the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 25 Feb 2025
Tectonic controls on the formation and evolution of internally drained systems in the western Betics fold-and-thrust belt (S Spain)
Abstract. We analyse the drainage network in a depressed area within the western Betics fold-and-thrust belt (southern Spain) to investigate the Atlantic-Mediterranean water divide evolution after the Messinian Salinity Crisis (last 5 My). To do that, we made a hydro – geomorphic evaluation of streams and endorheic basins together with a detailed field-based analyses of post-Serravallian structural features. Results from the analysis of stream profiles and the application of SLk and χ indexes showed that Mediterranean streams present a higher incision capacity than Atlantic streams, tributaries of the Guadalquivir river. Moreover, several rivers captures of Atlantic river watersheds and of endorheic basins have been described and quantified. Although the Atlantic-Mediterranean water divide will probably move NW-ward, endorheic basins will still endure, hosted in a depressed area located between two active transpressive zones (the Algonales-Badolatosa and Torcal shear zones). Our results confirm that active tectonics have reshaped the area more intensively than previously considered, and that this modification had significant hydrological implications.
Competing interests: In previous works, we received unfair revisions from: Javier Elez (Universidad de Salamanca) and Pablo G. Silva (Universidad de Salamanca).
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.- Preprint
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RC1: 'Comment on egusphere-2025-538', Anonymous Referee #1, 24 Apr 2025
Jiménez-Bonilla et al proposed a new history of uplift and tectonic process to explain the Atlantic-Mediterranean water divide evolution and migration within the Betics fold and thrust belt since the Messinian time during the Messinian Salinity Crisis to Quaternary time. They applied rigorous geomorphological, geomorphometric and geological methodologies in order to show how the tectonics strongly influenced the evolution and migration of the water divide. They show that uplift and associated erosion processes are strongly controlled by the Messinian-Quaternary tectonic activity occurred in this part of the Betics Chain.
I really liked how they proposed this new view and the link with the tectonic activity. They clearly state in the Introduction which was the scientific gap to fill, and which methodologies would have applied.
I believe that this paper is worth for the publication before some minor comments attached the pdf file.
The only comment I state here is related to the last figure. Authors show a really detailed history of the evolution and migration of the water divide, strongly influenced by the tectonic activity, yet the last figure (Figure 11) shows scarce details about it. I would challenge authors to be more creative with Figure 11 trying to propose a more detailed figure (some 3D cartoon with all 4 phases since Messinian time…), where tectonics is shown more clearly. For example, authors could show where the TSZ zone is within the bigger figure of the Atlantic-Mediterranean palaeogeography. I believe this would help readers to better see all the detailed evolution described in their Results and Discussion. Of course, this is not something that would stop the publication but I believe it could give the last missing bit to this paper.
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AC1: 'Reply on RC1', Alejandro Jiménez-Bonilla, 14 May 2025
The only comment I state here is related to the last figure. Authors show a really detailed history of the evolution and migration of the water divide, strongly influenced by the tectonic activity, yet the last figure (Figure 11) shows scarce details about it. I would challenge authors to be more creative with Figure 11 trying to propose a more detailed figure (some 3D cartoon with all 4 phases since Messinian time…), where tectonics is shown more clearly. For example, authors could show where the TSZ zone is within the bigger figure of the Atlantic-Mediterranean palaeogeography. I believe this would help readers to better see all the detailed evolution described in their Results and Discussion. Of course, this is not something that would stop the publication but I believe it could give the last missing bit to this paper.
Answer and Modification: Thank you very much for your valuable comments. We agree with the reviewer and we improved the figure. We added more information related to structures (adding some normal faults and folds) and to the Messinian Salinity Crisis. We added the effects of the sea level drop in the Mediterranean watershed during the Messinian, which probably lead to the formation of deep gullies. However, it is not possible to make a 3D model because the kinematics of structures is really complex and most of displacements would be out-of-plane.
LINE 18: How can say this. Perhaps it is something to show in the Discussion as possible scenario?
Answer and Modification: Thank you very much for this comment. We have included this hypothesis in the discussion section. Line 663: “). Nevertheless, they could be completely destroyed because of a quick NW-ward water divide movement.”
LINE 82: I would change with… “In this study, we aim to explore… “
Answer and Modification: We totally agree, we changed it accordingly.
LINE 84: I would change with… “we analyse”
Modification: Changed.
LINES 122, 130, 308, 346, 511 and 683 mention small changes in the MS.
Answer and Modifications: We totally agree with these changes and we introduced them in the new MS.
LINE 518: What do you mean with “emersion”? Do you mean emersion from the sea level? Do you mean the onset of the uplift? You should rephrase it.
Answer and Modifications: This sentence is confusing; thus, we improved the sentence and we write: “emersion from the sea level”. Uplift probably started before upper Miocene.
LINE 554: You need to specify units of measurements for strain rate values.
Answer and Modifications: We measured strain rate values in the Mesozoic units that crop out in the TSZ. We included it in the new MS.
LINE 562: Again, you need to explain better this word and the related meaning.
Answer and Modifications: Yes, we included the meaning: emersion from the sea level.
LINE 568: Rephrase it. I don`t understand what you mean.
Answer and Modifications: This sentence is confusing. We included: “from the rest of the Guadalquivir foreland basin”.
Finally, we appreciate this reviewer for the precious time in reviewing the paper and the comments, which help to improve the manuscript.
The authors.
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AC1: 'Reply on RC1', Alejandro Jiménez-Bonilla, 14 May 2025
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RC2: 'Comment on egusphere-2025-538', Anonymous Referee #2, 29 Apr 2025
In this study, the authors investigated the evolution of the Atlantic-Mediterranean water divide in the western Betics (southern Spain) following the Messinian Salinity Crisis, using hydro-geomorphic analysis and structural field data. Their results reveal that active tectonics have strongly reshaped the region, enhancing the incision power of Mediterranean streams, driving river captures, and influencing the persistence of endorheic basins within a tectonically constrained depression.
The study is well-organized, featuring a strong introduction and a comprehensive background section. The results are interesting, though they could be further enriched, and the discussion has room for improvement. Specifically, the role of karst processes in the development of endorheic basins and in the evolution of underground water circulation is not addressed. This omission could significantly influence the interpretation of results, especially in relation to the calculation of the χ index.
