Impact of an interbedded viscous décollement on the structural and kinematic coupling in fold-and-thrust belts: Insights from analogue modeling

Borderie, Sandra; Graveleau, Fabien; Witt, César; Vendeville, Bruno C.

doi:10.1016/j.tecto.2017.10.019

Cited by 50 publications

(24 citation statements)

References 88 publications

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“…The variability of the different parameters, in particular the viscosity range of the natural case, introduces a significant uncertainty in the calculation of the shortening velocity of the models, which varies from 0.6 × 10 −6 to 1.7 × 10 −3 m s −1 , that is, 0.2 to 612 cm h −1 . However, as we had to ensure that the silicone employed in our analog models behaves as a Newtonian material, we restricted the shortening velocity to 0.7-0.9 cm h −1 (Luján et al, 2006b;Borderie et al, 2018). With these values of shortening velocity, we calculated the strain rate of our analog models as ε = v M /w, where w is the width of the deformable zone measured in the apex parallel to the shortening direction (between 51 and 65 cm).…”

Section: Scalingmentioning

confidence: 99%

“…Finally, it must be stressed that in our models, the buoyancy of the ductile layer is higher than in the natural cases (Table 1), which should have some influence on the experiment dynamics. Nevertheless, this behavior is assumed in most of the analog modeling set for the simulation of deformation in upper crustal levels (see models of Ferrer et al, 2016;Li and Mitra, 2017;Borderie et al, 2018;Roma et al, 2018 who used the same analog materials as in this paper). Moreover, at the beginning of our experiments, the lateral flow of the silicone was limited, as it was confined by sand.…”

Section: Initial Sand-silicone Packmentioning

confidence: 99%

See 1 more Smart Citation

Analog Models of Fold-and-Thrust Wedges in Progressive Arcs: A Comparison With the Gibraltar Arc External Wedge

et al. 2020

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Section: Scalingmentioning

confidence: 99%

Section: Initial Sand-silicone Packmentioning

confidence: 99%

Analog Models of Fold-and-Thrust Wedges in Progressive Arcs: A Comparison With the Gibraltar Arc External Wedge

et al. 2020

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“…In general, disharmonic structures develop, with the degree of decoupling of the two levels depending on several factors. The most common are the strain rate, the viscosity and thickness of each décollement, and the thickness of the overburden above each décollement (Borderie et al, 2018;Couzens-Schultz et al, 2003;Gestain et al, 2004;Hudec & Jackson, 2011;Sherkati et al, 2006), being the last factor different in each model of our experimental program.…”

Section: Suprasalt/subsalt Structural Relationshipsmentioning

confidence: 99%

Influence of Syntectonic Sedimentation and Décollement Rheology on the Geometry and Evolution of Orogenic Wedges: Analog Modeling of the Kuqa Fold‐and‐Thrust Belt (NW China)

et al. 2019

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Contractional deformation in the outer parts of fold‐and‐thrust belts is in part controlled by the presence of syntectonic sediments and multiple décollements (e.g., the Apennines, the Appalachians, the Pyrenees, the Zagros, or the Sub‐Andean and Kuqa fold‐and‐thrust belts). To better understand the influence of these parameters in the kinematic evolution of fold‐and‐thrust systems, we carried out an experimental study including four 3‐D sandbox models inspired by one of the previously mentioned prototypes, the Kuqa fold‐and‐thrust belt. This belt contains two décollements: a weak synorogenic salt layer and a deeper, preorogenic, and frictionless décollement (i.e., organic‐rich shales) showing along strike variations of rheology. The experimental results show that increasing synkinematic sedimentation rate (i) generates a progressive change from distributed to localized deformation and (ii) delays the development of frontal contractional structures detached on the salt, favoring the formation and reactivation of more hinterland thrusts and backthrusts. With respect to the rheology, our study reveals that as the viscosity of the prekinematic décollement increases, (i) the deformation propagates more slowly toward the foreland, and (ii) the underlying thrust stack becomes broader and lower and has a gentler thrust taper angle. The rheology of the prekinematic décollement defines the distribution and geometry of the structures detached on it that in turn influence the development of overlying, salt‐detached structures. Subsalt structures can (i) determine the areal extent of the salt and therefore of any fold‐and‐thrust system detached on it and (ii) hamper or even prevent the progressive foreland propagation of deformation above the salt.

