the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 12 Oct 2022
Analogue modelling of the inversion of multiple extensional basins in foreland fold-and-thrust belts
Abstract. The presence of pre-existing rheological heterogeneities in the lithosphere plays a significant role during subsequent stages of deformation in essentially every geological process. Extensional basins located in foreland fold-and-thrust belts will alter the spatio-temporal evolution of its associated orogen. It remains unclear how far can horizontal stresses act and reactivate extensional structures, and it is difficult to interpret from the geological record how stresses were transferred across a heterogeneous crust. Here we examine the inversion of extensional basins in foreland fold-and-thrust belts by using three-dimensional analogue experiments that simulate first an extensional stage, followed by a shortening cycle. Our results show how extensional basins proximal to the orogenic front effectively localise deformation in the shape of thrusts and prevent stress transfer beyond their location. Basins that are located at large distances from the indenter also show evidence of mild inversion at early stages, but characterised only by basin infill contraction and uplift. When multiple extensional basins are present, although the degree and type of inversion will depend on their relative location and distance to the orogenic front, here were prove that the presence of additional extensional features in the vicinity of a basin can be a first order controlling factor in their reactivation history. We share additional insights of how a fold-and-thrust belt evolves once the extensional basins have been incorporated by the advancing wedge and we hope that comparisons with natural examples will shed light on some still unanswered questions related to the process of basin inversion in orogenic belts.
-
Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
-
Preprint
(2490 KB)
-
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(2490 KB) - Metadata XML
- BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-1014', Pablo Granado, 22 Nov 2022
Dear Nicolás, dear Susanne,
it has been a pleasure to review your ms entitled "Analogue modelling of the inversion of multiple extensional basins in foreland fold-and-thrust belts". The set up of the modeling and the rationale are sound and interesting. It has great imporance for several projects in the foreland of the Alps for instance, where radioactive material may be store in those kind of grabens in a nearby future.
There are few comments on the edited pdf version of the ms that you will find, and that I encourage to address. In general the ms is well written, but I have ecountered several lines that I may have not been able to properly understand.
I will start with the illustrations. I think the ms will benefit from including a rheological profile attached to the Mohr circles. I failed to understand if the syn-rift in fill is made up exclusively of microbeads, or not.
I also think the ms will benefit from showing the images of the sandbox models, without the differential and cummulative strains on top. These can go aside. It is hard to judge the results of the modelling without the models them selves available. At the end, we, as modellers, would like to see the models, the results.
I also miss the results of the extensional phases, along with their differential and cummulative strains overlapped. This is very important to have the pre-shortening configuration (with its inherited fabric) properly characterised, and to be able to judge the role of inheritace. Same as for figures 8 and 9. These are very nice-looking colored cartoons, but not the real results of the model.
There are two comments that I am concern with:
Line 119. "Both sand and microbeads obey the Mohr-Coulomb criterion, where a time-independent rheological behaviour can be assumed" . I understand you mean a non-strain rate dependent rheology, as stated at the footnote of Table 1. However, this statement has been questioned long ago by two works, those of Lhornamm et al. 2003 and Adam et al. 2005 that propose behaviours that depart from the typically adscribed to coulomb materials. Can you comment on those, and question your basin inversion results based on their works?
Line 200. "With ongoing shortening, the thicker sand pile will require an increase in σ1 to maintain the same shortening
rate (Fig. 3e)". Do you mean differential stress (Sigma 1 minus Sigma 3), rather than shortening rate?Comparison with natural case studies.
Schmid et al. 2008 propose the subduction of the Adriatic lithosphere beneath the European one (change in polarity across the Eastern Alps). I do not personally agree with their interpretation since is conjetural and based on the imaging of geophsycal anomalies that do not fit with overall paleogeographical, surface, and shallow subsurface data and models; maybe you could find other reference that suits better to your modelling. Inverted and transported half-grabens are better outcropping in the French Western Alps. I have provided additional references that could suit better to your work.
Other than this, I think the ms is good for publication after addressing some minor revisions and considerations in the annotated pdf file
Best regards
Pablo Granado
Universitat de Barcelona
-
AC2: 'Reply on RC1', Nicolas Molnar, 05 Jan 2023
Dear Pablo Granado,
Thank you very much for the time taken for reading, commenting, and suggesting changes to our recently submitted manuscript. All the points raised have helped us improve the paper considerably.