In conclusion, if the authors make an effort to address this aspect, the manuscript would be acceptable for publication.
TECHNICAL ISSUES
LINE 16: Capitalize “River” consistently
LINES 35-38: The statement that drainage systems equilibrate over long timescales is debatable. Drainage system can equilibrate in a very short time. See Cook, K., Turowski, J. & Hovius, N. River gorge eradication by downstream sweep erosion. Nature Geosci 7, 682–686 (2014). https://doi.org/10.1038/ngeo2224
LINES 40-41: Azañon et al. (2015) is not present in the reference list. Consider citing broader, more internationally oriented and recent examples - e.g. Moumeni, M., Delchiaro, M., Ballato, P., Della Seta, M., Nozaem, R., Clementucci, R., ... & Egli, M. (2025). Coupling of tectonics, climate, and lithology in orogenic systems: Insights from cosmogenic 10Be erosion rates and river profile inversion modeling in the Talesh Mountains, NW Iranian Plateau. Tectonics, 44(2), e2024TC008652. https://doi.org/10.1029/2024TC008652
LINES 48-52: This is a very interesting point. Consider expanding on the implications of these findings and previous knowledge.
LINE 64: Replace “inception” with “formation” or “initiation.”
LINES 82-90: Reiterate the main comment - consider the role of karst in shaping endorheic basins. See for reference: Pavano, F., Tortorici, G., Romagnoli, G., & Catalano, S. (2022). Age attribution to a karst system using river long profile analysis (Hyblean Plateau, Sicily, Italy). Geomorphology, 400, 108095. https://doi.org/10.1016/j.geomorph.2021.108095
LINE 173: Better say “aimed at estimating uplift”?
LINE 202: Correct “indices”.
LINES 203-204: Better say “we analyzed the plano-altimetric characteristics of selected rivers”?
LINE 211: Correct “knickpoints” without “- “. Check it in the entire manuscript.
LINE 211: Did you distinguish lithological/tectonic controlled knickpoints? If yes, how? If not, why?
LINE 212: Why did you choose to use SL index and not ksn or mchi or slope area? I think a justification is needed here. As a possible helpful reference see the following paper:
Demoulin, A., Mather, A., & Whittaker, A. (2017). Fluvial archives, a valuable record of vertical crustal deformation. Quaternary Science Reviews, 166, 10-37. https://doi.org/10.1016/j.quascirev.2016.11.011LINES 215 and 218: Equations should be formatted. In “hf” should be a subscript. Use parentheses with “ln”.
LINE 216: How is the index normalized? State the equation SLk=...
LINE 220: What do you do with this horizontal distance? Not clear.
LINES 224-225: You already introduced those acronyms.
LINE 225: Correct “Paleo-watershed”.
LINE 228: How is it estimated? Or is it measured?
LINE 234: Any karst role evidence?
LINE 235: What do you mean? A constant climate from when to when? And how can you assume that? Please explain.
LINE 243: Chi is not an index. Indeed, index does not have a physical unit of measure while Chi is in meters. It should be named "metric". Check the entire manuscript.
LINE 249: “b” should be a subscript. Moreover, “l/n” should be “1/n”.
LINE 251: “0” should be a subscript.
LINES 258-259: It is possible to assess the divide migration if same erodibility is assumed as well as the same base level. Here it is very important to justify the eventual effect of karst on the drainage area changes.
LINE 268: I do not like the results' section subdivision (I, II, III, IV). I would prefer a unique Results section in which you can distinguish 3 subsections dedicated to the main results (Structural analysis, Uplift estimates and Geomorphic analyses).
LINE 308: What does the PNOA acronym stand for?
LINE 341: Correct “hm-hectometric-scale”.
LINE 380: Should not be moved to the methods section?
LINES 407-408: “1” should be a subscript.
LINE 446 and LINE 463: Consider changing “source” with “channel-head”.
LINE 455 and LINE 461: Correct “SLk”
LINE 460 and LINE 468: Correct "River”
LINE 511: Choose a more appropriate term instead of “birth”. Maybe “formation”?
LINE 540: Correct “geomorphological” and explain what models you are talking about.
LINES 544-546: Give more details.
LINE 583: Consider changing “inception” with “formation”
FIGURE 1: Correct “Guadalquivir River” and “Guadalhorce River”. Is the tectonic map taken from some sources? If yes, cite them.
FIGURE 2: Explicit the coordinate reference system.
FIGURE 8: What do you mean by "modified"? Is it not a result of this study? Why show a modified figure here instead of new results?
FIGURE 10: I think it would be better to implement also the lithology here so that you can easily distinguish the lithological controlled knickpoints.
Citation: https://doi.org/10.5194/egusphere-2025-538-RC2 -
AC2: 'Reply on RC2', Alejandro Jiménez-Bonilla, 15 May 2025
In this study, the authors investigated the evolution of the Atlantic-Mediterranean water divide in the western Betics (southern Spain) following the Messinian Salinity Crisis, using hydro-geomorphic analysis and structural field data. Their results reveal that active tectonics have strongly reshaped the region, enhancing the incision power of Mediterranean streams, driving river captures, and influencing the persistence of endorheic basins within a tectonically constrained depression.
The study is well-organized, featuring a strong introduction and a comprehensive background section. The results are interesting, though they could be further enriched, and the discussion has room for improvement. Specifically, the role of karst processes in the development of endorheic basins and in the evolution of underground water circulation is not addressed. This omission could significantly influence the interpretation of results, especially in relation to the calculation of the χ index.
Answer and Modifications: We thanks the revferee for the effort to review the MS. We understand that the referee is suggesting that if karstification is responsible for the nucleation of playa-lakes and ponds, it must also influence the drainage network and thus, the results derived from the application of the X metrics. However, our understanding is that classical karstification (at least in limestones) typically creates recharge systems, such as dolines. Those ecosystems are normally fresh-water bodies. However, countryside and playa-lakes in Andalusia tend to function as discharge systems. Although there are different types of playas, most of the systems could be classified as brackish-to-brine discharge water bodies (Rodríguez-Rodríguez, 2007). This distinction highlights a key difference in karstification processes in gypsum. Once the lake has formed, dissolution ceases to be effective, the basin is endorheic, and the bottom of the basin becomes a discharge playa-lake. Therefore, salts accumulate within the lake and below the lake, forming a groundwater brine below the surface of the playa-lake. A saline interphase is created in a similar way as in a coastal aquifer. The most evident case of this situation in Fuente de Piedra Playa-lake, in Málaga province (Kohfahl et al, 2008). Because of that, we discard the classical karstification process as a main process in the study area. To make this issue clearer, we have explained it in the new MS (see subsequent comments).
