Effect of basal friction on surface and volumetric strain in models of convergent settings measured by laser scanner

Nilforoushan, F.; Koyi, Hemin; Swantesson, Jan; Talbot, Christopher J.

doi:10.1016/j.jsg.2007.09.013

Cited by 43 publications

(22 citation statements)

References 48 publications

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“…Volumetric tectonic strain has been documented or inferred previously in various contractional systems. Significant horizontal shortening is accommodated by volume strain in sandbox models [e.g., Adam et al, 2005;Nilforoushan et al, 2008;Koyi et al, 2004]. Porosity loss in marine sediments during accretion and tectonic shortening has also been documented and quantified [Bray and Karig, 1986;Morgan et al, 1994].…”

Section: Deformation Processesmentioning

confidence: 99%

Effects of cohesion on the structural and mechanical evolution of fold and thrust belts and contractional wedges: Discrete element simulations

Morgan

2015

JGR Solid Earth

119

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Particle-based numerical simulations of cohesive contractional wedges can yield important perspectives on the formation and evolution of fold and thrust belts, offering particular insights into the mechanical evolution of the systems. Results of several discrete element method simulations are presented here, demonstrating the stress and strain evolution of systems with different initial cohesive strengths. Particle assemblages consolidated under gravity, and bonded to impart cohesion, are pushed from the left at a constant velocity above a weak, unbonded décollement surface. Internal thrusting causes horizontal shortening and vertical thickening, forming wedge geometries. The mean wedge taper is similar for all simulations, consistent with their similar residual and basal sliding friction values. In all examples presented here, both forethrusts and back thrusts occur, but forethrusts accommodate most of the shortening. Fault spacing and offset increase with increasing cohesion. Significant tectonic volume strain also occurs, with the greatest incremental volume strain occurring just outboard of the deformation front. This diffuse shortening serves to strengthen the unfaulted domain in front of the deformed wedge, preconditioning these materials for brittle (dilative) failure. The reach of this volumetric strain and extent of décollement slip increase with cohesive strength, defining the extent of stress transmission. Stress paths for elements tracked through the simulations demonstrate systematic variations in shear stress in response to episodes of both décollement slip and thrust fault activity, providing a direct explanation for stress fluctuations during convergence.

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Section: Deformation Processesmentioning

confidence: 99%

Effects of cohesion on the structural and mechanical evolution of fold and thrust belts and contractional wedges: Discrete element simulations

Morgan

2015

JGR Solid Earth

119

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“…[26] Two major points were raised from previous analogue and numerical studies: i) the taper increases with increasing basal friction, which leads to a narrower wedge [Burbidge and Braun, 2002;Davis et al, 1983;Nilforoushan et al, 2008]; and ii) with increasing basal friction, principal stresses plunge with higher angles toward the wedge toe, which leads to steeper back thrusts and flatter frontward-verging thrusts [Huiqi et al, 1992.;Mulugeta, 1988;Ruh et al, 2012].…”

Section: Influence Of Basal Frictionmentioning

confidence: 99%

High‐resolution 3D numerical modeling of thrust wedges: Influence of décollement strength on transfer zones

Ruh

Gerya

Burg

2013

Geochem Geophys Geosyst

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[1] The mechanics and dynamics of thin-skinned compressible thrust wedges with prescribed offsets in the backstop, i.e., transfer zones, are investigated using a three-dimensional finite difference numerical model with a visco-brittle/plastic rheology. The main questions addressed are as follows: (i) What is the influence of the initial length of the backstop offset and (ii) what is the effect of the frictional strength of the main décollement on the structural evolution of the brittle wedges along such transfer zones? Results show that the shorter the backstop offset, the earlier these two thrust planes connect, forming a curved frontal thrust along the entire width of the model. Younger, in-sequence thrusts are formed parallel to this curved shape. Long backstop offsets produce strongly curved thrust faults around the indenting corner. Simulations with a weak basal friction evolve toward almost linear frontal thrusts orthogonal to the bulk shortening direction. Increased basal drag in models with a strong décollement favors propagation of the backstop offset into a transfer zone up to the frontal thrust. These simulations revealed that surface tapers of the wedge in front of the backstop promontory are larger than what the critical wedge theory predicts, whereas the tapers on the other side of the transfer zone are smaller than analytical values. This difference is amplified with increasing length of the backstop offset and/or strength of the décollement. Modeled surface elevation schemes reproduce well the topographic patterns of natural orogenic systems such as the topographic low along the Minab-Zendan transform/transfer fault between the Zagros and Makran.