Regarding the specific aspects mentioned in your response letter:
Figures/Illustrations
Figures 3 to 10 have been modified to reflect the suggested changes and to clarify aspects that weren’t clear. We agree that showing uninterpreted images of our results makes it a better contribution as a modelling paper. The main difference in the illustrations is that all experiment evolution figures now show the final stage of extension and include a panel with raw side-view photographs. Additional comments made in the annotated pdf file regarding suggestions to figures have been addressed accordingly.
Rheological behaviour (comment on line 119)
The reviewer’s comment in the sense that sand shows upon loading first an elastic response followed by strain hardening until peak failure and then some strain softening is of course correct. This is similar to the behaviour of rocks as described in Jaeger and Cook (1976). The elastic response occurs in the initial loading stage and for low differential stress. Mohr-Coulomb behaviour describes the relation between normal stress and shear stress at peak failure or at dynamic stable strength (when strain softening has occurred). This is described in Lohrmann et al. (JSG, 2003), their Figs 2 and 4 (and other Figs) and Panien et al. (JSG, 2006), their Figs 2 and 3. So in this way one is not at all in contradiction with the other. While this is a topic that is usually debated in depth in rheology-specific papers, we don’t consider we need to revisit our basin inversion results, as our strain-rate independent modelling materials are appropriate for modelling critical compressional wedges (also backed by classic studies such as Vermeer (1990) or Krantz (1991), who have shown that fine sands follow a Coulomb criterion) and therefore the comparisons made in the text with the theory and mechanics of basin inversion (Sections 3.1 and 3.2) are valid.
Comparison with natural case studies
We understand that the interpretation given by Schmid et al. to the subduction in particular may be conjectural and some researchers may not agree with it. Since we are focusing on crustal structures in our study, our aim is to refer to previous studies from the point of view of observed/interpreted crustal structures only as well. We have modified the text accordingly to only include references that are less controversial and removed Schmid et al. to avoid further discussion on a topic that is secondary to our particular study (e.g. geodynamical drivers of the orogenic wedge). Since we consider that the chosen natural examples are good analogies to our experiments, given we focus on the crustal scale, we propose to leave the case studies we originally chose, instead of adding another example, for conciseness.
Additional comments and notes
Responses to the individual comments, including the one in line 200, have been appropriately addressed in the attached annotated pdf file.
Please do not hesitate to reach out to us for further clarification in any of the responses given after your insightful revision.
Best regards,
Nicolás Molnar
-
AC2: 'Reply on RC1', Nicolas Molnar, 05 Jan 2023
-
CC1: 'Comment on egusphere-2022-1014', Frank Zwaan, 02 Dec 2022
Very nice models!
A thing that could perhaps be added in Figs. 5-7 is the end of the extensional stage, without compression. I think it would be good to show the initial structures prior to inversion. And would it be possible in these figures to show these initial rift-related structures a bit more? The background images in these figures do show it, but it's rather faint, and it could be nice to have a clearer idea of how the inversion-related deformation acts with respect to these structures, and not only to the sediments?
In Fig. 8, the color differences between rift-related faults and inversion-related faults is not that clear. Would it be possible to choose somewhat different colors (NB: is blue in fact showing rift-related faults? --> see the reverse fault in Fig. 8c).
Citation: https://doi.org/10.5194/egusphere-2022-1014-CC1 -
AC3: 'Reply on CC1', Nicolas Molnar, 05 Jan 2023
Dear Frank Zwaan,
Thank you very much for the time taken for reading our manuscript and commenting on how to improve our illustrations! An additional pair of eyes is always very welcome.
Following your suggestions, which were in line with the reviewers’ comments, Figures 5-7 have been accordingly modified to show the end of the extensional stage, just prior to compression. Also for Figures 4 to 10, uninterpreted photographs of the experiments have been added for a better judgment of our results. Hopefully the illustrations now depict a clearer image of the inversion-related deformation features.
Finally, Figure 8 has been modified to make it easier to differentiate between rift-related faults and inversion-related faults. Light blue lines with white outline have been chosen to make it colourblind-friendly. For consistency, lines in Figure 10 have also been modified to match color for the same type of features observed in the models throughout the whole paper. I am unsure which reverse fault in Fig. 8c the comment is referring to, but yes, all light blue features are associated with the extensional stage.
