Preprints
https://doi.org/10.5194/egusphere-2024-3134
https://doi.org/10.5194/egusphere-2024-3134
04 Nov 2024
 | 04 Nov 2024
Status: this preprint is open for discussion.

Numerical Investigation of Parameters Influencing Back-Thrust Development in Outer Wedge Fronts of Fold-and-Thrust-Belt Systems

Saeed Mahmoodpour, Florian Duschl, and Michael C. Drews

Abstract. Thrusting in fold-and-thrust belts can manifest in different styles. Here we investigate the parameters influencing back-thrust development over fore-thrust development at the frontal of fold-and-thrust belts using numerical geomechanical forward modelling. We vary the strength of the material involved, dip and friction of the décollement and displacing boundary conditions to examine the impact of these properties on the back-thrust development. The results of this numerical sensitivity analysis reveal that back-thrusting mainly increases with increasing material strength and decreasing friction coefficient of the décollement. Décollement dip has a less prominent impact on back-thrusting, but decreasing the décollement ‘s dip angle enhances back-thrusting likelihood. In summary, we find that the contrast between the work necessary to shear the wedge material and the work necessary to slide along the décollement is the main driver for initiating back-thrusting (high contrast) over fore-thrusting (low or even negative contrast), which compares well with field observations. In addition, we also investigate and discuss the effect of a pure lateral displacement rate boundary condition vs. a coupled lateral and along-décollement displacement rate boundary condition on numerical simulations of back-thrusting development.

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Saeed Mahmoodpour, Florian Duschl, and Michael C. Drews

Status: open (until 22 Dec 2024)

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Saeed Mahmoodpour, Florian Duschl, and Michael C. Drews
Saeed Mahmoodpour, Florian Duschl, and Michael C. Drews

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Short summary
In some situations where the crust plates collide to each other, they deform by creating folds and thrusts. Based on thrusts development direction, they are categorized into fore- or back-thrusts. We use numerical simulation to investigate their development over geological time-scales. We examine the importance of rock strength, friction, displacement type and geometry on back-thrusting with regard to the final geometry of the deformation, as well as the distribution of porosity and stresses.