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“…Some fold and thrust belts contain single or multiple weak detachments (salt or shale) such as the Zagros, SW Iran [Davis and Engelder, 1985;Talbot and Alavi, 1996;Bahroudi and Koyi, 2003;Sherkati et al, 2006], the Northern Apennines, Italy [Massoli et al, 2006], the southern Canadian Rocky Mountains [Stockmal et al, 2007], and the Jura of the Alps [Davis and Engelder, 1985]. Mechanically weak layers at the basement-cover interface or between stratigraphic levels of fold and thrust belts influence the deformation style and kinematics of an orogenic system [Davis and Engelder, 1985;Koyi, 1988;Cotton and Koyi, 2000;Costa and Vendeville, 2002;Nilforoushan et al, 2008;Nilfouroushan et al, 2012;Ruh et al, 2012]. In addition, pre-existing faults in the upper brittle crust, acting as weak zones in the basement, can be reactivated and change the localization and distribution of deformation in overlying sedimentary rocks.…”

Section: Introductionmentioning

confidence: 99%

Thermal‐mechanical modeling of salt‐based mountain belts with pre‐existing basement faults: Application to the Zagros fold and thrust belt, southwest Iran

et al. 2013

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[1] Two-dimensional thermal-mechanical models of thick-skinned, salt-based fold and thrust belts, such as the Zagros, SW Iran, are used to address: (1) the degree of deformation and decoupling between cover and basement rocks due to the presence of a weak salt detachment, (2) the reactivation potential of pre-existing basement normal faults due to brittle or ductile behavior of the lower crust (as related to cold or hot geothermal gradients), and (3) variations in deformation style and strain distribution. The geometry and kinematics of the orogenic wedge and the activity of pre-existing basement faults are strongly influenced by the geothermal gradient (defined by the Moho temperature, MT) and basement rheology. We infer that the MT plays a major role in how the lower and upper crust transfer deformation toward the foreland. In relatively hot geotherm models (MT = 600°C at 36 km depth), the lowermost basement deforms in a ductile fashion while the uppermost basement underlying the sedimentary cover deforms by folding, thrusting, and displacements along pre-existing basement faults. In these models, cover units above the salt detachment occur within a less deformed, wide plateau in the hinterland. In relatively cold geotherm models (MT = 400°C at 36 km depth), deformation is mainly restricted to basement imbricate thrusts that form within the orogenic hinterland. Detachment folding, thrusting, and gravity gliding occur within cover sediments above uplifted basement blocks. Gravity gliding contributes to a larger amount of shortening in the cover compared to the basement.Citation: Nilfouroushan, F., R. Pysklywec, A. Cruden, and H. Koyi (2013), Thermal-mechanical modeling of salt-based mountain belts with pre-existing basement faults: Application to the Zagros fold and thrust belt, southwest Iran, Tectonics, 32,

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Effect of basal friction on surface and volumetric strain in models of convergent settings measured by laser scanner

Cited by 43 publications

References 48 publications

Effects of cohesion on the structural and mechanical evolution of fold and thrust belts and contractional wedges: Discrete element simulations

Effects of cohesion on the structural and mechanical evolution of fold and thrust belts and contractional wedges: Discrete element simulations

High‐resolution 3D numerical modeling of thrust wedges: Influence of décollement strength on transfer zones

Thermal‐mechanical modeling of salt‐based mountain belts with pre‐existing basement faults: Application to the Zagros fold and thrust belt, southwest Iran

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