Please do not hesitate to reach out to us for further clarification in any of the responses given!
Best regards,
Nicolás Molnar
Citation: https://doi.org/10.5194/egusphere-2022-1014-AC3
-
AC3: 'Reply on CC1', Nicolas Molnar, 05 Jan 2023
-
RC2: 'Comment on egusphere-2022-1014', Daniele Maestrelli, 05 Dec 2022
Dear Editor,
I am attaching here my revision comments for the manuscript by Nicolás Molnar and Susanne Buiter.
It’s been a true pleasure to read this interesting manuscript, which deals with analogue modelling of positive inversion tectonics. The Authors performed an experimental series of analogue models to investigate the effect of pre-existing basins on the nucleation and development of thrust faults associated with a subsequent compressive stage.
By changing the number and position of the 1° stage-related basins, and by filling the basin with a less competent material than the undeformed portion of the models, the Authors focuses on the effect of basin shortening and uplift, thrust localization and reactivation and the variation of the strength associated to the presence of less competent materials in the basins.
The manuscript is very well structured, well written and nicely illustrated by figures.
I particularly appreciated the presence of section 3- “Analytical expectation”, that makes clear which are the intents of the modelling and the expected results. This part is then properly discussed in the discussion section, allowing the reader to easily follow Author’s reasoning.
Despite the comparison with nature remains to the first orders, I believe these models represent a good addition in terms of insight about inversion tectonics, providing general insights that can be helpful for interpreting similar natural settings.
I have no major comments to this manuscript, and I suggest acceptance after minor revisions. I attached an annotated pdf file with a few minor comments.
The only suggestion I would give to the Authors is to illustrate in Fig. 4-7 the extensional stages of the modelling, and not only the compressive ones.
I really hope to see this manuscript published soon.
Daniele Maestrelli
-
AC1: 'Reply on RC2', Nicolas Molnar, 05 Jan 2023
Dear Daniele Maestrelli
Thank you very much for the time taken for reading, commenting, and suggesting changes to our recently submitted manuscript. We are taking everything in consideration, and we can tell it will significantly improve the quality and clarity of our study.
First and foremost, we would like to mention that most figures have been amended to reflect the suggested changes, including images of the final extensional stages. This input adds a lot of value to our figures and to the overall take-home message we are trying to convey.
Responses to the individual comments have been appropriately addressed in the attached annotated pdf file.
Please do not hesitate to reach out to us for further clarification in any of the responses given after your insightful revision.
Best regards,
Nicolás Molnar
-
AC1: 'Reply on RC2', Nicolas Molnar, 05 Jan 2023
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-1014', Pablo Granado, 22 Nov 2022
Dear Nicolás, dear Susanne,
it has been a pleasure to review your ms entitled "Analogue modelling of the inversion of multiple extensional basins in foreland fold-and-thrust belts". The set up of the modeling and the rationale are sound and interesting. It has great imporance for several projects in the foreland of the Alps for instance, where radioactive material may be store in those kind of grabens in a nearby future.
There are few comments on the edited pdf version of the ms that you will find, and that I encourage to address. In general the ms is well written, but I have ecountered several lines that I may have not been able to properly understand.
I will start with the illustrations. I think the ms will benefit from including a rheological profile attached to the Mohr circles. I failed to understand if the syn-rift in fill is made up exclusively of microbeads, or not.
I also think the ms will benefit from showing the images of the sandbox models, without the differential and cummulative strains on top. These can go aside. It is hard to judge the results of the modelling without the models them selves available. At the end, we, as modellers, would like to see the models, the results.
I also miss the results of the extensional phases, along with their differential and cummulative strains overlapped. This is very important to have the pre-shortening configuration (with its inherited fabric) properly characterised, and to be able to judge the role of inheritace. Same as for figures 8 and 9. These are very nice-looking colored cartoons, but not the real results of the model.
There are two comments that I am concern with:
Line 119. "Both sand and microbeads obey the Mohr-Coulomb criterion, where a time-independent rheological behaviour can be assumed" . I understand you mean a non-strain rate dependent rheology, as stated at the footnote of Table 1. However, this statement has been questioned long ago by two works, those of Lhornamm et al. 2003 and Adam et al. 2005 that propose behaviours that depart from the typically adscribed to coulomb materials. Can you comment on those, and question your basin inversion results based on their works?