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“…This, in turns allows for the vertical stacking of basement thrusts behind the hinterland salt pinch out. In another article (Borderie et al, 2018), we illustrate what would be the further evolution of such a system, a system where deformation in the hinterland progresses much longer, then all new basal thrusts are shorter and stack vertically one above the other, leading to a geometry similar to that of an asymmetric anticlinal stack. Simple mechanical considerations can help explain this change in behavior.…”

Section: Discussion / Conclusionmentioning

confidence: 99%

How the presence of a salt décollement in the sedimentary cover influences the behavior of subsalt thrusts in fold-and-thrust belts

Vendeville

Tang

Graveleau

et al. 2017

Bull. Soc. géol. Fr.

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-We conducted a series of analogue experiments on shortening of a brittle cover (dry sand) above a deep, thin, frictional detachment (glass microbeads). In some experiments, the cover was homogeneous, entirely brittle. In others, there was a thin viscous silicone layer (representing salt) embedded at mid height into the cover, and initially located in the foreland of the fold-and-thrust belt. Our goal was to determine whether or not the presence of such a décollement in the cover could have an impact on the mechanics and kinematics of the underlying subsalt thrusts. Results confirm that, once the front of the foldbelt reached the hinterland salt pinch out, the kinematics of the deeper belt changed drastically: its front stopped propagating forward, and most of the subsequent shortening was accommodated by a larger-than-normal slip along the foremost and youngest deep thrust, while, above the salt décollement, the deformation front propagated very fast, creating a very low surface slope. We hypothesize that it is the gentle sub-critical surface slope associated with rocksalt's low viscosity that prevents the build-up of an overall surface slope steep enough to allow the underlying, deep foldbelt to continue propagating forward. Finally, one experiment in which only one half of the width of the model comprised an interbedded viscous décollement has shown that the kinematics of the deep thrust was affected even in the adjacent salt-free domain.Keywords: salt tectonics / fold-and-thrust belts / analogue modeling / décollement Résumé -Influence de la présence d'un niveau de décollement évaporitique situé au sein de la couverture sur l'évolution des chevauchements sub-salifères profonds lors de la propagation d'une chaîne d'avant-pays. Nous avons réalisé une série d'expériences de modélisation analogique étudiant le raccourcissement d'une couverture sédimentaire constituée de matériel fragile (sable sec) enracinée sur un niveau profond frictionnel (microbilles de verre), mais comprenant localement une couche visqueuse interstratifiée de plus faible résistance mécanique (polymère de silicone). Le but de ces expériences était d'analyser l'impact d'un tel niveau de décollement visqueux superficiel sur la mécanique et la cinématique des chevauchements de la zone profonde, et notamment sur les modalités de la transmission de la déformation entre les deux niveaux de décollement. Les résultats expérimentaux confirment bien que, lorsque le front de déformation profond atteint la région où se trouve la série visqueuse interstratifiée, la cinématique des chevauchements profonds change de façon drastique. Le front de déformation profond cesse de se propager vers l'extérieur du modèle, et le chevauchement profond le plus jeune se connecte avec le niveau de décollement superficiel. Ainsi, la plus grande partie du raccourcissement est transmise aux séries superficielles de la couverture. Le front de déformation migre rapidement vers l'extérieur en se propageant sur le niveau à faible résistance mécanique. La pente topograp...

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Impact of an interbedded viscous décollement on the structural and kinematic coupling in fold-and-thrust belts: Insights from analogue modeling

Cited by 50 publications

References 88 publications

Analog Models of Fold-and-Thrust Wedges in Progressive Arcs: A Comparison With the Gibraltar Arc External Wedge

Analog Models of Fold-and-Thrust Wedges in Progressive Arcs: A Comparison With the Gibraltar Arc External Wedge

Influence of Syntectonic Sedimentation and Décollement Rheology on the Geometry and Evolution of Orogenic Wedges: Analog Modeling of the Kuqa Fold‐and‐Thrust Belt (NW China)

How the presence of a salt décollement in the sedimentary cover influences the behavior of subsalt thrusts in fold-and-thrust belts

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