Kohfahl, C., Rodriguez, M., Fenk, C., Menz, C., Benavente, J., Hubberten, H., ... & Pekdeger, A. (2008). Characterising flow regime and interrelation between surface-water and ground-water in the Fuente de Piedra salt lake basin by means of stable isotopes, hydrogeochemical and hydraulic data. Journal of Hydrology, 351(1-2), 170-187..
Rodríguez-Rodríguez, M. (2007). Hydrogeology of ponds, pools, and playa-lakes of southern Spain. Wetlands, 27(4), 819-830.
TECHNICAL ISSUES
LINE 16: Capitalize “River” consistently
Answer and Modifications: Thank you very much, we homogenized in the ne MS.
LINES 35-38: The statement that drainage systems equilibrate over long timescales is debatable. Drainage system can equilibrate in a very short time. See Cook, K., Turowski, J. & Hovius, N. River gorge eradication by downstream sweep erosion. Nature Geosci 7, 682–686 (2014). https://doi.org/10.1038/ngeo2224
Answer and Modifications: Thank you very much for this comment. We actually mean that the drainage system equilibrate in short periods of time: “ Afterward, drainage networks equilibrium is achieved in relatively short time, from 1000 to 100,000 yr., although the lithology, the climate or the watershed size may change this timespan (Whipple and Tucker, 1999; Korup, 2006).”. In order to make this sentence clearer, we removed “from 1000 to 100,000 yr”, which may be confusing. Moreover, we added this reference.
LINES 40-41: Azañon et al. (2015) is not present in the reference list. Consider citing broader, more internationally oriented and recent examples - e.g. Moumeni, M., Delchiaro, M., Ballato, P., Della Seta, M., Nozaem, R., Clementucci, R., ... & Egli, M. (2025). Coupling of tectonics, climate, and lithology in orogenic systems: Insights from cosmogenic 10Be erosion rates and river profile inversion modeling in the Talesh Mountains, NW Iranian Plateau. Tectonics, 44(2), e2024TC008652. https://doi.org/10.1029/2024TC008652
Answer and Modifications: We totally agree with this comment, we removed Azañón et al. (2015) and we added Moumeni et al., 2025.
LINES 48-52: This is a very interesting point. Consider expanding on the implications of these findings and previous knowledge.
Answer and Modifications: We agree with the reviewer. We explain more in the new MS this issue and we added more references. We added: “These closed watersheds present a rather simple water balance, with inputs mainly from surface runoff and negligible infiltration (e.g. Rodriguez-Rodriguez et al., 2012; Jiménez-Bonilla et al., 2023).”
Jiménez‐Bonilla, A., Díaz‐Azpiroz, M., & Rodríguez, M. R. (2023). Tectonics may affect closed watersheds used to monitor climate change and human activity effects. Terra Nova, 35(1), 58-65.
Jiménez Bonilla, A., Martegani, L., Rodríguez-Rodríguez, M., Gázquez, F., Díaz-Azpíroz, M., Martos, S., ... & Expósito, I. (2024). Late-Quaternary hydrological evolution of Fuente de Piedra playa-lake (southern Iberia) controlled by neotectonics and climate changes. Hydrology and Earth System Sciences Discussions, 2024, 1-27.
LINE 64: Replace “inception” with “formation” or “initiation.”
Answer and Modifications: We changed it into “water divide formation”.
LINES 82-90: Reiterate the main comment - consider the role of karst in shaping endorheic basins. See for reference: Pavano, F., Tortorici, G., Romagnoli, G., & Catalano, S. (2022). Age attribution to a karst system using river long profile analysis (Hyblean Plateau, Sicily, Italy). Geomorphology, 400, 108095. https://doi.org/10.1016/j.geomorph.2021.108095
Answer and Modifications: In our study area, karstic processes are not significant in the endorheic watershed inceptions. Water balances of playa-lakes are actually conditioned by the presence of low-permeability rocks such as clays. In the study area, there are local karstic processes related to some isolated dolostones such as Mollina and Humilladero ranges. Karstic processes are not the dominant processes in the formation of these playa-lakes in the area. To make this point clearer, we have included the possibility of these processes in the introduction and we added it in the discussion.
LINE 173: Better say “aimed at estimating uplift”?
Answer and Modifications: We corrected it.
LINE 202: Correct “indices”.
Answer and Modifications: Thanks. We changed it.
LINES 203-204: Better say “we analyzed the plano-altimetric characteristics of selected rivers”?
Answer and Modifications: It is better. We changed it.
LINE 211: Correct “knickpoints” without “- “. Check it in the entire manuscript.
Answer and Modifications: In order to be consistent, we removed the “-“ in the new MS.
LINE 211: Did you distinguish lithological/tectonic controlled knickpoints? If yes, how? If not, why?
Answer and Modifications: We did not use knickpoints controlled by lithology. We explained better in the new MS by adding: “We discarded knickpoints due to lithological contrast by using the geological maps”
LINE 212: Why did you choose to use SL index and not ksn or mchi or slope area? I think a justification is needed here. As a possible helpful reference see the following paper:
Demoulin, A., Mather, A., & Whittaker, A. (2017). Fluvial archives, a valuable record of vertical crustal deformation. Quaternary Science Reviews, 166, 10-37. https://doi.org/10.1016/j.quascirev.2016.11.011Answer and Modifications: It is truth that it is not well address, thus we included in the new MS: “We used this index because this normalization (Demoulin et al., 2017) allows us to obtain comparable values between different rivers and to compare with other works in the study area (e.g. Jiménez-Bonilla et al., 2015).”
LINES 215 and 218: Equations should be formatted. In “hf” should be a subscript. Use parentheses with “ln”.
Answer and Modifications: We included them in the new MS.
LINE 216: How is the index normalized? State the equation SLk=...
Answer and Modifications: The mathematical development is well explained in Pérez-Peña et al., 2009. We included it in the new MS.
