Modern Capabilities of Semi-Airborne UAV-TEM Technology on the Example of Studying the Geological Structure of the Uranium Paleovalley

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 The manuscript presents the results by a new generation of semi-airborne technology. It's an interesting topic. But the authors haven't write it properly. There are many trace of AI-generating, such as the abstract and conclusion section. 

1. The section 2 described the methodology, but not clearly. 

2. There isn't section 4. 

3. There are many writing errors and grammar errors.

Also, the figures' resolution aren't high enough to read clearly. When there are two or more subgraph in a figure, a), b) etc. need to be identified in the figure, such as Fig.6.

4.The keywords, unmanned aerial vehicles and UAV have the same meaning. Only one needs be kept. 

5.The format of  references is not correct. 2-7 et al, 10-14 et al, and so on. They should be 2-7, 10-14..  [], no reference number in it of line 69; The unit inf Fig.4 should be unified.

6.Fig.8 should be Fig.6. The order of figure should be continuous. 

7.In order to clearly show the geological background of the study area, the author needs to add a regional geological map and indicate the location information.

Comments on the Quality of English Language

Not good enough to be acceptable.

Author Response

The authors thank the respected reviewer for the comments, the elimination of which certainly allowed us to improve the article, and apologize for the insufficient quality of the manuscript text preparation. We have edited the text, eliminated errors and typos.

Comment 0. There are many trace of AI-generating, such as the abstract and conclusion section.

Response 0. The authors did not use artificial intelligence methods. Moreover, due to an error, the manuscript did not have a "Conclusion" section at all, so we could not generate it.

 Comment 1. The section 2 described the methodology, but not clearly. 

Response 1. We have corrected some designations and terms and hope that now medolology is cleaner

 

2. There isn't section 4.

Response 2. Corrected

 

3. There are many writing errors and grammar errors.

Response 3. The article has been edited by a native speaker.

Also, the figures' resolution aren't high enough to read clearly. When there are two or more subgraph in a figure, a), b) etc. need to be identified in the figure, such as Fig.6.

Response. Corrected, high resolution images have been added.

4.The keywords, unmanned aerial vehicles and UAV have the same meaning. Only one needs be kept. 

Response 4. Corrected.

5.The format of  references is not correct. 2-7 et al, 10-14 et al, and so on. They should be 2-7, 10-14..  [], no reference number in it of line 69; The unit inf Fig.4 should be unified.

Response 5. Corrected.

6.Fig.8 should be Fig.6. The order of figure should be continuous. 

Response 6. Corrected.

7.In order to clearly show the geological background of the study area, the author needs to add a regional geological map and indicate the location information.

Response 7. t is indicated in which area the deposit is located so that one can be sure of the correctness of the geological models. Unfortunately, we cannot indicate the exact coordinates of the survey site in the article, since uranium is a strategic mineral resource in Russia.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript presents a case study of using a semi-airborne transient electromagnetic (TEM) method to investigate the geological structure of a uranium paleovalley. The main goal is to evaluate the performance of a UAV-based semi-airborne TEM system developed by the authors’ team. The authors employed a 1D inversion approach for data interpretation and provided a thorough explanation of the data processing workflow. The inversion results appear to be reliable, especially in light of the available prior geological information, and correspond reasonably well with the interpreted paleovalley profile.

In addition, the authors performed 3D forward modeling to assess the sensitivity of the acquired data. The modeling results suggest that the EM response of a 3D ore body can be detected in the early-time window (before 1 ms), highlighting the lateral extent of 3D targets and exposing limitations of using a purely 1D inversion approach. Furthermore, the authors demonstrate that the current configuration of their UAV-TEM system is not suitable for interpreting targets with induced polarization (IP) effects. These analyses are valuable for advancing UAV-TEM data interpretation and system development, and overall, the manuscript is worthy of publication.

However, several issues should be addressed before acceptance:

1. Lines 37–39: The statement “It is shown that in comparison with earlier versions of the UAV-TEM technology …” is not supported by comparative analysis in the main text. Please avoid overstatements unless such improvements are clearly demonstrated through direct comparison.
2. Table 1 (line ~182): The unit “950B” for output voltage is unclear. What does “B” stand for? Why not express the value in volts (V), which is the standard unit?
3. Line 210: The phrase “this allows to suppress distortions like those shown in Fig. 8” needs clarification. What kind of distortions are present in Fig. 8? Please specify which signal components are distorted and how they are suppressed.
4. Lines 225–226: There is confusion in the formula numbering (e.g., “formula (9) … formula (13)”). Please revise the numbering to ensure clarity and consistency.
5. Line 229: The sentence “r is the difference” is ambiguous. Please clarify what kind of difference is referred to here (e.g., spatial, voltage, field strength, etc.).
6. Formulas (7)–(9): The frequency-domain 1D forward modeling equations could be cited from existing literature instead of being detailed extensively. Consider condensing this part and shifting focus toward the interpretation of inversion results, which is more valuable to readers.
7. Figure 6 Discussion: Please elaborate more on the interpretation of Figure 6. When comparing the inversion results of Profile 3 to the geological section, the uplifted basalt over the paleovalley and the underlying granite bedrock are only clearly resolved on the right side, not the left. Also, the inferred fault is not evident in the inversion section. What could be the reason for these discrepancies? A plausible explanation is needed.
8. Conclusion Section: It is unusual for a manuscript to lack a proper conclusion. The current placeholder (“This section is not mandatory...”) should be replaced with a concise summary of the key findings, methodological insights, and implications of the study.

