Influence of mechanical parameters and overburden pressure on the mechanical evolution of fault propagation folds: insights from 2D finite-element elastic-plastic models applied to the Ayegan anticline, central Alborz

Document Type: Research Paper

Authors

1 Department of Geology, Faculty of Earth Sciences , Shahid Beheshti University, Tehran, Iran

2 Department of Geology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran

3 Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran

4 Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran

Abstract

Fault-related folding, due to the variety of tectonic setting, seismic and economic importance, has always been of interest to geologists. In this study, we investigate the influence of different aspects of the mechanical parameters (Young's modulus, Poisson's ratio, dilation angle, and cohesion) and boundary conditions (overburden pressure) to determine the fault-propagation folding style and its mechanical evolution through the use of a series of 2D finite-element elastic-plastic models so that the use of inelastic relationships allows permanent strains to develop in response to the applied loads. All FE-models with the mechanical parameters reduced to 15%, except for Young’s modulus and overburden pressure, lead to lower half- wavelength and amplitude values concerning the reference model, and as these parameters are changed by 15% and 30% simultaneously to validate the results, the area reduction is dramatically increased. FE-model results show that area changes in fault propagation fold are as a function of mechanical stratigraphy, mechanical parameters, and overburden pressure. Area loss can also lead to a decrease in permeability through intergranular mechanisms. We apply these insights to the Ayegan anticline, central Alborz that generally show well-designed FE-modelling matched overall structural geometry in the kink-style kinematic model.

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Article Title [Persian]

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Articles in Press, Accepted Manuscript
Available Online from 28 July 2020
  • Receive Date: 01 February 2020
  • Revise Date: 04 July 2020
  • Accept Date: 28 July 2020