LINE 220: What do you do with this horizontal distance? Not clear.
Answer and Modifications: It was not clear, then we changed this sentence into: “Measurements were made each 250 m along stream profiles”
LINES 224-225: You already introduced those acronyms.
Answer and Modifications: Yes, then we removed the explanation and we used the acronyms.
LINE 225: Correct “Paleo-watershed”.
Answer and Modifications: Thanks, we corrected.
LINE 228: How is it estimated? Or is it measured?
Answer and Modifications: It was estimated, we changed. We estimated because we considered W/AFS constant. We added it in the new MS.
LINE 234: Any karst role evidence?
Answer and Modifications: Karstic processes are not dominant in the area. Although the karstification of small dolostones/evaporites outcrops may condition the nucleation of some playa-lakes as we mentioned before, they do not influence the endorheic watershed configuration. To make it clearer, we added in the new MS: “Karstic processes as local processes may control the location of some playa-lakes (the flooded areas). Once the lake has formed, dissolution ceases to be effective, the basin is endorheic, and the bottom of the basin becomes a discharge playa-lake (e.g. Fuente de Piedra playa-lake; Kohfahl et al., 2008). "
We added also a new reference:
Rodríguez-Rodríguez, M., Martos-Rosillo, S., Pedrera, A., & Benavente-Herrera, J. (2015). Ratosa playa lake in southern Spain. Karst pan or compound sink?. Environmental Monitoring and Assessment, 187, 1-15.
LINE 235: What do you mean? A constant climate from when to when? And how can you assume that? Please explain.
Answer and Modifications: Climate maintained roughly constant during the Holocene, and changes occurred during the Pleistocene would not significantly change the flooded areas as observed in Jiménez-Bonilla et al., 2024. We better explained in the new MS.
LINE 243: Chi is not an index. Indeed, index does not have a physical unit of measure while Chi is in meters. It should be named "metric". Check the entire manuscript.
Answer and Modifications: Thank you very much for the valuable comment. We changed it along all the MS.
LINE 249: “b” should be a subscript. Moreover, “l/n” should be “1/n”.
Answer and Modifications: Thanks, we changed.
LINE 251: “0” should be a subscript.
Modification: Changed
LINES 258-259: It is possible to assess the divide migration if same erodibility is assumed as well as the same base level. Here it is very important to justify the eventual effect of karst on the drainage area changes.
Answer and Modifications: Thank you very much because this issue had to be explained in the MS. Karstic processes may affect the application of X and the divide migration. As we explained before, karstic processes are not dominant in the study area. When water balances are made, groundwater recharge/discharge into the water body may be discarded, then, most of the endorheic watershed is low-permeable. Moreover, clays and other low-permeability rocks crop out in the study area. To make it clearer, we have included in the new MS: “Karstic processes as local processes may control the location of some playa-lakes (the flooded areas). Once the lake has formed, dissolution ceases to be effective, the basin is endorheic, and the bottom of the basin becomes a discharge playa-lake (e.g. Fuente de Piedra playa-lake; Kohfahl et al., 2008).”
LINE 268: I do not like the results' section subdivision (I, II, III, IV). I would prefer a unique Results section in which you can distinguish 3 subsections dedicated to the main results (Structural analysis, Uplift estimates and Geomorphic analyses).
Answer and Modifications: We totally agree with the reviewer, we changed it in the new MS.
LINE 308: What does the PNOA acronym stand for?
Answer and Modifications: It means Plan Nacional de Ortografía Aérea in Spanish. We included it in the new MS.
LINE 341: Correct “hm-hectometric-scale”.
Answer and Modifications: Changed.
LINE 380: Should not be moved to the methods section?
Answer: This is the simplification of the equation because of the results in the study area. Then, we should maintain this part in the results sections.
LINES 407-408: “1” should be a subscript.
Answer and Modifications: Changed.
LINE 446 and LINE 463: Consider changing “source” with “channel-head”.
Answer and Modifications: Changed.
LINE 455 and LINE 461: Correct “SLk”
Answer and Modifications: Corrected.
LINE 460 and LINE 468: Correct "River”
Answer and Modifications: Corrected.
LINE 511: Choose a more appropriate term instead of “birth”. Maybe “formation”?
Answer and Modifications: Formation is a more adequate term, we changed it in the new MS.
LINE 540: Correct “geomorphological” and explain what models you are talking about.
Answer and Modifications: Formation is a more adequate term, we changed it in the new MS.
LINES 544-546: Give more details.
Answer and Modifications: We included sentences to explain better this model: “Previous works measured the post-Tortonian uplift using geomorphical features related to previous sea level. “. “These models do not consider either the post-Tortonian uplift in the Atlantic watershed.”
LINE 583: Consider changing “inception” with “formation”
Answer and Modifications: Thanks. We changed along the new MS.
FIGURE 1: Correct “Guadalquivir River” and “Guadalhorce River”. Is the tectonic map taken from some sources? If yes, cite them.
Answer and Modifications: Thanks. We changed “River” and we included the source: Balanyá et al., 2007 and Crespo-Blanc et al.., 2016.
FIGURE 2: Explicit the coordinate reference system.
Answer and Modifications: They are UTM coordinates. We added them in the figure captions: “Coordinate system: WGS 84, zone 30N.”
FIGURE 8: What do you mean by "modified"? Is it not a result of this study? Why show a modified figure here instead of new results?
Answer and Modifications: Sorry, they are new results, but geological and other information is extracted from other works. To be clearer, we removed “modified from” in the figure captions.
FIGURE 10: I think it would be better to implement also the lithology here so that you can easily distinguish the lithological controlled knickpoints.
Answer and Modifications: Lithologies were already included in the stream profiles. We added colours to make the figure more readable.
Finally, we appreciate this reviewer for the valuable comments to improve the paper, which help to improve the manuscript.
The authors.
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AC2: 'Reply on RC2', Alejandro Jiménez-Bonilla, 15 May 2025
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RC3: 'Comment on egusphere-2025-538', Anonymous Referee #2, 30 Jul 2025
All scientific issues I had raised have been appropriately addressed. The authors have provided the necessary clarifications, and I consider the revisions satisfactory. I have no further scientific concerns and recommend the manuscript for acceptance in its current form.