 

It is also noteworthy that high-quality data were obtained despite the relatively low transmitter current of only 1.5 A, which is quite rare in similar field applications. Additionally, the manuscript should include the measured profile response data so that reviewers can better assess and interpret the potential causes behind certain features observed in the inversion results.

Author Response

We thank the respected reviewer for valuable comments. We tried to eliminate almost all of them.

Comment 1. Lines 37–39: The statement “It is shown that in comparison with earlier versions of the UAV-TEM technology …” is not supported by comparative analysis in the main text. Please avoid overstatements unless such improvements are clearly demonstrated through direct comparison.

 Response 1. This item has been removed.

 

Comment 2. Table 1 (line ~182): The unit “950B” for output voltage is unclear. What does “B” stand for? Why not express the value in volts (V), which is the standard unit?

 Response 2. Corrected.

 Comment 3. Line 210: The phrase “this allows to suppress distortions like those shown in Fig. 8” needs clarification. What kind of distortions are present in Fig. 8? Please specify which signal components are distorted and how they are suppressed.

 Response 3. Corrected. There was a typo - the link should be to Figure 5.

 

Comment 4. Lines 225–226: There is confusion in the formula numbering (e.g., “formula (9) … formula (13)”). Please revise the numbering to ensure clarity and consistency.

 Response 4. Corrected. The numbering of formulas and references to formula numbers in the text have been corrected.

 

Comment 5. Line 229: The sentence “r is the difference” is ambiguous. Please clarify what kind of difference is referred to here (e.g., spatial, voltage, field strength, etc.).

 Response 5. Corrected. Corrected. There was a translation error. Corrected ‘difference’ to ‘radial distance’

 

Comment 6. Formulas (7)–(9): The frequency-domain 1D forward modeling equations could be cited from existing literature instead of being detailed extensively. Consider condensing this part and shifting focus toward the interpretation of inversion results, which is more valuable to readers.

 Response 6. The authors believe that it is better to leave these formulas so that readers less familiar with the issue than the esteemed reviewer do not have to look for them in additional sources and they can get all the information from the text of this article.

Comment 7. Figure 6 Discussion: Please elaborate more on the interpretation of Figure 6. When comparing the inversion results of Profile 3 to the geological section, the uplifted basalt over the paleovalley and the underlying granite bedrock are only clearly resolved on the right side, not the left. Also, the inferred fault is not evident in the inversion section. What could be the reason for these discrepancies? A plausible explanation is needed.

 Response 7. The respected reviewer is absolutely right, the section belonged to a slightly different place on the geological map, which was noticeable in the western part. Now it is brought into better agreement with the a priori data and also began to better correspond to the actual data (the immersion of the basement behind the fault zone was established)

 

Comment 8. Conclusion Section: It is unusual for a manuscript to lack a proper conclusion. The current placeholder (“This section is not mandatory...”) should be replaced with a concise summary of the key findings, methodological insights, and implications of the study.

Response 8. Due to a technical error, the text of the conclusion was not inserted. Corrected.

 It is also noteworthy that high-quality data were obtained despite the relatively low transmitter current of only 1.5 A, which is quite rare in similar field applications. Additionally, the manuscript should include the measured profile response data so that reviewers can better assess and interpret the potential causes behind certain features observed in the inversion results.

Response. In fact, such a current is not unusual for this current source\groundings set and grounding conditions. But we have additionally added another figure with TDEM data by time and its description.

Reviewer 3 Report

Comments and Suggestions for Authors

Review on

Modern Capabilities of the Semi-Airborne UAV-TEM 2 Technology on the Example of Studying the Geological 3 Structure of the Uranium Paleo valley

The manuscript presents the development in the UAV-TEM method in comparison with earlier versions.

It is convincing enough for me; the results are clear and well presented.

My main concerns are mostly structural:

• the Abstract is too long; the technical details should not be involved in it.
• rows 216-254 and 292-311 should be part of the 2^nd
• a summary should be given about the geology of the study site
• there are a lot of typing errors especially spaces and points are not at correct positions.
• Conclusions section must be deleted or filled.

