Propagation of a fold-and-thrust belt over a basement graben

Caër, Typhaine; Souloumiac, Pauline; Maillot, Bertrand; Leturmy, Pascale; Nussbaum, Christophe

doi:10.1016/j.jsg.2018.07.007

Cited by 12 publications

(2 citation statements)

References 23 publications

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“…Despite this extensive heritage, the Jura fold-and-thrust belt is commonly presented as the archetype of a thin-skinned fold-and-thrust belt formed by the activation of the evaporitic Triassic layers as a décollement (Buxtorf , 1916;Laubscher, 1961; Burkhard, 1990;Burkhard and Sommaruga, 1998;Pner, 2006;Madritsch et al, 2008Madritsch et al, , 2010. The inherited faults are considered to have inuenced the thin-skinned deformation by localizing the ramps (Ustaszewski and Schmid, 2007;Caër et al, 2018;Schori et al, 2021;Schori, 2021).…”

Section: Emplacement Of the Jura Fold-and-thrust Beltmentioning

confidence: 99%

Parametric mechanical analysis of thin- versus thick-skinned tectonics applied to the Jura belt

Caër¹,

Maillot²,

Leturmy³

et al. 2023

BSGF - Earth Sci. Bull.

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Field observations and seismic interpretations testify that the front of the Jura fold-and-thrust belt is still submitted to compressive deformation, but whether the basement is deforming (thick-skin) or not (thin-skin) remains an open question. We propose a mechanical point of view using the Kinematic approach of the Limit Analysis theory (KLA). We first draw cross-sections containing a major shallow décollement level in the triassic evaporites, including the Alps up to the topographic maximum and including the whole crust. We submit the cross-sections to a compressive force at their southern end, and the KLA determines the location and geometry of the incipient ruptures by optimisation of the associated compressive force, accounting for mechanical balance and the rock strength (Coulomb criterion). Five cross-sections span the whole Jura from west to East, allowing us to explore the lateral variations. From the analysis of five hundred simulations (one hundred for each cross section), varying the friction angles on the Triassic décollement and of the lower crust between 1 deg and 10 deg, we have identified five types of tectonics at the Jura front depending on the emergence of a basement thrust beyond the Jura front (type 1), at the Jura front (type 2) with simultaneous activation of the shallow décollement (type 3), or south of the Jura front (type 5), with activation of the shallow décollement at the Jura front (type 4). The analysis allows us to draw two conclusions. First, the transitions between the various tectonic styles occur abruptly upon continuous changes in the friction parameters, revealing a threshold behaviour that we interpret as an extension of the concept of wedge criticality in the Critical Coulomb Wedge theory: at criticality, several tectonic types may occur within a narrow, critical, range of parameter values. Second, the critical range evolves sytematically between cross-sections, in such a way that the front of the thick-skinned deformation crosses laterally the Jura belt. The two most western cross-section exhibit only thin skin or no tectonics at the Jura front (types 1, 4 and 5), the central one hosts all five styles, and the two Eastern ones show thick-skin solutions (1, 2, 3), for all values tested. We also show that a thick-skinned tectonic style can be accompanied by a simultaneous activation of the shallow triassic décollement (type 4), complicating the interpretation of apparent thin-skin field structures. Modifications of our cross-sections to explore the effect of a bumpy upper/lower crust interface, or of a major décollement at the upper/lower crust interface show the robustness of our conclusions. They only modify slightly the critical ranges at which the tectonic changes occur. These findings may serve as guides, or first order questions, for more sophisticated mechanical approaches including temperature and rate dependent rheologies and the three dimensions of space.

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Section: Emplacement Of the Jura Fold-and-thrust Beltmentioning

confidence: 99%

Parametric mechanical analysis of thin- versus thick-skinned tectonics applied to the Jura belt

Caër¹,

Maillot²,

Leturmy³

et al. 2023

BSGF - Earth Sci. Bull.

View full text Add to dashboard Cite

show abstract

“…Field-based observations, seismic reflection profiles, balanced and restored crustal-scale sections, as well as analogue and numerical models demonstrated the geometry and kinematics observed in contractional settings such as fold-and-thrust belts are controlled by various factors. These factors have been studied, such as the presence of pre-existing structures [e.g., Nilforoushan et al, 2013, Nabavi et al, 2020, Del Ventisette et al, 2021, Najafi et al, 2021, Shamszadeh et al, 2022a, basement morphology and thrust ramp dip angle [e.g., Maillot and Koyi, 2006, Rosas et al, 2017, Caër et al, 2018, Ghosh et al, 2020, the depositional environment, mechanical stratigraphy (i.e. the mechanical properties, thickness of layers, and interface properties of rock units) [e.g., Cruz et al, 2008, Farzipour-Saein and Koyi, 2014, Pla et al, 2019, Ito and Moore, 2021, the presence of décollements (single and/or multiple) and their initial configurations [e.g., Sherkati et al, 2006, Stockmal et al, 2007, Graveleau et al, 2012, Nilforoushan et al, 2012, Ruh et al, 2012, 2017, Watkins et al, 2014, Ghanadian et al, 2017a,b, Li and Mitra, 2017, Borderie et al, 2018, Derikvand et al, 2018, Heydarzadeh et al, 2020, Gu et al, 2021, Eslamirezaei et al, 2022, Mohammadrezaei et al, 2022, the basal slope and velocity [e.g., Rosas et al, 2017], the basal friction [e.g., Cotton and Koyi, 2000, Costa and Vendeville, 2002, Koyi and Maillot, 2007, the angle of convergence [e.g.,…”

Section: Introductionmentioning

confidence: 99%