Citation: https://doi.org/10.5194/egusphere-2025-538-RC3 -
RC4: 'Comment on egusphere-2025-538', Anonymous Referee #3, 05 Sep 2025
General comments
Dear editor, dear authors,
I have reviewed the manuscript titled “Tectonic controls on the formation and evolution of internally drained systems in the western Betics fold-and-thrust belt (S Spain)”. The manuscript contains interesting data and interpretations of the Western Betic Cordillera in Andalucia, southern Spain. In my younger years I lived in Andalucia for half a year and am therefore reasonably familiar with its geology. My main impression after going through the manuscript is that the presented data and interpretations are reasonably solid and the paper is generally logically structured. I do not see any major scientific flaws in the methods and results. On the downside, the focus of the paper is clearly on the large-scale tectonic part. The authors, however, make a weak attempt to link this to the formation of the playa-lakes, thereby making the paper much less focused and disperse in its objectives. The paper could be streamlined a lot by reducing the importance of the playa-lake part and focusing on the much stronger tectonic part. In my opinion, the work can currently be considered of fair scientific quality and can become of good scientific quality once it has been refocused.
Regarding its scientific contribution: it is not entirely clear to me what the main objectives are. The authors place a heavy emphasis on the tectonic structures controlling the area and their deformation rates, but they also present river capture data related to Atlantic and Mediterranean sides, and at the beginning of the Discussion they state that the understanding of the playa lakes is the main objective, after which the authors delve deep into the closure of the various Mediterranean-Atlantic gateways. So, throughout the manuscript, the authors swing from one apparently important objective to another without sufficient focus. Not all these elements are satisfactorily tied together at the end of the paper, and their individual contribution to the overall scientific debate is not always clearly explored, making it difficult to estimate the quality of the manuscript’s scientific contribution. The inclusion of paleolake levels especially, and a weak attempt to explain their Holocene evolution in relation to 20 Ma-present tectonics, makes the paper much less focused and messier than it should be. The playa lakes are basically sag ponds and it is common knowledge among structural geologists that sag ponds form in strike-slip shear zones. So, there is no need to overly complicate things by including a detailed investigation of paleo water levels. Instead, the authors should focus the paper on the tectonic aspects, as the bulk of their data is dealing with this. So, to me the scientific contribution at the moment is fair, and could become good once the connections between the results are better presented.
The paper needs improvements in terms of legibility. Not all methods are equally well explained and especially in the results section, page upon page of detailed, map-based descriptions are presented that are difficult to understand without continuously going back to one or two figures. There are also results that need extra figures in order to be understandable. There is an abundance of abbreviations used for all the geographic locations. It is impossible to remember all these abbreviations without making a list and keeping track of any new ones being introduced. It would be much better to write out the names of the geographic locations instead of abbreviating them. The usage of English is also inconsistent. Some sections are better written than others, seemingly dependent on which co-author has written what. I would strongly urge the authors to have the manuscript checked by a native English speaker. The presentation is therefore, of fair quality and could become of good quality after improvements are made.
Overall, the paper merits being published, after improvements upon the text. Therefore, I recommend a major revision.
Specific comments
Abstract:
In the Results and Discussion there is a heavy focus on tectonic structural data and the calculation of deformation rates. Strangely enough this is not mentioned in the Abstract. Please mention this in the abstract as well.
The authors start the abstract stating that they want “to investigate the Atlantic-Mediterranean water divide evolution after the Messinian Salinity Crisis (last 5 My)”. But they do not explain why, nor what the current state of knowledge is, regarding this process.
It is also not clear why they place such heavy emphasis on the tectonic evolution since 20 Ma, whereas the MSC occurred during the Pliocene.
l.16. Here endorheic basins are mentioned, but it is not clear what their relation to river capture is.
l.16. Further in the text, the endorheic basins are referred to as “playa-lakes”. This is confusing.
l.19-22. Here, for the first-time tectonic control is mentioned. Since tectonics are described in the first paragraph of the Methods and also Results, the abstract should also start with an explanation of the tectonic part.
Introduction:
l.36. here They state that drainage networks may reach equilibrium in 1 to 100 ka. But this contradicts the author´s own Results and Discussion as they use river profile disequilibrium to infer tectonic activity over timescales of 20 Ma.
l.49-52. This is too specific for the Introduction and the placement of a statement related to ecology is also really weird as the Introduction treats tectonic-related themes here. I therefore suggest to delete these phrases.
l.52. Tectonics, but also changes in subterranean water flow and changes in evaporation due to seasonal or climate change.
l.56. What exactly are “internal zones” in the context of tectonics? The authors place them in the same list as fold and thrust belts and foreland basins. Internal zones, however, is not a tectonic designation. Please use another word, such as tectonic basin, syncline, etc.
l.62-61. The existence of playa-lakes in this topographic depression is in my opinion related to tectonics. After having read the Results presented by these authors, I am under the impression that this topographic depression is situated in a strike-slip shear zone and that the playa-lakes are actually tectonic sag ponds due to localised Riedel shears. If the authors agree with these inferences, they could already mention this hypothesis here. It would immediately make the connection between the playa-lakes and the tectonic context a lot more obvious to the reader, thereby improving upon the readability of the paper.
l.63. Here the authors seemingly contradict themselves again. They state that the playa-lakes are short-lived features, yet in the Results/Discussion they talk about playa-lakes that have aged as old as the early Pleistocene. Also, how can you infer long-term tectonics based on such short-lived features?
l.65. Is the Guadalhorce gateway somehow related to “El Chorro”? Please clarify.
l.67-70. The authors do not explain why the gateway closure was related to the MSC, nor do they mention any literature references of who has said this.
l.70. Not only tectonics, but also an arid climate contributed to increased evaporation and lowering of the Mediterranean Sea level.
l.73-75. Here, the authors appear to give the reason why they performed a tectonic structural analysis in the study area. It would be better to place this information at the beginning of the Introduction and also introduce it in the Abstract as a reason for this writing of this paper. This appears to be one of the main reasons for the paper, so it should have a prominent position in the Abstract/Introduction.
l.82. The objective should go in the same order as the Methods/Results, starting with the tectonic bit.
l.89-90. By stating this at the end of the objectives, the authors suggest that this is the most important aim of the paper. At the same time, no mention of this was made in the Abstract, generating confusion to the reader. I hope that my above comments have shown that the objectives are not properly explained and confusing to the reader.
