Analogue modelling of the inversion of multiple extensional basins in foreland fold-and-thrust belts

Molnar, Nicolás; Buiter, Susanne

doi:10.5194/egusphere-2022-1014

Cited by 3 publications

(4 citation statements)

References 42 publications

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“…Additionally, extensional faults in typical analogue models show higher angles than what is inferred from friction measurements with ring shear testers (Panien et al, 2006). This is in accordance with the results of other studies that show only weak to no reactivation of pre-existing structures in purely frictional sandbox models (Jara et al, 2018;Marques and Nogueira, 2008;Almilibia et al, 2005;Yagupsky et al, 2008;Molnar and Buiter, 2022). Due to their relatively low friction coefficient, glass beads are a certain exception.…”

Section: Reactivation Propertiessupporting

confidence: 89%

“…Typical examples are models with concurrent sedimentation or erosion where material is added or removed during a hold phase (e.g. Bonnet et al, 2007;Graveleau and Dominguez, 2008;Molnar and Buiter, 2022). With the increased use of computer tomography or laser-based topography scanning to screen experiments comes another type of model that must be interrupted at regular intervals.…”

Section: General Impact Of Time Consolidation On Analogue Modelsmentioning

confidence: 99%

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Time-dependent frictional properties of granular materials used in analogue modelling: implications for mimicking fault healing during reactivation and inversion

2023

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Abstract. Analogue models are often used to model long-term geological processes such as mountain building or basin inversion. Most of these models use granular materials such as sand or glass beads to simulate the brittle behaviour of the crust. In granular material, deformation is localised in shear bands, which act as an analogue to natural fault zones and detachments. Shear bands, also known as faults, are permanent anomalies in the granular package and are often reactivated during a test run. This is due to their lower strength compared to the undeformed material. When the fault movement stops, time-dependent healing immediately begins to increase the strength of the fault. Faults that have been inactive for a long time therefore have a higher strength than younger faults. This time-dependent healing, also called time consolidation, can therefore affect the structure of an analogue model as the strength of the fault changes over time. Time consolidation is a well-known mechanism in granular mechanics, but it is poorly described for analogue materials and on the timescales of typical analogue models. In this study, we estimate the healing rate of different analogue materials and evaluate the impact on the reactivation potential of analogue faults. We find that healing rates are generally less than 3 % per 10-fold increase in holding time, which is comparable to natural fault zones. We qualitatively compare the frictional properties of the materials with grain characteristics and find a weak correlation of healing rates with sphericity and friction with an average quality score. Accordingly, in models where there are predefined faults or reactivation is forced by blocks, the stability range of the fault angles that can be reactivated can decrease by up to 7∘ over the duration of 12 h. The stress required to reactivate an existing fault can double in the same time, which can favour the development of new faults. In a basin inversion scenario, normal faults cannot be inverted because of the strong misorientation, so time consolidation plays little additional role for such models.

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Section: Reactivation Propertiessupporting

confidence: 89%

Section: General Impact Of Time Consolidation On Analogue Modelsmentioning

confidence: 99%

Time-dependent frictional properties of granular materials used in analogue modelling: implications for mimicking fault healing during reactivation and inversion

2023

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show abstract

“…Additionally, extensional faults in typical analogue models show higher angles than what is inferred from friction measurements with ring-shear testers (Panien et al, 2006). This is in accordance with the results of other studies that show only weak to no reactivation of preexisting structures in purely frictional sandbox models (Jara et al, 2018;Marques and Nogueira, 2008;Almilibia et al, 2005;Yagupsky et al, 2008;Molnar and Buiter, 2022). Due to their relatively low friction coefficient, glass beads are a certain exception.…”

Section: Reactivation Of Faults In Basin Inversion Modelssupporting

confidence: 89%

Time-dependent Frictional Properties of Granular Materials Used In Analogue Modelling: Implications for mimicking fault healing during reactivation and inversion

Rudolf

Rosenau

Oncken

2022

Preprint

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Abstract. Analogue models are commonly used to model long-term geological processes such as mountain building or basin inversion. The majority of these models use granular materials like sand or glass beads to simulate the brittle behaviour of the crust. In granular materials deformation is localized into shear bands that act as analogues to natural fault zones and detachments. Shear bands aka faults are persistent anomalies in the granular package and are frequently reactivated during an experimental run. This is due to their lower strength in comparison to the undeformed bulk material. When fault motion stops, time dependent healing immediately starts to increase the strength of the fault. Therefore, older faults show a higher strength in comparison to younger faults. This time dependent healing, also called time consolidation, can therefore affect the structural style of an analogue model due to evolution of fault strength over time. Time consolidation is a well known mechanism in granular mechanics but remains poorly characterized for analogue materials and on the timescales of typical analogue models. In this study, we estimate the healing rate of several analogue materials and evaluate the consequences on the reactivation potential of analogue faults. We find that the healing rates are generally below 3 % per tenfold increase in hold time which is comparable to natural fault zones. We qualitatively compare the frictional properties of the materials with grain characteristics and find a weak correlation of healing rates with sphericity and friction with an average quality score. In models where predefined faults exist or reactivation is forced by blocks, the stability region of fault angles that can be reactivated can accordingly decrease by up to 7° over the duration of 12 hours. The stress required to reactivate a preexisting fault can double in the same time which may favor the creation of new faults. In a basin inversion scenario, normal faults can not be inverted due to severe misorientation and therefore time consolidation plays only a minor additional role for such models.

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“…Data availability. Images, videos, and selected raw PIV-exported files are freely available as a data publication deposited in the GFZ Data Services database (https://doi.org/10.5880/fidgeo.2023.011, Molnar and Buiter, 2023).…”

Section: Basin Upliftmentioning

confidence: 99%

Analogue modelling of the inversion of multiple extensional basins in foreland fold-and-thrust belts

Molnar

Buiter

2023

Solid Earth

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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 horizontal stresses can act and reactivate extensional structures due to their intrinsic irregular patterns of deformation deflection and localisation. Overprinting events and relative dating uncertainties in the geological record make it difficult to interpret 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 stage. 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 orogenic front also show evidence of mild inversion at early stages but are characterised only by basin infill contraction and uplift. When multiple extensional basins are present, the degree and type of inversion will depend primarily on their relative location and distance to the orogenic front. Here we also prove that the presence of additional extensional features in the vicinity of a basin can be a first-order controlling factor in their overall 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 provide comparisons with natural examples that shed light on some still unanswered questions related to the process of basin inversion in orogenic belts.

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Analogue modelling of the inversion of multiple extensional basins in foreland fold-and-thrust belts

Cited by 3 publications

References 42 publications

Time-dependent frictional properties of granular materials used in analogue modelling: implications for mimicking fault healing during reactivation and inversion

Time-dependent frictional properties of granular materials used in analogue modelling: implications for mimicking fault healing during reactivation and inversion

Time-dependent Frictional Properties of Granular Materials Used In Analogue Modelling: Implications for mimicking fault healing during reactivation and inversion

Analogue modelling of the inversion of multiple extensional basins in foreland fold-and-thrust belts

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