Line 200. "With ongoing shortening, the thicker sand pile will require an increase in σ1 to maintain the same shortening
rate (Fig. 3e)". Do you mean differential stress (Sigma 1 minus Sigma 3), rather than shortening rate?Comparison with natural case studies.
Schmid et al. 2008 propose the subduction of the Adriatic lithosphere beneath the European one (change in polarity across the Eastern Alps). I do not personally agree with their interpretation since is conjetural and based on the imaging of geophsycal anomalies that do not fit with overall paleogeographical, surface, and shallow subsurface data and models; maybe you could find other reference that suits better to your modelling. Inverted and transported half-grabens are better outcropping in the French Western Alps. I have provided additional references that could suit better to your work.
Other than this, I think the ms is good for publication after addressing some minor revisions and considerations in the annotated pdf file
Best regards
Pablo Granado
Universitat de Barcelona
-
AC2: 'Reply on RC1', Nicolas Molnar, 05 Jan 2023
Dear Pablo Granado,
Thank you very much for the time taken for reading, commenting, and suggesting changes to our recently submitted manuscript. All the points raised have helped us improve the paper considerably.
Regarding the specific aspects mentioned in your response letter:
Figures/Illustrations
Figures 3 to 10 have been modified to reflect the suggested changes and to clarify aspects that weren’t clear. We agree that showing uninterpreted images of our results makes it a better contribution as a modelling paper. The main difference in the illustrations is that all experiment evolution figures now show the final stage of extension and include a panel with raw side-view photographs. Additional comments made in the annotated pdf file regarding suggestions to figures have been addressed accordingly.
Rheological behaviour (comment on line 119)
The reviewer’s comment in the sense that sand shows upon loading first an elastic response followed by strain hardening until peak failure and then some strain softening is of course correct. This is similar to the behaviour of rocks as described in Jaeger and Cook (1976). The elastic response occurs in the initial loading stage and for low differential stress. Mohr-Coulomb behaviour describes the relation between normal stress and shear stress at peak failure or at dynamic stable strength (when strain softening has occurred). This is described in Lohrmann et al. (JSG, 2003), their Figs 2 and 4 (and other Figs) and Panien et al. (JSG, 2006), their Figs 2 and 3. So in this way one is not at all in contradiction with the other. While this is a topic that is usually debated in depth in rheology-specific papers, we don’t consider we need to revisit our basin inversion results, as our strain-rate independent modelling materials are appropriate for modelling critical compressional wedges (also backed by classic studies such as Vermeer (1990) or Krantz (1991), who have shown that fine sands follow a Coulomb criterion) and therefore the comparisons made in the text with the theory and mechanics of basin inversion (Sections 3.1 and 3.2) are valid.
Comparison with natural case studies
We understand that the interpretation given by Schmid et al. to the subduction in particular may be conjectural and some researchers may not agree with it. Since we are focusing on crustal structures in our study, our aim is to refer to previous studies from the point of view of observed/interpreted crustal structures only as well. We have modified the text accordingly to only include references that are less controversial and removed Schmid et al. to avoid further discussion on a topic that is secondary to our particular study (e.g. geodynamical drivers of the orogenic wedge). Since we consider that the chosen natural examples are good analogies to our experiments, given we focus on the crustal scale, we propose to leave the case studies we originally chose, instead of adding another example, for conciseness.
Additional comments and notes
Responses to the individual comments, including the one in line 200, have been appropriately addressed in the attached annotated pdf file.
Please do not hesitate to reach out to us for further clarification in any of the responses given after your insightful revision.
Best regards,
Nicolás Molnar
-
AC2: 'Reply on RC1', Nicolas Molnar, 05 Jan 2023
-
CC1: 'Comment on egusphere-2022-1014', Frank Zwaan, 02 Dec 2022
Very nice models!
A thing that could perhaps be added in Figs. 5-7 is the end of the extensional stage, without compression. I think it would be good to show the initial structures prior to inversion. And would it be possible in these figures to show these initial rift-related structures a bit more? The background images in these figures do show it, but it's rather faint, and it could be nice to have a clearer idea of how the inversion-related deformation acts with respect to these structures, and not only to the sediments?