Main geological and geomorphological features of the study area
l.95. Paleomargins is unclear. Paleomargins of which age and of which inherited tectonic context? Break-up of Pangea, or more recent?
l.96. Please indicate the age and depositional setting (shallow marine?) of the Flysch deposits. Explain what “trough” means in this context.
l.97. When where the Betics and back-arc basin formed? Late Miocene?
l.113. When looking at Fig. 1a, the name of the Western Gibraltar Arc goes from Marocco to Andalucia and passes through the Atlantic. To me, this seems to suggest that the part of the Arc in the Atlantic was eroded. If this is the case, this should be mentioned here to avoid further confusion.
Fig. 2. This figure needs the inclusion of a proper geological map with stratigraphic formations and structural features. The authors make the strange decision to show a geological cross section, but not the geological map. Later on in the text, the authors also present new geological and structural mapping. Without the inclusion of a proper geological map in Fig. 2, it is impossible to compare the already existing geological data with this new data.
Fig. 2 indicate names of the two shear zones where the shear zones are located. The names are now on top of the fold and thrust belts.
Fig. 2 Write out “ADA” in full. Not clear what it means.
Fig. 2. Playa-lake is a strange name in the context of the figure. The figure shows mainly tectonic features, whereas playa-lake is a geographic denomination Playa-lakes are often related to hydrological-meteorological conditions. Referencing to my earlier comment, I think these playa-lakes are actually sag ponds related to the shear zone. So, it would be better to call them sag ponds. That makes the connection to their tectonic origin a lot clearer.
l.140-156. This text is impossible to follow with a proper geological map of the study area, including stratigraphic column, that should be incorporated in Fig. 2.
Methodology
l.174. In the Results new mapping and structural data is presented. In the Methodology it should therefore be clearly stated that this was done and how the data was collected. The authors should also state why this was necessary, e.g., because of contradicting findings by other workers, or absence of certain data that is critical to estimate uplift rates. All this information should be given in a separate paragraph 3.1 with a separate heading called “3.1 Field-based collection of structural data” or something similar.
Only then follows a second paragraph called “3.2 Uplift estimates”.
l.175-177. Here the authors state the estimation of uplift rates as one of the main objectives of the paper. In the Abstract and Introduction, however, this is not clearly stated as an important objective. Please make sure that the importance of this objective is clearly stated in all relevant chapters of the paper. I suggest the authors also clearly explain what the relevance is of late Tortonian uplift in relation to the drainage captures, divide migration and the formation of sag ponds.
l.203. Please explain briefly why exactly the drainage networks were analysed? How is this related to the tectonic part of the former paragraph?
l.224. I do not understand how the average flooded surface can be mapped from a DEM.Wouldn´t it be better to use Google Earth satellite images?
l.224. Only here, for the first time it is mentioned that the playa-lakes may be related to tectonics. As I said before, this should be stated much earlier in the Abstract and Introduction. Also, it is commonly known that sag ponds are related to strike-slip tectonics and that they often from (ephemeral) lakes. So why do the authors not state this more clearly? It would make the link with tectonics so much easier to understand to the reader right from the beginning.
l.225. Why is the paleo watershed boundary important? Please explain the relation to tectonics.
l.228. Average run-off. But this should be paleo run-off, right? Because you are measuring paleolake dimensions. So which paleoclimatic data was used?
l.229. Why are paleo water balances important? I still do not understand their relation to tectonics? Please explain.
l.242-244. Please explain why it is important to assess water divide migration in relation to the objectives of the manuscript? See also lines 256-258 where this was not sufficiently explained.
Results
l.275. “Our new structural data”. This is very contradicting, because earlier on the authors stated that they only used existing data. Also, in the Methods no mention is made at all of the collection of new, field-based data. The authors present stereo plots of fault planes in Fig. 5, but in the methods, this is not mentioned once. What kind of data did you collect? These data should be presented first instead of jumping to the tectonic interpretations in l.277 and further down below. Later on, in the Results the authors mention uplifted blocks, faults and folds and slickensides. Here, one or two figures with photos showing these features should be presented first, before jumping to tectonic interpretations.
On the other hand, if there is no new data at all and if this is compilation of existing data, the data sources should be clearly mentioned and this entire paragraph including the figures, should be moved to Chapter 2, where the study area characteristics are described.
l.290 and below. Here the authors clearly state that they collected new data and they show some photos. Again, this is very confusing. See my comment above in relation to l.275. Figure 6 does not nearly show enough of the described tectonic deformation. I would like to see more photo of displaced strata with fault planes and close-ups of slickensides. From photo A I personally cannot deduct a strike-slip movement, nor the presence of a strike-slip fault. Photos C and D are not helpful at all and should be replaced by more useful photos of tectonic structures. In this paragraph tectonic structures are mentioned, so I don´t understand why there should be photos of lake water balances here.
l.312-343. These results should be explained by means of photos. For each tectonic feature you describe, please show a photo. Only referring to Fig. 5 is not helpful at all as it does not sufficiently show what you are describing.
l.346-361. Here the authors describe the features of Fig. 3 as new Results. But this figure and its content was already presented in the Methods chapter as existing data. Therefore, this is highly contradicting. It is one way or another, but not both.
l.424-425. How do you know they are 3000 years old?
l.424-425 Also, the location of the mapped sag ponds was already shown in Fig. 3. Why are these sag ponds presented here again as new data? To me, they do not represent new data.
