the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 20 Jun 2024
Orbital-scale climate dynamics impacts on Gzhelian peatland wildfire activity in the Ordos Basin
Abstract. The Carboniferous, an important coal-forming period in geological history, was characterized by extensive vegetation and high oxygen levels. Numerous wildfire evidence suggests that high frequency of wildfire occurred at that time, specifically in peatlands. However, the control mechanisms for changes in wildfire activity in peatlands during this period are still not clearly understood. In this study, evidence from the Gzhelian in the Ordos Basin, such as the inertinite/vitrinite (I/V) ratio, indicated the existence of different frequencies of wildfire activity at that time. The CaO/MgO and CaO/MgO • Al2O3 climate indicators revealed that high-frequency wildfires mainly occur in warm and humid climates. Based on former age constraints, we deduced that orbital cycles (long eccentricity) controlled the climate influence on peatland wildfires during the Gzhelian. When eccentricity was high, abundant sunshine and frequent rainfall led to warmer and more humid peatlands. The latter environments were more favourable for vegetation development, leading to increased fuel loads, which in turn led to more frequent wildfires. Moreover, the Gzhelian global wildfire records, showed that evidence of wildfire during this period was mainly located in areas with abundant tropical vegetation, supporting the view that wildfire activity during this period was mainly controlled by the fuel loads. Although Hg could be produced by peatland wildfires, but our results show that Hg was mainly from frequent volcanic activity during this period.
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RC1: 'Comment on cp-2024-42', Anonymous Referee #1, 15 Jul 2024
The comment was uploaded in the form of a supplement: https://cp.copernicus.org/preprints/cp-2024-42/cp-2024-42-RC1-supplement.pdf
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AC1: 'Reply on RC1', Dawei Lv, 06 Sep 2024
Thank you very much for your comments on our manuscript. We have also identified many shortcomings and have made every effort to improve them. The detailed revisions have been added in the attachment. Once again, we sincerely appreciate your valuable suggestions.
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AC1: 'Reply on RC1', Dawei Lv, 06 Sep 2024
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RC2: 'Comment on cp-2024-42', Cortland Eble, 05 Aug 2024
This is an interesting paper that provides an explanation for wildfire occurrence in the Late Pennsylvanian. Most of my comments are grammatical in nature and can be easily addressed. One specific point that should be addressed is the age of peat deposits relative to eccentricity cycles. Most age dates of modern peatlands indicates that they are short-lived in a geological sense, with age dates of 8,000 to 10, 000 years being a common theme. I would ask the authors to explain more thoroughly how eccentricity cycles, which occur on a larger time-scale, effect the occurrence of charcoal in peat bodies that are much younger in duration. Alternatively, please provide some references that document peat accumulations that are much older (100,000 years +). Otherwise, I find the paper to be well-organized with good tables and illustrations. Please contact me directly if you have any questions regarding any of my comments in the marked-up pdf file.
Cortland Eble
University of Kentucky
ebe@uky.edu
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AC2: 'Reply on RC2', Dawei Lv, 06 Sep 2024
Thank you very much for your comments on our manuscript. We have also identified many shortcomings and have made every effort to improve them. The detailed revisions have been added in the attachment. Once again, we sincerely appreciate your valuable suggestions.
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AC2: 'Reply on RC2', Dawei Lv, 06 Sep 2024
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EC1: 'Comment on cp-2024-42', Gerilyn (Lynn) Soreghan, 07 Aug 2024
This manuscript is an interesting attempt to examine climate and fire relationships from a very ancient archive— the late Paleozoic. The manuscript is generally well organized, and methods are clear.
Although the concept anchoring this study, that is, the relationship among climate and orbital controls and fires, is certainly interesting, especially in Earth’s deep-time record, I’m concerned that there are too few data points to really examine this dataset robustly, and make the claims that the authors are making-- both in terms of assessing climate proxies, and in assessing possible orbital controls. I’m also concerned about the use of CaO/MgO ad Al2O3 as climate proxies, given research suggesting these oxides are overwhelmingly controlled by provenance. Additionally, I think that, to claim an orbital control, one needs to demonstrate a quantitative cyclostratigraphy, rather than base this on a visual comparison of curves, and the data set is not sufficiently large to conduct such a quantitative analysis. The latter is particularly compromised by the age control, which, although very good for such a deep-time interval, still harbors significant error (a duration that could range between 800,000 years and 4.6 My). The error is just too large to be able to make the claims of an eccentricity control.