Other issues

• The model applied in numerical modelling is not clear. Was the layered model a two-layer one as in Fig. 2 without the paleo-valley? The paleo-valley itself was taken as in Fig. 2 or its simplified version, a single layer? In that case, in what depth was it and what was its thickness? It should be emphasized that the model is 3D; it is not infinite in Y direction as one could think on basis of Fig. 8., anyway the application of the three profiles would not have any sense.
• row 363 and Fig. 11a.: There is a contradiction between them: The area below 0.001 (not 0.01) mV/A is transparent in the Figure.
• 10 and 11: I think it misleading to present the paleo-valley by a rectangle in Figs. 10 and 11. It would be better only to show its borders at both sides by vertical lines (since it is not possible to present its borders on the Time scale).
• Fig 11.: It should be mentioned that presentation of the relative values is more informative that those of the absolute values (Fig 11.). A short explanation for the artifact at about 0.02ms should be given.
• rows 382-383: Do they belong to which profiles? Where is this anomaly contribution drop seen?
• The quality of the manuscript could be improved presenting the limit of the method by numerical investigations. The same model could be used to illustrate the threshold for paleo-valley’s thickness (in the same depth), or threshold of the depth with the same thickness.
• The limits according to registration of the IP effects is discussed. A more positive conclusion could maybe finish the paper by emphasising the result in the EM induction.

A few details are missing:

What was the flying height of the six-rotor copter? Does it concern?

Its type, weight, size?

What is the weight of the frame and the registrator/ADC ?

 

Have a good work!

Author Response

The authors are grateful to the esteemed Reviewer for his attentive attitude to the article and valuable comments. We tried to either take them into account or to substantiate our position with arguments.

Comment 1. My main concerns are mostly structural:

• the Abstract is too long; the technical details should not be involved in it.
• rows 216-254 and 292-311 should be part of the 2^nd
• a summary should be given about the geology of the study site
• there are a lot of typing errors especially spaces and points are not at correct positions.
• Conclusions section must be deleted or filled.

Response 1. The structure of the work has been changed. The abstract has been slightly shortened. The geological description has been supplemented. Typos have been corrected. The conclusion has been added.

 

Comment 2. The model applied in numerical modelling is not clear. Was the layered model a two-layer one as in Fig. 2 without the paleo-valley? The paleo-valley itself was taken as in Fig. 2 or its simplified version, a single layer? In that case, in what depth was it and what was its thickness? It should be emphasized that the model is 3D; it is not infinite in Y direction as one could think on basis of Fig. 8., anyway the application of the three profiles would not have any sense.

Response 2. The model for numerical modelling was taken from Fig. 2 with all the specified parameters. The object itself is composed of several rectangular parallelepipeds. The dimensions of the objects were added to the PGM section. The depth to the top of the object is up to 100 meters at the edges of the paleodoline and up to 120 meters in the center. The thickness is 40 m.

 

Comment 3. row 363 and Fig. 11a.: There is a contradiction between them: The area below 0.001 (not 0.01) mV/A is transparent in the Figure.

Response 3. Corrected.

 

Comment 4. 10 and 11: I think it misleading to present the paleo-valley by a rectangle in Figs. 10 and 11. It would be better only to show its borders at both sides by vertical lines (since it is not possible to present its borders on the Time scale).

Response 4. Corrected.

 

Comment 5. Fig 11.: It should be mentioned that presentation of the relative values is more informative that those of the absolute values (Fig 11.). A short explanation for the artifact at about 0.02ms should be given.

Response 5. Fig. 9b shows a comparison of the probing curves. It can be seen that at early times <0.03 ms the amplitude of the EMF of curve 2 is smaller than the EMF of curve 1, and after this time, since the field decreases more slowly in a conducting medium, the EMF of curve 2 becomes larger. Hence the small contribution with a negative sign in Fig. 11 (now 12).

 

Comment 6. rows 382-383: Do they belong to which profiles? Where is this anomaly contribution drop seen?

Response 6. The description was misleading. This has been corrected. In the corrected paper, these are now lines 411-419.

 

Comment 7. The quality of the manuscript could be improved presenting the limit of the method by numerical investigations. The same model could be used to illustrate the threshold for paleo-valley’s thickness (in the same depth), or threshold of the depth with the same thickness.

Response 7. If we have understood the remark correctly, then it is recommended to conduct additional modeling to show the situation in case the paleovalley thickness becomes smaller, or if its depth changes. But then it is necessary to model an infinite number of situations - after all, both the object and the host rocks can have different resistances, the current can be different, etc., etc. There is no way to consider all possible geological situations, but it seems to us that the manuscript provides a sufficient number of characteristics and information that allow us to judge the capabilities of this UAV-TEM method in general, including the quality of the sounding curves and the noise of the system.

 

Comment 8. The limits according to registration of the IP effects is discussed. A more positive conclusion could maybe finish the paper by emphasising the result in the EM induction.

Response 8. It seems to us that the conclusion is neither negative nor positive, we are simply absolutely convinced, and we present data for this, that such systems in such geological situations will not be able to register the IP parameter. All electromagnetic prospecting methods have their limitations, and in our opinion there is nothing negative about this.

Comment 8. A few details are missing:

What was the flying height of the six-rotor copter? Does it concern?

Its type, weight, size?

What is the weight of the frame and the registrator/ADC ?

Response 8. The dimensions and weight in the measuring system are given in the paragraph following Figure 3 (4 kg), as same as copter type (hexa).

The survey altitude (40 meters under the sensor) is indicated at the beginning of the Results section.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Well addressed, thank you for your work.