by Cenozoic clastic sediments [39,41]. During the Jurassic, the Yili Basin is a continental sedimentary with abundant coal reserves [38].

 

10. Line 76: Delete “Study”

Response: Have done

 

11. Line 80: Delete “black coal bed”

Response: Have done

 

12. Line 83: Delete “beds”

Response: Have done

 

13. Line 111: Delete “We examined”

Response: Have done

 

14. Line 112: Add “were examined”

Response: Have done

21 fine-grained samples from the section in the southern Yili Basin (Figure 1) were examined.

 

15. Line 112: Delete “respectively”

Response: Have done

 

16. Line 22: About “Taking account of various circumstances, location and transportation, the sampling interval of the studied samples was one sample for each layer, without accurate data.”

Response: The description of sampling interval, another reviewer asked us to provide before.

 

17. Line 119: Delete “(<2μm)”

Response: Have done

 

18. Line 157: Delete “like cluster analysis”

Response: Have done

 

19. Figure 3: please, provide distance and applied interval. For instance “pearson correlation coefficienies” or “Euclidean distance”

Response: Have done

The cluster analysis of the trace elements showed that 22 trace elements can be classified into 3 categories based on the Pearson correlation (Figure 3)

 

20. Line 239: Delete “To study”

Response: Have done

 

21. Line 244: Delete “source”

Response: Have done

 

22. Line 264: Delete “reconstruct”

Response: Have done

 

23. Line 265: Delete “because of their…that leads”

Response: Have done

 

24. Line 266: Delete “Here, we use”

Response: Have done

 

25. Line 264-267: Add “during deposition” and “were applied in order to”

Response: Have done

Redox-sensitive trace metals have been used extensively as geochemical proxies to infer the redox-status of sediments during deposition [50]. The authigenic enrichment of these metals in sediments is driven by the different solubility and/or affinity for particulates of the various redox states, which in turn can be related to the the redox status at the time of sediment deposition [51]. Trace element ratios V/(V+Ni), U/Th, V_EF and Mo_EF were applied in order to decipher the palaeoredox change (Figure 3).

 

26. Line 278: Delete “indicate”

Response: Have done

 

27. Line 285: Delete “long…recognized”

Response: Have done

 

28. Line 287: Delete “study”

Response: Have done

 

29. Line 290: Change “was dysoxic” to “dysoxic”

Response: Have done

 

30. Line 297: Delete “in”

Response: Have done

 

31. Line 299: Delete “in the exploration”

Response: Have done

 

32. Line 302: Delete “coal and burnt rock”

Response: Have done

 

33. Line 305: For the record, as far as I read from the literature, the Gercus Formation in the SE Turkey and NE Iraq are totally different story than self-ignited coal seam. Please, be careful!

Response: Yes, you are right. Here, we discuss redox condition of the red siltstone in the Sangonghe Formation, not the red burnt rock (self-ignited coal seam) in the Xishanyao Formation.

 

34. Line 314: Delete “climate”

Response: Have done

 

35. Line 319: Delete “Average”

Response: Have done

 

36. Line 321: Delete “has been used successfully”

Response: Have done

 

37. Line 327: Delete “the transformation”

Response: Have done

 

38. Line 334: Delete “study”

Response: Have done

 

39. Line 337-338: Delete “warm droughts”

Response: Have done

 

40. Line 345: About “the combustion metamorphic rocks” Did the author mean self-ignition of coal layers or pyrometamorphized coal-bearing sequence? If yes, please re-phrase this section.

Response: Thanks for the significant reminding. We did make incorrect description. The red beds mentioned here is the red siltstone in the Sangonghe Formation, and we have revised.

Drought also can be inferred from the red sandstone deposited (Figure 3), as the red siltstone in the Sangonghe Fm., which was confirmed as an indicator of arid climate conditions [97]

 

41. Line 348: Delete “indicates a”

Response: Have done

 

42. Line 358: Delete “matching”

Response: Have done

 

43. Line 361: Delete “our results”

Response: Have done

 

44. Line 365: Delete “carbon”

Response: Have done

 

45. Line 371: Delete “strata”

Response: Have done

 

46. Line 374: Delete “beds”

Response: Have done

 

47. Line 377: Delete “paleo-”

Response: Have done

 

48. Line 385: Delete “sediments rich in coal”

Response: Have done

 

49. Line 390: Delete “the coals both”

Response: Have done

 

50. Line 392: Delete “On the other side, climatic conditions”

Response: Have done

 

51. Line 395: Delete “was deposited in ”

Response: Have done

 

52. Line 396: Delete “under…of deposition”

Response: Have done

 

53. Line 395-396: About “French, K.L. et al. (2014)” This study focused on anoxic events in Torcian oceans. Please, keep in mind it!

Response: Thank you for this very insightful comment. We have corrected this to the applicable literature, and renumbered the references.

Dai (2020) suggested the organic matter deposition follow “dry-light model” and “wet-dark model” [110].

 

54. Line 403-405: About “Lu (2020)”. Be careful! Toarcian OAE was developed due to climate changes. Therefore, please re-phrase this sentence, since the authors focused on terrestrial environment.

Response: Thanks for the kindly reminding. Toarcian OAE is a global climate event during the Early Jurassic. Lu (2020) investigated organic carbon isotope composition (δ¹³C_org), weathering trends and geochemistry in Lower Jurassic lacustrine strata in the Qaidam Basin. The results show that the T-OAE was a period of intense warming and arid climate, expressed by the deposition of red beds, a hiatus in coal deposition, a sharp reduction in plant diversity, and a floristic turnover in palynoflora.

 

55. Line 411: Delete “transportation (supply)”

Response: Have done

 

56. Line 414: Delete “delta”

Response: Have done

 

57. Line 417: Delete “On the other side”

Response: Have done

 

58. Line 420: Delete “combine to result in peat swamps development, driving”

Response: Have done

 

59. Line 421: Delete “peat”

Response: Have done

 

60. Line 451: Delete “coal deposition”

Response: Have done

 

Author Response File: Author Response.pdf