Fig. 9. This figure apparently shows the same things as Fig. 3. My suggestion would be to delete Fig. 9.
l.443 and below about the SLk index. The authors have analysed long profiles and knickpoints in relation to tectonics. To improve the readability of the paper, it would be better to discuss the SLK results in a separate paragraph directly below paragraph “4.2 Estimates of post-Tortonian differential surface uplift”, as both paragraphs deal with tectonics. Then a paragraph 4.4 about the Chi values and drainage divide migration should be introduced, followed by 4.5 paleo lake level estimates” or something alike.
l.442-504. The authors describe the longitudinal profile characteristics and SLK values in detail for each river. This makes the text a bit tedious to read. It would be much better to give a short summary of the main findings without going in so much detail.
l.442-481. There are studies that used the SLk values to classify fault slip in terms of activity intensity. Perhaps it would be interesting to the authors to do the same? It could provide a better understanding of which faults are most active in their study area. See for instance: https://www.sciencedirect.com/science/article/abs/pii/S0040195121002249
l.482-489. Here, the authors switch from longitudinal profiles to lake levels and from l.490 onwards they switch again to longitudinal profiles. Please make a separate paragraph for the lake level data.
l.482-489. The authors show variations in lake levels based on DEM mapping and age estimates (unclear to me where the age estimates come from). To me, this does not present additional evidence for tectonic movements. Lake level variations may also be related to climate change, earthquakes, or changes in ground water levels related to agriculture, mining or any other human activity. The time span on which these lake levels changed (the authors stated 3000 years, although unsure where this age is based on), is way too short when compared to the 20 Ma time period on which they analysed tectonic activity. For me personally, the presence of mapped sag ponds in a shear zone, together with all the other structural data, is enough evidence for active shearing. So, my suggestion would be to remove all this paleolake level stuff from the paper. It would make the paper a lot easier to understand. In its current state, there are simply too many different results from very different time periods, generating a “messy” paper if I may say so.
Discussion
l.511-513. There are too many concepts cobbled together here and to me, not everything is related. For instance, to me the playa lakes are sag ponds related to the shear zone. Is this directly related to drainage migration? Not really. Is drainage migration related to the calculated differential uplift of the western Betics? Yes.
So, to me, these are two different topics that the authors fail to merge sufficiently into one coherent unit in this manuscript. By removing the paleolake level stuff from the equation, the paper will become much more streamlined.
l.523-525. Here a statement is made about the Mediterranean-Atlantic gateway. This was briefly mentioned in the Introduction and then never touched upon again until now. This statement further decreases the understandability of the paper as it was not mentioned as one of the main objectives. Therefore, any reference to this gateway would be better removed from the paper. It only generates confusion.
l.518-538.This information was already mentioned in Chapter 2. Why is this repeated here? Not only that, but the authors switch from tectonics, to gateway closures to drainage migration to ocean base level lowering in only a few sentences, making the text very unfocused. Please delete these sentences.
l.606-611. Here the authors state that the lakes are from early Pleistocene age, but elsewhere they stated they were 3000 years, and now they state the oldest known playa-lakes are 30 ka… Please be consistent.
l.606-621. This information is all very inconclusive and does, in my opinion, not add anything useful to what we already know. It is enough to know they are sag ponds in a shear zone. So, to improve the readability of the manuscript, my suggestion would be to delete these sentences.
l.622-631 and below. Here the authors make a much better link between water preservation in the sag ponds and tectonic activity. So, to me, this part of the Discussion is ok, but I do suggest to simplify it a bit and not go into detail about the individual lakes 3 and 3B. Just keep it more general.
l.632-635. Not useful. Lines can be deleted.
l.636-656. Same. Please simplify the text to ~5 lines and do not go into so much detail about the individual playa lakes. The strong part of the paper is the large-scale tectonic part and not the playa-lake part.
l.657-669. Please delete. It detracts from the focus of the paper.
Conclusions
Please refocus the conclusions according the improved focus on tectonics of the manuscript.
Technical corrections
Abstract
l.9. “depressed area” is incorrect English. The correct term would be “topographic depression”.
l.32” In this regard” can be removed. Just start the sentence with “Drainage networks…”
l.33 please change to “…by undergoing changes in longitudinal profile shape….”
l.34 “topological reshape”. Please change to “..by changing the shape of…”
l.36 “networks” should be “network”
l.37 please change to “although this depends on the lithology, the climate or the watershed size.”
l.42 please change “governs” to “create”.
l.43. delete “both favouring their inception”.
l.43 “…and control their subsequent evolution”.
l.58. As stated before, please change “depressed area” to “topographic depression”. Please change in all other parts of the text as well.
l.62 headwaters.
l.62. Illogical sentence. There is not logical connection between headwaters of Mediterranean rivers and being ephemeral. Ephemeral lakes are related to seasonal rainfall. Please rephrase.
l.66 change to “Shallow marine sediments were deposited in this area during this time period and are currently uplifted more than 100 m. a.s.l.”
l.78. Please delete “In this regard, it is worth noting that..”
l.84-85. Delete “To do that, we zoom into this time frame to…” and start the phrase with “We analyse in detail…”
l.85. Delete “timing, reshaping and fluvial captures.”
l.86-88. This phrase is badly written. Please delete and rephrase as “We analyse the evolution of fluvial longitudinal profiles by examining tectonogeomorphic indicators such as the normalised stream length gradient index (SLk), the normalised steepness index (Ksn) and the concavity index Chi.” Please also state the original references.
Main geological and geomorphological features of the study area
Figure 1 is difficult to read due to its small size. Please enlarge the figure.
In the legend of Figure 1a, what kind of sediment is Upper Mioc. to Q? Please spell out late Miocene to Quaternary.
In Fig. 1b, please indicate which side of the water divide is Atlantic and which side is Mediterranean.
Legend Fig. 1b and manuscript text in general: be consistent in the use of “endorheic area“or “topographic depression” when referring to this area.
Fig. 1a and 1b. Please make sure that both figures are exactly the same size and oriented in the same directions. This makes going back and forth between both figures a lot easier.
l.102. Not orthophoto but satellite image.
l.106. Betic not Betics.
l.110 “along, and across the Betics,” Two commas.
l.113. Delete “the second-order”
l.114. Fig 1 should be Fig. 1a.
l.118. These kinematics
l.125. ADA. As said before, “depressed area” is incorrect English. I would suggest “Antequera topographic depression” or “Antequera Depression”. Please clarify you name this area after the town of Antequera located in the area.
l.126-127. Sentence is too long. I suggest to delete “located close to the contact with the Alboran domain.”
l.129 are these endorheic basins the playa-lakes, or as I prefer to call them, the sag ponds? It is really confusing to the reader you use different names for the same topographic feature.
l.130. It is surrounded by areas rising over 100 m above this topographical depression. The highest elevational differences between the basin floor and surrounding peaks are found in the NW, SE and SW boundaries (Fig. 2b).
l.132-139. This is good example of the number of abbreviations that are used. It makes the text really hard to follow, unless the reader starts making a list with abbreviations and their meaning almost immediately. I strongly urge the authors the spell out the names without using the abbreviations in the entire manuscript.
l.146. Please explain how “allochthonous” should be interpreted?
l.146. canopy is another word for a collection of tree tops. I have never heard of this term in a geological context. Please check if canopy is really used in a geological context.
l.147. overlie not lie over.