In Fig. 8, the color differences between rift-related faults and inversion-related faults is not that clear. Would it be possible to choose somewhat different colors (NB: is blue in fact showing rift-related faults? --> see the reverse fault in Fig. 8c).
Citation: https://doi.org/10.5194/egusphere-2022-1014-CC1 -
AC3: 'Reply on CC1', Nicolas Molnar, 05 Jan 2023
Dear Frank Zwaan,
Thank you very much for the time taken for reading our manuscript and commenting on how to improve our illustrations! An additional pair of eyes is always very welcome.
Following your suggestions, which were in line with the reviewers’ comments, Figures 5-7 have been accordingly modified to show the end of the extensional stage, just prior to compression. Also for Figures 4 to 10, uninterpreted photographs of the experiments have been added for a better judgment of our results. Hopefully the illustrations now depict a clearer image of the inversion-related deformation features.
Finally, Figure 8 has been modified to make it easier to differentiate between rift-related faults and inversion-related faults. Light blue lines with white outline have been chosen to make it colourblind-friendly. For consistency, lines in Figure 10 have also been modified to match color for the same type of features observed in the models throughout the whole paper. I am unsure which reverse fault in Fig. 8c the comment is referring to, but yes, all light blue features are associated with the extensional stage.
Please do not hesitate to reach out to us for further clarification in any of the responses given!
Best regards,
Nicolás Molnar
Citation: https://doi.org/10.5194/egusphere-2022-1014-AC3
-
AC3: 'Reply on CC1', Nicolas Molnar, 05 Jan 2023
-
RC2: 'Comment on egusphere-2022-1014', Daniele Maestrelli, 05 Dec 2022
Dear Editor,
I am attaching here my revision comments for the manuscript by Nicolás Molnar and Susanne Buiter.
It’s been a true pleasure to read this interesting manuscript, which deals with analogue modelling of positive inversion tectonics. The Authors performed an experimental series of analogue models to investigate the effect of pre-existing basins on the nucleation and development of thrust faults associated with a subsequent compressive stage.
By changing the number and position of the 1° stage-related basins, and by filling the basin with a less competent material than the undeformed portion of the models, the Authors focuses on the effect of basin shortening and uplift, thrust localization and reactivation and the variation of the strength associated to the presence of less competent materials in the basins.
The manuscript is very well structured, well written and nicely illustrated by figures.
I particularly appreciated the presence of section 3- “Analytical expectation”, that makes clear which are the intents of the modelling and the expected results. This part is then properly discussed in the discussion section, allowing the reader to easily follow Author’s reasoning.
Despite the comparison with nature remains to the first orders, I believe these models represent a good addition in terms of insight about inversion tectonics, providing general insights that can be helpful for interpreting similar natural settings.
I have no major comments to this manuscript, and I suggest acceptance after minor revisions. I attached an annotated pdf file with a few minor comments.
The only suggestion I would give to the Authors is to illustrate in Fig. 4-7 the extensional stages of the modelling, and not only the compressive ones.
I really hope to see this manuscript published soon.
Daniele Maestrelli
-
AC1: 'Reply on RC2', Nicolas Molnar, 05 Jan 2023
Dear Daniele Maestrelli
Thank you very much for the time taken for reading, commenting, and suggesting changes to our recently submitted manuscript. We are taking everything in consideration, and we can tell it will significantly improve the quality and clarity of our study.
First and foremost, we would like to mention that most figures have been amended to reflect the suggested changes, including images of the final extensional stages. This input adds a lot of value to our figures and to the overall take-home message we are trying to convey.
Responses to the individual comments have been appropriately addressed in the attached annotated pdf file.
Please do not hesitate to reach out to us for further clarification in any of the responses given after your insightful revision.
Best regards,
Nicolás Molnar
-
AC1: 'Reply on RC2', Nicolas Molnar, 05 Jan 2023
Peer review completion
Journal article(s) based on this preprint
Viewed
| HTML | XML | Total | BibTeX | EndNote | |
|---|---|---|---|---|---|
| 340 | 158 | 21 | 519 | 5 | 4 |
- HTML: 340
- PDF: 158
- XML: 21
- Total: 519
- BibTeX: 5
- EndNote: 4
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
Nicolás Molnar
Susanne Buiter
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(2490 KB) - Metadata XML