Overall, I think the data set is not sufficiently robust to make the sorts of interpretations that the authors are suggesting. I consider the issues raised (both in my review, and in others) to be sufficiently serious to question whether any amount of revision could bring this dataset to a level that would justify publication. However, perhaps I am mistaken, so the authors should carefully consider the comments and decide whether the issues can be addressed. To continue the line of argument in the current version would require significantly more data, and quantitative analysis thereof. Unfortunately, given these concerns, I do not expect to encourage a revision.
Minor comments:
110— what is a “<20 top size” ? What are the units here?
141-142— To increase the comprehensive of the database, it would be good to also use “Virgilian wildfire” to capture North American incidences.
162— should be “Scotese”
167— Could a principal component analysis (PCA) to see how all of these variables co-relate shed additional insight?
Table 1— fix such that column labels are not truncated
214— typo; need extra space
223— The “Virgilian” is the (approximate) time equivalent to the Gzhelian and was/is widely used in North America, so if you want this to be a more comprehensive database consider using that search term as well.
285— noun needed (“organic and inorganic” what?)— maybe “matter”?
302-303— But, consider the volume of vegetation that is required to result in a given volume of peat (or— even more so— coal). Clearly there will be a greater concentration in the latter owing to this volume difference. Is that the point you are trying to make? I’m finding the reasoning in this paragraph difficult to follow; I think I understand your point, but it is a bit muddled in my reading.
320-321— I’m not sure what this means— the “…dipping of tonsteins by acid solutions.” Are you referring to the leaching of ton steins by organic acids released/related to the coals?
321-322— again, PCA might help?
326— unclear what is meant by “closing coals”
Fig 5— it would be easier to analyze the possible correlations by conducting multicomponent statistical analyses. Also, on this plot, each dot represents a coal sample from a correlative coal seam? Ie, are the labels on the left — “YG”— are those all discrete coal layers? Could you add a graphical stratigraphic log to help visualization of this?
If I am understanding correctly, you are suggesting that various curves here reflect the eccentricity curve, based on visual comparison. But to really be convincing, I think this would require a more quantitative analysis, and probably with many more data points (than the 20 here).
351— Although such metrics have been used to assess weathering and, by extension, climate, recent studies have called this into question owing to the strong (overriding) control of provenance on these oxides.
360— typo
377—The 1.9 Ma is not a depositional age, but I think you mean duration here, which means the units should be My. But that’s not quite correct, because you have not considered the error bars. Considering the errors on both dates, the duration could be as long as 4.6 My, or as brief as 0.8 My.
379-380— I do not think that a visual comparison, with so few data points, is sufficient to make this claim.
382— typo
Citation: https://doi.org/10.5194/cp-2024-42-EC1 -
AC3: 'Reply on EC1', Dawei Lv, 06 Sep 2024
Thank you very much for your comments on our manuscript. We have also identified many shortcomings and have made every effort to address them. The detailed revisions have been included in the attachment. I apologize for the delay in responding as I was engaged in fieldwork recently. Once again, we sincerely appreciate your valuable suggestions.
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AC3: 'Reply on EC1', Dawei Lv, 06 Sep 2024
Status: closed
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RC1: 'Comment on cp-2024-42', Anonymous Referee #1, 15 Jul 2024
The comment was uploaded in the form of a supplement: https://cp.copernicus.org/preprints/cp-2024-42/cp-2024-42-RC1-supplement.pdf
-
AC1: 'Reply on RC1', Dawei Lv, 06 Sep 2024
Thank you very much for your comments on our manuscript. We have also identified many shortcomings and have made every effort to improve them. The detailed revisions have been added in the attachment. Once again, we sincerely appreciate your valuable suggestions.
-
AC1: 'Reply on RC1', Dawei Lv, 06 Sep 2024
-
RC2: 'Comment on cp-2024-42', Cortland Eble, 05 Aug 2024
This is an interesting paper that provides an explanation for wildfire occurrence in the Late Pennsylvanian. Most of my comments are grammatical in nature and can be easily addressed. One specific point that should be addressed is the age of peat deposits relative to eccentricity cycles. Most age dates of modern peatlands indicates that they are short-lived in a geological sense, with age dates of 8,000 to 10, 000 years being a common theme. I would ask the authors to explain more thoroughly how eccentricity cycles, which occur on a larger time-scale, effect the occurrence of charcoal in peat bodies that are much younger in duration. Alternatively, please provide some references that document peat accumulations that are much older (100,000 years +). Otherwise, I find the paper to be well-organized with good tables and illustrations. Please contact me directly if you have any questions regarding any of my comments in the marked-up pdf file.