150-151. How is this information relevant to the manuscript? If it is not directly important to the paper, it would be best removed.
l.153. What sedimentary origin do the Pliocene sediments have? Fluvial, alluvial, glacial?
l.155 Lacustrine dark quaternary sediments should be Quaternary, dark-coloured lacustrine sediments
1.556 delete “being often useful to identify paleo playa lakes. Some of these outcrops are larger than 1,000 hm2”.
l.158 delete “near the divide”
l.160 drained by the…
Methodology
l.172-173 these sentences can be deleted.
l.177 upper Miocene, shallow-marine sediments
l.180 simple shear, not simple shearing
l.182. Here for the first time “extrusion” is used. Before, the term “transpression” was used. Please be consistent and only use one term.
l.184. Here extrusion and transpression are used as two separate terms. But in reality, it is the same thing. I would change “extrusion” for “movement” here.
l.188-192. Please describe the units of the parameters. For instance, in which units is coaxcial strain expressed’ Time t is in seconds, days, years…etc?
Figs. 1, 2 and 3: Which DEM did you use?
l.195 post-Serravallian, main tectonic structures
Fig. 3 blue arrows are flow directions of the rivers? Please indicate in the legend.
Fig. 3 I don´t understand why two separatee designations are used for playa-lake and endorheic basin? Playa-lakes are also endorheic basins! Why not use the name “sag pond” for both?
l.200. Why is the Junta de Andalucía, 2016 mentioned here? What exactly did the regional government of Andalucía provide?
l.206-207 have also been added
l.2010-211. The authors should first explain what features (e.g., knickpoints, concavity, etc) of the rivers they are investigating. Only after that, the authors can state “We displayed post-Serravallian structures on stream profiles to investigate the relationship between knick-points and recent structures”.
l.211. Why are knickpoints studied? Is this in the context of tectonics and/or drainage capture? Please explain, so the reader knows why you are doing this?
l.2019. I would avoid using “River head” here. It would be better to say “the most upstream elevation of the longitudinal river profile”, or “the headwaters of the river”
l.219. River elevation at the river mouth.
l.222. This is the first time that the Fuente Piedra playa-lake and the Campillos playa-lake are mentioned. Why are these playa-lakes important and where are they located? Please insert a reference to the figure where their locations can be found.
l.225. From the Junta de Andalucia.
l.232-233. Please cite the bibliographic reference for these precipitation values?
l.230-235. This is a sentence made up of 6 lines. The sentence is too long. Please insert a full stop after “..western Atlantic coast).” And start a new sentence stating “Variations are also related to local factors…”.
l.237. Paleo flooded surface has been mentioned earlier, but is only explained in detail here. It would be better to remove the earlier mentioning of paleo flooded surface to avoid confusion.
l.239. “perched over” is incorrect English. Please frame it differently.
l.240. Can easily be estimated.
l.246. Depends on, not depends to.
l.254. Please mention the values uses for m/n.
Results
l.268. It would be better to number the paragraphs with the Results instead of saying “Results I”, “Results II”, etc. Just state “4.1 Post-Serravallian structures”.
l.268-271. These lines can be deleted.
Fig. 5. Please indicate “C”, “D”, etc. for the stereo plot subfigures.
Fig. 5 legend. Where does T-travertines belong to? Does it need a separate colour code, or is it included in Quaternary paleo soils or Quaternary lake sediments?
Fig. 5. Why are Quaternary paleo soils mentioned? Please explain this a bit better in the main body of the Results text.
Fig. 5. It is unclear to me if this map was taken from one of the IGME geological maps, or if this is a completely new map based on field data of the authors. Please indicate which is the case.
Fig. 5. Why is there a black square border surrounding stereplots 1 to 5, and no black border surrounding plots 6 and 7?
Fig. 5. The Quaternary lake sediments in dark grey are the playa-lakes, endorheic basins or sag ponds the authors referred to earlier? The number of names for the same thing keeps increasing. Please be consistent and use only one designation.
Fig. 5. In the main figure, please indicate where more or less the ADA, ABSZ, wTSZ, TSZ and any other abbreviations you have come up with so far, are located. Based on the current figure, I cannot clearly see where the shear zones are located.
l.281. Riedel shears, not Riedel.
l.324 highly dipping is incorrect English. Please change to “strongly tilted”.
l.331. Quaternary, not quaternary.
l.345. Delete “5. Results II: Estimates of post-Tortonian differential surface uplift” and replace with “ 4.2 Estimates of post-Tortonian differential surface uplift”.
l.348. as follows
l.364-366. This is interpretative and should be saved for the Discussion.
l.367-398 and Table 1. These are Methods and should be moved to the Methods. Only the results (l.398-404 and Fig. 7) of the calculations should be presented in the Results chapter.
Fig. 7 contains the main results of this paragraph, but this figure is not described in detail in this section. It is only passingly mentioned in l.398. Please describe the figure in more detail and give it more importance in the text.
l.400-401. Please explain why a total contraction value of 0.09-0.11 is better?
l.419. Please change to “4.3 Drainage network characteristics” or something similar. The word “Geomorphic” was not used in the Methods so to avoid confusion it would be better to not use it.
Please separate the longitudinal profile analysis and the paleolake levels in two different paragraphs with two individual headers.
l.431. “Playa-lakes are located in Fig. 9 by numbering”. Please change to “The location of the playa lakes is shown in Fig. 9.”
l.505-508 Can be deleted. Does not provide any new or interesting data.
Discussion
- 512 it is important to…
l.521. during the late Tortonian…above sea level.
l.539-544. Another sentence made up of 6 lines. Please separate in two or three full sentences.
Fig. 11. Not a good figure. Please delete.
l.590 Please do not place so much emphasis on the gateway closure. Instead, start the sentence with the tectonic part, then state something about the gateway closure and finish the sentence with the establishment of the drainage divide.
Citation: https://doi.org/10.5194/egusphere-2025-538-RC4
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