Structural control of inherited salt structures during inversion of a domino basement-fault system from an analogue modelling approach
- 1Institut de Recerca Geomodels - UB, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), C/ Martí i Franquès s/n, 08028 Barcelona, Spain
- 2Departament de Dinàmica de la Terra i de l´Oceà, GRC Geodinàmica i Anàlisi de Conca (GGAC), Facultat de Ciències de la Terra, Universitat de Barcelona (UB), C/ Martí i Franquès s/n, 08028 Barcelona, Spain
- 3Australian School of Petroleum and Energy Resources, University of Adelaide, South Australia, 5005 Australia
- 4Earth Sciences Department, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
- 1Institut de Recerca Geomodels - UB, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), C/ Martí i Franquès s/n, 08028 Barcelona, Spain
- 2Departament de Dinàmica de la Terra i de l´Oceà, GRC Geodinàmica i Anàlisi de Conca (GGAC), Facultat de Ciències de la Terra, Universitat de Barcelona (UB), C/ Martí i Franquès s/n, 08028 Barcelona, Spain
- 3Australian School of Petroleum and Energy Resources, University of Adelaide, South Australia, 5005 Australia
- 4Earth Sciences Department, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
Abstract. Inversion of an extensional domino-like basement faults system with a pre-extension decoupling layer is presented as a set of analogue models to understand the role of pre-existing structural features during inversion. The present study expands the experimental program by Ferrer et al. (2022a) in which, models were carried out with different salt and overburden thicknesses to investigate the role played by the salt and by the overburden during extension but also, how extensional structures and salt distribution condition the evolution during inversion. The results show that after total inversion of the models, the resultant structural style of deformation is highly influenced by the inherited extensional configuration and by the thickness of salt which they both condition the degree of coupling/decupling between the pre- and syn-kinematic successions. While models with thick salt can partially or totally preserve the extensional ramp-syncline basin geometry independently of the overburden thickness, models with thin salt result in a total inversion of the ramp-syncline basins with the development of crestal collapse grabens and extensional faults affecting the overburden. Compression triggered the development or reactivation of salt-related structures such as primary weld reactivations (i.e., reopening and/or obliteration), diapir rejuvenation, salt thickening, thrust emplacement, etc. The development of these elements is conditioned by the salt thickness distribution at the end of the extension and therefore, a precise understanding of inherited salt-related structures in needed so to understand the inversion of the basin as well as characterise the structural style.
Oriol Ferrer et al.
Status: final response (author comments only)
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RC1: 'Comment on egusphere-2022-1183', Timothy Schmid, 04 Jan 2023
The manuscript by Ferrer et al. presents a series of analogue experiments that investigate an extensional domino-like basement fault system with a pre-tectonic unit under extension and subsequent inversion phase. The pre-tectonic unit, comprising a salt layer and an overburden (with different thickness ratio), acts as a mechanical discontinuity between basement-fault system and a syn-tectonic unit on top. The work provides a carefully laid out presentation of salt-related deformation structures and, the influence of the layer thickness ratio on the style of basin inversion. Thanks to a well-established workflow the authors present quantitative results that allow for a detailed discussion of the salt layer that conditions coupling between the basement-fault system and the overburden succession during inversion. While the extensional phase of the experiments has been previously described by the same authorship, the detailed investigation of the rift inversion part provides novel and original insights into coupling mechanisms and structural reactivation.
The manuscript appropriately reviews published work on the role of salt layers and their role during rift system inversion and introduces previous analogue modelling studies on basin inversion. The conducted models explore different thickness ratios between salt layer and overburden (i.e., the pre-tectonic unit) and test how this thickness ratio influences the style of extensional structures and their reactivation during subsequent inversion. The modelling results are presented based on central 2D cross-sections at final extensional stages and after the identical amount of shortening. These cross section show in great detail extensional structures and their role in the subsequent inversion, and highlight distinctive styles of basin inversion governed by the salt-overburden thickness ratio. This contribution seems well suited for EGU Solid Earth and the special issue Analogue modelling of basin inversion. The manuscript is original, overall well written and well organised. Illustrations are clear and concise and mostly guide the reader (see minor comments below). I would recommend accepting this manuscript after some minor to moderate revisions.
Please find my comments in the attached pdf file.
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RC2: 'Comment on egusphere-2022-1183', Tim Dooley, 12 Jan 2023
Ferrer et al. present a nice modeling study on inversion of a domino-style rift system with prekinematic layers of "salt" embedded within the this sequence. Model salt thickness is varied, as is the suprasalt overburden thickness, in order to better understand the impact of such a weak layeron deformation styles during extension and inversion. A just-published paper by the same lead author focuses solely on extension of a domino-style system with more variety in terms of number of weak layers etc. The authors do refer to this paper and acknowledge that there is some overlap. I don't believe this overlap is problematic at all. This paper is aimed at inversion, and destined for a special issue on inversion.
I like the models presented in this paper and I do think this study should be published after moderate revisions. I have heavily annotated two attached PDFs and would like the authors to revise the manuscript accordingly. My main concerns as it stands right now are:
1. The Introduction is quite poor and some simple revisions should help better frame the study as well as stating what the research questions are. Doing this would also set up the Discussion to answer the questions posed in the Introduction.
2. In the model description section some of the text concerning teh extensional stages of deformation are either not illustrated in any way and are possibly redundant. A better way to describe the models might be to focus on one in both extension and inversion, and then focus on the differences shown by the other models in the series.
3. The discussion needs work in terms of how it flows and for clarity. Answering questions posed in the Introduction might be teh way forward here. See comments on the manuscript. Some issues with terminology here too. Mixtures of impingement and welding can be a struggle. And then effective weld versus full weld – see comments. There is also a lack of comparison of structural styles seen in these models and those from older studies and lack of citing in this section.
4. The figures are all of good quality and necessary but some addditional information on some of these figures is needed – keys to fault colors, annotations etc.
5. Just a general need to tighten the text for clarity etc. See comments.
I hope these comments help to improve the manuscript.
Oriol Ferrer et al.
Oriol Ferrer et al.
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