Cortland Eble
University of Kentucky
ebe@uky.edu
-
AC2: 'Reply on RC2', Dawei Lv, 06 Sep 2024
Thank you very much for your comments on our manuscript. We have also identified many shortcomings and have made every effort to improve them. The detailed revisions have been added in the attachment. Once again, we sincerely appreciate your valuable suggestions.
-
AC2: 'Reply on RC2', Dawei Lv, 06 Sep 2024
-
EC1: 'Comment on cp-2024-42', Gerilyn (Lynn) Soreghan, 07 Aug 2024
This manuscript is an interesting attempt to examine climate and fire relationships from a very ancient archive— the late Paleozoic. The manuscript is generally well organized, and methods are clear.
Although the concept anchoring this study, that is, the relationship among climate and orbital controls and fires, is certainly interesting, especially in Earth’s deep-time record, I’m concerned that there are too few data points to really examine this dataset robustly, and make the claims that the authors are making-- both in terms of assessing climate proxies, and in assessing possible orbital controls. I’m also concerned about the use of CaO/MgO ad Al2O3 as climate proxies, given research suggesting these oxides are overwhelmingly controlled by provenance. Additionally, I think that, to claim an orbital control, one needs to demonstrate a quantitative cyclostratigraphy, rather than base this on a visual comparison of curves, and the data set is not sufficiently large to conduct such a quantitative analysis. The latter is particularly compromised by the age control, which, although very good for such a deep-time interval, still harbors significant error (a duration that could range between 800,000 years and 4.6 My). The error is just too large to be able to make the claims of an eccentricity control.
Overall, I think the data set is not sufficiently robust to make the sorts of interpretations that the authors are suggesting. I consider the issues raised (both in my review, and in others) to be sufficiently serious to question whether any amount of revision could bring this dataset to a level that would justify publication. However, perhaps I am mistaken, so the authors should carefully consider the comments and decide whether the issues can be addressed. To continue the line of argument in the current version would require significantly more data, and quantitative analysis thereof. Unfortunately, given these concerns, I do not expect to encourage a revision.
Minor comments:
110— what is a “<20 top size” ? What are the units here?
141-142— To increase the comprehensive of the database, it would be good to also use “Virgilian wildfire” to capture North American incidences.
162— should be “Scotese”
167— Could a principal component analysis (PCA) to see how all of these variables co-relate shed additional insight?
Table 1— fix such that column labels are not truncated
214— typo; need extra space
223— The “Virgilian” is the (approximate) time equivalent to the Gzhelian and was/is widely used in North America, so if you want this to be a more comprehensive database consider using that search term as well.
285— noun needed (“organic and inorganic” what?)— maybe “matter”?
302-303— But, consider the volume of vegetation that is required to result in a given volume of peat (or— even more so— coal). Clearly there will be a greater concentration in the latter owing to this volume difference. Is that the point you are trying to make? I’m finding the reasoning in this paragraph difficult to follow; I think I understand your point, but it is a bit muddled in my reading.
320-321— I’m not sure what this means— the “…dipping of tonsteins by acid solutions.” Are you referring to the leaching of ton steins by organic acids released/related to the coals?
321-322— again, PCA might help?
326— unclear what is meant by “closing coals”
Fig 5— it would be easier to analyze the possible correlations by conducting multicomponent statistical analyses. Also, on this plot, each dot represents a coal sample from a correlative coal seam? Ie, are the labels on the left — “YG”— are those all discrete coal layers? Could you add a graphical stratigraphic log to help visualization of this?
If I am understanding correctly, you are suggesting that various curves here reflect the eccentricity curve, based on visual comparison. But to really be convincing, I think this would require a more quantitative analysis, and probably with many more data points (than the 20 here).
351— Although such metrics have been used to assess weathering and, by extension, climate, recent studies have called this into question owing to the strong (overriding) control of provenance on these oxides.
360— typo
377—The 1.9 Ma is not a depositional age, but I think you mean duration here, which means the units should be My. But that’s not quite correct, because you have not considered the error bars. Considering the errors on both dates, the duration could be as long as 4.6 My, or as brief as 0.8 My.
379-380— I do not think that a visual comparison, with so few data points, is sufficient to make this claim.
382— typo
Citation: https://doi.org/10.5194/cp-2024-42-EC1 -
AC3: 'Reply on EC1', Dawei Lv, 06 Sep 2024
Thank you very much for your comments on our manuscript. We have also identified many shortcomings and have made every effort to address them. The detailed revisions have been included in the attachment. I apologize for the delay in responding as I was engaged in fieldwork recently. Once again, we sincerely appreciate your valuable suggestions.
-
AC3: 'Reply on EC1', Dawei Lv, 06 Sep 2024
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